Dimethylene Spacers in Functionalized Polystyrenes - ACS

Chapter 2

Chemical Reactions on Polymers Downloaded from pubs.acs.org by NANYANG TECHNOLOGICAL UNIV on 09/20/17. For personal use only.

Dimethylene Spacers in Functionalized Polystyrenes 1

Graham D. Darling and Jean M . J. Fréchet

2

Department of Chemistry, University of Ottowa, Ottowa, Ontario K1N 9B4, Canada

Modes of attachment of functional groups to crosslinked polystyrene are discussed (1). Attention is drawn to improved stability and activity of polymer-bound reagents and catalysts incorporating dimethylene spacer between polystyrene aryl and functional group heteroatom, and the simplicity and versatility of their synthesis through high-conversion functional group modifications. B e g i n n i n g as ion-exchange r e s i n s (2), and blossoming as s u p p o r t s f o r s o l i d - p h a s e p e p t i d e s y n t h e s i s (3), f u n c t i o n a l i z e d p o l y s t y r e n e s have p r o g r e s s i v e l y expanded i n v a r i e t y and importance as i n s o l u b l e c a t a l y s t s o r r e a g e n t s i n the s e g r e g a t i o n , s e p a r a t i o n , p r o t e c t i o n , a c y l a t i o n , a l k y l a t i o n , dehydrohalogenation, o x i d a t i o n or reduction of s m a l l m o l e c u l e s , r e a c t i o n s which are o f t e n f o l l o w e d by s i m p l e p u r i f i c a t i o n and r e g e n e r a t i o n of the s o l i d phase (4-, j ) ) . C u r r e n t l y , most of t h e s e r e a c t i v e polymers are prepared from ( c h l o r o m e t h y l ) p o l y s t y r e n e , which i t s e l f i s e a s i l y made by c o n t r o l l e d f u n c t i o n a l i z a t i o n (_2, 6·) o f c o m m e r c i a l l y a v a i l a b l e s t y r e n e - d i v i n y l b e n z e n e copolymer. F a c i l e n u c l e o p h i l i c displacement of l a b i l e b e n z y l i c c h l o r i d e , f r e q u e n t l y under p h a s e - t r a n s f e r c o n d i t i o n s (_7), a l l o w s f u n c t i o n a l f r e e m o l e c u l e s b e a r i n g n u c l e o p h i l i c heteroatoms t o become a t t a c h e d t o the macromolecular m a t r i x . However, the new carbon-heteratom bonds formed i n t h e s e f u n c t i o n a l group m o d i f i c a t i o n s are themselves r e l a t i v e l y f r a g i l e , s i n c e resonance s t a b i l i z e s the p a r t i a l charges devel o p e d d u r i n g t h e i r r u p t u r e ( 8 , 9) as shown below. —(-CH -CH-}~ 2

^CH

2

~*X

1

Current address: IBM

2

Current address: Department of Chemistry, Cornell University, Ithaca, N Y 14853-1301

Almaden Research Laboratory, San Jose, C A 95114

0097-6156/88/0364-0024$06.00/0 © 1988 American Chemical Society


2.

DARLING A N D FRÉCHET

Dimethylene Spacers

25

Many examples o f such b e n z y l i c i n s t a b i l i t y are p r o v i d e d by c l a s s i c a l ( f r e e - m o l e c u l e ) o r g a n i c c h e m i s t r y , as w e l l as a few by t h e s m a l l e r and more s p e c i a l i z e d f i e l d o f polymer-supported r e a g e n t s and c a t a lysts. Hence: - B e n z y l i c q u a t e r n a r y phosphonium and ammonium s a l t s are d e a l k y l a t e d by m i l d h e a t i n g and/or n u c l e o p h i l i c a n i o n s , p a r t i c u l a r l y i o d i d e (9) and t h i o l a t e ( 1 0 ) , but a l s o h y d r o x i d e ( 1 1 ) . Most N - b e n z y l p y r i d i n i u m o r q u a t e r n a r y a r y l ammonium compounds are p a r t i c u l a r l y s u s c e p t i b l e ( 1 2 ) . Decompositions o f t h i s s o r t have s e r i o u s l y l i m i t e d the u s e f u l n e s s o f s o l i d p h a s e - t r a n s f e r c a t a l y s t s d e r i v e d from ( c h l o r o m e t h y l ) p o l y s t y r e n e (13, 1 4 ) . - B e n z y l groups are c l e a v e d from amines heated w i t h i n o r g a n i c a c i d s ( 1 5 ) , c a r b o x y l i c a n h y d r i d e s (16) o r cyanogen bromide ( 1 7 ) . A c i d s a l s o c a t a l y z e the d i s p r o p o r t i o n a t i o n o f benzylamine t o d i b e n z y l a m i n e and ammonia ( 1 8 ) . - N - b e n z y l - s u l f o n a m i d e s are c l e a v e d under " r e l a t i v e l y m i l d c o n d i t i o n s " w i t h potassium a l k o x i d e ( 1 9 ) . - B e n z y l e t h e r s are amongst t h e e a s i e s t t o c l e a v e by Lewis a c i d s ( 2 0 ) . S i g n i f i c a n t c l i p p i n g of such bonds, w i t h consequent l o s s of f u n c t i o n a l i t y , r e s u l t e d d u r i n g attempted H C l - c a t a l y z e d h y d r o l y s e s o f p o l y s t y r e n e - s u p p o r t e d o x a z o l i n e i n t e r m e d i a t e s ( 2 1 , 22) and c h i r a l s u p p o r t s (23, 2 4 ) . - Benzyl-type esters hydrolyze r e l a t i v e l y e a s i l y . This i s w e l l known f o r p o l y m e r i c systems (22, 25, 2 6 ) . - A c e t y l bromide c l e a v e s d i b e n z y l s u l f i d e , w h i l e d i e t h y l o r d i i s o propyl are r e s i s t a n t (27). - B e n z y l - s i l a n e s are n o t immune t o h y d r o x i d e o r o t h e r n u c l e o p h i l e s (28, 2 9 ) . - B e n z y l - n i t r o g e n , s u l f u r , o r -oxygen bonds are somewhat suscept i b l e t o h y d r o g e n o l y s i s , e i t h e r d u r i n g c a t a l y t i c hydrogénation (30, 3 1 ) , o r upon treatment w i t h L - s e l e c t r i d e ( 3 2 ) , o r even l i t h i u m a l u m i nium h y d r i d e ( 3 3 ) . Thus, the chemist or c h e m i c a l engineer may l e g i t i m a t e l y f e a r f u r t h e r a t t a c k by u n d e s i r e d n u c l e o p h i l e s on b e n z y l i c carbon, as a main o r s i d e - r e a c t i o n i n the course of assembly, a p p l i c a t i o n o r r e g e n e r a t i o n o f many members of t h i s s t r u c t u r a l c l a s s o f f u n c t i o n a l polymer, l e a d i n g t o l o s s o f r e a c t i v e s i t e s o r mobile groups from t h e s o l i d phase. As t h e l a s t s t e p o f a s o l i d - p h a s e s y n t h e s i s , such as t h a t o f p o l y p e p t i d e s by M e r r i f i e l d , c o n t r o l l e d s e p a r a t i o n o f pendant from p o l y s t y r e n e support may even be u s e f u l (_3, 25) — b u t g e n e r a l l y such d e c o m p o s i t i o n o f a r e a c t i v e polymer o n l y s e r v e s t o d e a c t i v a t e i t w h i l e i n t r o d u c i n g contaminants t o both s o l i d and l i q u i d phases. I n a d d i t i o n , o x i d a t i o n (15, 34) or a l k y l a t i o n (35, 36) may take p l a c e a t b e n z y l i c methylene carbons made p a r t i c u l a r l y a c i d i c by b e i n g bound a t once t o a r y l and e l e c t r o n - w i t h d r a w i n g groups or p o l a r i z a b l e secondrow elements. D i r e c t c o n n e c t i o n of pendant heteroatom t o p o l y s t y r e n e a r y l i s a s y n t h e t i c a l l y more d i f f i c u l t , but o f t e n s t i l l f e a s i b l e ( 3 7 ) , a l t e r n a t i v e . However, though bonds from phenyl t o many common heteroatoms are r e l a t i v e l y s t r o n g , resonance s t a b i l i z a t i o n o f p a r t i a l p o s i t i v e charge developed on an a r y l a t e d atom a c t i v a t e s i t t o l e a v e o t h e r s u b s t i t u e n t s : a l k y l a n i l i u m s a l t s (12) and a n i l i n e s ( 3 8 ) , as w e l l as p h e n o l i c e s t e r s ( 3 9 ) , a r e r e l a t i v e l y easy t o c l e a v e . A r y l l i n k a g e s ,

26

CHEMICAL REACTIONS ON POLYMERS


r e s o n a t i n g w i t h r e a c t i o n p r o d u c t s , make many non-metal atoms e a s i e r t o o x i d i z e . More e l e c t r o p o s i t i v e elements, such as s i l i c o n ( 4 0 ) , a r e e a s i l y d i s p l a c e d from phenyl by p r o t o n s and o t h e r L e w i s a c i d s through e l e c t r o p h i l i c a r o m a t i c s u b s t i t u t i o n . Furthermore, an a n t i p o d a l e l e c t r o n - w i t h d r a w i n g group can a c t i v a t e b e n z y l hydrogen on t h e polymer backbone f o r i n o p p o r t u n e i o n i c o r r a d i c a l s i d e - r e a c t i o n s ( 4 1 ) . On t h e o t h e r hand, i n s e r t i n g even one more methylene group between polymer and pendant would r e s u l t i n a primary bond n e i t h e r u n s t a b l e nor d e s t a b i l i z i n g towards n u c l e o p h i l e s , p e r m i t t i n g a c h e m i c a l l y more r o b u s t working m o l e c u l e w h i l e r e t a i n i n g t h e a t t r a c t i v e p h y s i c a l p r o p e r t i e s of p o l y s t y r e n e r e s i n . A d d i t i o n a l l y , e x t e n d i n g a r e a c t i v e s i t e f u r t h e r from polymer backbone improves c o n t a c t w i t h f r e e sub s t r a t e i n t h e l i q u i d phase (4-2, 43) , as w e l l as w i t h s i m i l a r f u n c t i o n a l neighbours t o enhance a c o o p e r a t i v i t y e f f e c t ( 4 4 ) , f o r an o v e r a l l i n c r e a s e i n c a t a l y t i c o r o t h e r a c t i o n . F o r example, among both polymers and f r e e m o l e c u l e s c o n t a i n i n g a p h e n e t h y l s u b s t r u c t u r e , i t has been observed t h a t : - 2 - p h e n e t h y l - h a l o p y r i d i n i u m s a l t s a r e u n u s u a l l y s t a b l e compared t o t h e i r b e n z y l , and even methyl o r e t h y l , c o u n t e r p a r t s (45, 4 6 ) ; - N-benzyl-N-phenethyl-N,N-dimethylammonium c h l o r i d e l o s e s predo m i n a n t l y b e n z y l when heated w i t h t h i o p h e n o x i d e , g i v i n g s t a b l e N,Ndimethylphenethylamine (47); - Ν,Ν-dimethylphenethylamine i t s e l f i s i n e r t t o f u r t h e r t r e a t m e n t w i t h hot a c e t i c anhydride (48); - s i m p l e c a r b o x y l i c a c i d s can be a l k y l a t e d (26) or p h o t o c h l o r i nated ( 4 9 ) , cinnamates p h o t o c r o s s l i n k e d (50) and t - b u t y l c a r b o n y l a t e d amino a c i d s d e p r o t e c t e d by a c i d o l y s i s ( 5 1 ) , w h i l e r e m a i n i n g e s t e r i f i e d t o p o l y s t y r e n e v i a dimethylene s p a c e r ; - q u a t e r n a r y phosphonium s a l t s connected through dimethylene s p a c e r s a r e s t a b l e r and more a c t i v e p h a s e - t r a n s f e r c a t a l y s t s than b e n z y l i c ones f o r r e a c t i o n o f c y a n i d e or t h i o l a t e w i t h a l k y l h a l i d e s ; r a t e s f u r t h e r improve w i t h even l o n g e r s p a c e r s (52, 5 3 ) ; - p h e n e t h y l - s u p p o r t e d p o l y s t y r y l t a r t a r a t e , f u n c t i o n n i n g as a s t a b l e s o l i d - p h a s e c h i r a l a u x i l i a r y f o r t h e S h a r p l e s s e p o x i d a t i o n of a l l y l i c a l c o h o l s , g i v e s h i g h e r c h e m i c a l and o p t i c a l y i e l d s than i t s b e n z y l i c analogue ( 5 4 ) ; I n t r o d u c t i o n o f dimethylene s p a c e r s onto p o l y s t y r e n e . Most of t h e t e c h n i q u e s and r e a c t i o n s d e s c r i b e d below, though o f t e n a p p l i c a b l e t o s o l u b l e p o l y s t y r e n e have been o p t i m i z e d u s i n g a 1% d i v i n y l b e n z e n e c r o s s l i n k e d g e l . To s i m p l i f y n o t a t i o n s , such a polymer h a v i n g 20% of i t s a r o m a t i c groups s u b s t i t u t e d w i t h f u n c t i o n a l group Ζ would be r e p r e s e n t e d as shown below and be g i v e n t h e molecul a r formula: ( C H ) .(C H ) .(C H Z) . 1 0

1 0

0 - 0 1

8

8

0 7 9

8

7

0 - 2 0

^CH-CH^ DF :

0.20

© - 1

2.


Dimethyiene Spacers


F u n c t i o n a l i z a t i o n through hydroxyethyl

27

group.

A d i m e t h y i e n e s p a c e r , t e r m i n a t e d by a v e r s a t i l e h y d r o x y l "handle", i s e a s i l y i n t r o d u c e d onto commercial c r o s s l i n k e d p o l y s t y r e n e r e s i n , w i t h o u t rearrangement (55) o r g r a f t i n g o f e t h y l e n e g l y c o l oligomer ( 5 6 ) , by t r e a t i n g the c o l d l i t h i a t e d polymer w i t h e x c e s s e t h y l e n e o x i d e ( 3 7 ) . The r e s u l t i n g ( h y d r o x y e t h y l ) p o l y s t y r e n e i s v i r t u a l l y i d e n t i c a l t o product made l e s s s i m p l y by c y a n a t i o n / h y d r o l y s i s / reduct i o n o f commercial ( c h l o r o m e t h y l ) p o l y s t y r e n e (52, 5 7 ) , o r by c o p o l y m e r i z a t i o n o f s t y r e n e , d i v i n y l b e n z e n e and t h e p r o t e c t e d f u n c t i o n a l monomer (26, 5 8 ) . P a s t e f f o r t s t o prepare p o l y s t y r e n e s p o s s e s s i n g l o n g e r f u n c t i o n a l i z e d o l i g o m e t h y l e n e s p a c e r s , by F r i e d e l - C r a f t s a l k y l a t i o n o f d i h a l i d e s , o r r e a c t i o n o f d i h a l i d e s o r c y c l i c halomium i o n s w i t h m e t a l l a t e d polymer, have g e n e r a l l y been accompanied by s i g n i f i cant a d d i t i o n a l c r o s s l i n k i n g o f polymer networks (53, 59, 6 0 ) . A r e c e n t e x c e p t i o n i s Tomoi e t a l ' s (61) a l k y l a t i o n o f s o l u b l e or c r o s s l i n k e d p o l y s t y r e n e w i t h w-bromoalkenes, c a t a l y z e d by 30 mol% t r i f l u o r o m e t h a n e s u l f o n i c a c i d , a p r o m i s i n g polymer f u n c t i o n a l i z a t i o n which i s r e p o r t e d t o proceed c o n t r o l l a b l y and w i t h o u t c r o s s l i n k i n g o r d e c o m p o s i t i o n o f polymer backbone. ( H y d r o x y e t h l y ) p o l y s t y r e n e has p r e v i o u s l y been f u r t h e r f u n c t i o n a l i z e d w i t h o u t b r e a k i n g the C-0 bond, by t r a n s e s t e r i f i c a t i o n ( 5 4 ) , o r by c a r b o x y l i c a c i d w i t h d i c y c l o h e x y l c a r b o d i i m i d e ( 5 1 ) , o r by a c i d anhydride ( 5 8 ) , o r by a c y l h a l i d e s (26, 49) or c h l o r o d i a l k y l p h o s p h i t e s o r phosphines (50) and a c i d a c c e p t o r . D e r i v a t i z i n g with 3 , 5 - d i n i t r o b e n z o y l c h l o r i d e i n p y r i d i n e , f o l l o w e d by n i t r o g e n a n a l y s i s , i s a r e l i a b l e way o f a s s a y i n g polymer-bound h y d r o x y l (37, 5 7 ) . A l k y l a t i n g and a r y l a t i n g r e a g e n t s (62) a l s o r e a c t w i t h p o l y m e r i c a l c o h o l i n a s t r a i g h t f o r w a r d manner. For ( h y d r o x y e t h y l ) p o l y s t y r e n e t o succeed as a v e r s a t i l e s y n t h e t i c i n t e r m e d i a t e ( 5 7 ) , t e c h n i q u e s must be e v o l v e d t o r e p l a c e oxygen by o t h e r atoms w h i c h may be more s u i t e d t o good f u n c t i o n o f f i n a l reagent. Such c o n v e r s i o n s must be c o m p l e t e l y q u a n t i t a t i v e , s i n c e unr e a c t e d , s i d e - r e a c t e d o r o v e r - r e a c t e d f u n c t i o n a l i t i e s cannot be removed from the s o l i d p r o d u c t , and may u l t i m a t e l y i n t e r f e r e w i t h i t s destined a c t i v i t y . N u c l e o p h i l i c s u b s t i t u t i o n a t 2-phenethyl under SN1 c o n d i t i o n s i s o c c a s i o n a l l y accompanied by a c u r i o u s s c r a m b l i n g o f both methylene c a r b o n s , a t t r i b u t e d by some t o t h e i n t e r m e d i a c y o f a n o n c l a s s i c a l three-membered carbonium i o n ; however, s i n c e t h e consequences a r e o n l y d e t e c t a b l e i n i s o t o p i c a l l y - l a b e l l e d m o l e c u l e s , the m e c h a n i s t i c d e t a i l i s moot ( 6 3 ) . The a l k e n e b e i n g c o n j u g a t e d , e l i m i n a t i o n c a n be a more i m p o r t a n t s i d e - r e a c t i o n o f p h e n e t h y l f u n c t i o n a l i t i e s than w i t h many o t h e r s . F o r t u n a t e l y , i t s o c c u r r e n c e d u r i n g f u n c t i o n a l group m o d i f i c a t i o n c a n o f t e n be a v o i d e d by c a r e f u l c h o i c e o f r e a c t i o n s t r a t e g y and c o n d i t i o n s ; f o r example, by choosing t o s y l a t e as a l e a v i n g group (64, 6 5 ) , and by w o r k i n g i n p o l a r s o l v e n t s a t low o r moderate t e m p e r a t u r e s w i t h s t r o n g n u c l e o p h i l e s t h a t are a l s o weak bases ( 6 6 ) . T h i s k i n d o f d e c o m p o s i t i o n i s n o t a problem f o r most t a r g e t polymer r e a g e n t s and c a t a l y s t s , whose f i n a l f u n c t i o n a l i t i e s are g e n e r a l l y poor l e a v i n g groups under b a s i c c o n d i t i o n s .

28



F u n c t i o n a l i z a t i o n t h r o u g h t o s y l o x y e t h y l _grou£. ( C h l o r o e t h y l ) p o l y s t y r e n e s and ( i o d o e t h y l ) p o l y s t y r e n e s a r e each prepared from t h e a l c o h o l by common r e a g e n t s i n a s i n g l e s t e p w i t h o u t c o m p l i c a t i o n s , but one-pot procedures f a i l t o produce c o m p l e t e l y pure bromide, which must be prepared from t h e t o s y l a t e by a s s i s t e d h a l i d e exchange ( 5 7 ) . The p r e p a r a t i o n of ( t o l u e n e s u l f o n y l o x y e t h y l ) p o l y s t y r e n e i t s e l f , i f performed i n i c e - c o l d p y r i d i n e as f o r t h e f r e e analogue ( 6 4 , 6 5 ) , r e q u i r e d a week t o complete (67) i f q u a t e r n a r y ammonium and o t h e r s i d e - p r o d u c t s (68) a r e t o be a v o i d e d . I n c o n t r a s t , w i t h n o n - n u c l e o p h i l i c d i i s o p r o p y l a m i n e (69) as a c i d a c c e p t o r i n s t e a d o f p y r i d i n e , ( h y d r o x y e t h y l ) p o l y s t y r e n e and t o l u e n e s u l f o n y l c h l o r i d e need o n l y be r e f l u x e d i n carbon t e t r a c h l o r i d e f o r a few hours t o g i v e t h e d e s i r e d t o s i c e s t e r as s o l e product i n q u a n t i t a t i v e y i e l d (57).

T o s y l a t e i s d i s p l a c e d by weak oxyanions w i t h l i t t l e e l i m i n a t i o n i n a p r o t i c s o l v e n t s , p r o v i d i n g a l t e r n a t i v e r o u t e s t o polymer-bound e s t e r s and a r y l e t h e r s . A l k o x i d e s , u n f o r t u n a t e l y , g i v e s i g n i f i c a n t f u n c t i o n a l y i e l d s of ( v i n y l ) p o l y s t y r e n e under t h e same c o n d i t i o n s . Phosphines and s u l f i d e s can a l s o be prepared from t h e a p p r o p r i a t e anions ( 5 7 ) , t h e l a t t e r l i p o p h i l i c enough f o r p h a s e - t r a n s f e r c a t a l y s i s f r e e from p o i s o n n i n g by r e l e a s e d t o s y l a t e . T r a n s f o r m a t i o n s t o polymer-bound amino compounds, which a r e o f t e n u s e f u l as l i g a n d s f o r m e t a l s i o n s or o t h e r f r e e s p e c i e s ( 6 7 ) , employ a wide s e l e c t i o n of o r g a n i c r e a c t i o n s . Quaternary ammonium s a l t s r e s u l t from h e a t i n g i s o l a t e d polymer t o s y l a t e w i t h t e r t i a r y amine; they may a l s o be prepared i n one s t e p from ( h y d r o x y e t h y l ) p o l y s t y r e n e and t o l u e n e s u l f o n y l c h l o r i d e and a t w o - f o l d e x c e s s of amine. Secondary amines, such as p y r r o l i d i n e , must be a l k y l a t e d w i t h c a r e : too p o l a r a s o l v e n t l e a d s t o p a r t i c i p a t i o n of a second nearby polymer-bound a l k y l a n t i n t h e f o r m a t i o n of a q u a t e r n a r y ammonium s a l t , a l o n g w i t h t h e d e s i r e d i m m o b i l i z e d t r i a l k y l amine. The except i o n , as seen above, i s d i i s o p r o p y l a m i n e , w h i c h r e f u s e s t o d i s p l a c e t o s y l a t e even i n t h e r e f l u x i n g pure amine, o r i n h o t d i m e t h y l formamide o r o t h e r p o l a r s o l v e n t , w h i l e m e t a l d i i s o p r o p y l a m i d e i s n o t o r i o u s as a p o w e r f u l n o n - n u c l e o p h i l i c base. However, carboxamide i s n o t d i f f i c u l t t o form from ( c a r b o x y m e t h y l ) p o l y s t y r e n e , a g a i n u s i n g t o l u e n e s u l f o n y l c h l o r i d e as condensing agent; t h i s can then be reduced t o ( d i i s o p r o p y l - e t h y l a m i n o e t h y l ) p o l y s t y r e n e , w h i c h i s of i n t e r e s t as a polymer-bound n o n - n u c l e o p h i l i c base .

2.

DARLING A N D FRÊCHET

Dimethyiene Spacers

29


An amide a n i o n w i l l p r e f e r s u b s t i t u t i o n i f i t s b a s i c i t y i s s u f f i c i e n t l y lowered by resonance, and can be u s e f u l where t h e n e u t r a l nitrogen i s unreactive or otherwise u n s u i t a b l e . Quaternizat i o n cannot be prevented i n the a l k y l a t i o n o f even f r e e n e u t r a l i m i d a z o l e , but an i m i d a z o l i d e a n i o n w i l l match w i t h o n l y one of t h e e l e c t r o p h i l i c s i t e s t e r m i n a t i n g dimethyiene spacer on p o l y s t y r e n e .

P h t h a l i m i d e and N - a l k y l - t o l u e n e s u l f o n a m i d e s a l t s a r e s i m i l a r l y a l k y l a t e d , and c a n f u r t h e r m o r e be c l e a v e d t o polymer-bound secondary and p r i m a r y amines r e s p e c t i v e l y ( 5 7 ) . P o t a s s i u m p y r r o l i d o n i d e g i v e s polymer-bound t e r t i a r y amide, of i n t e r e s t as a s o l i d c o s o l v e n t catalyst;

I n c o n t r a s t , the a c y c l i c a n i o n s of N-methyl acetamide and N-methyl-ot o l u a m i d e p r e f e r p r o t o n s t o carbon, f o r c i n g an a l t e r n a t i v e approach such as a c y l a t i o n o f ( m e t h y l a m i n o e t h y l ) p o l y s t y r e n e . I t i s unfort u n a t e too t h a t 4-N-methyl-pyridinamide, whose c o n j u g a t e a c i d p r e f e r s a l k y l a t i o n on r i n g r a t h e r than s i d e - c h a i n n i t r o g e n , i s s i m i l a r l y t o o b a s i c and/or h i n d e r e d f o r good y i e l d s o f i m m o b i l i z e d d i a l k y l a m i n o p y r i d i n e a c y l a t i o n c a t a l y s t from ( t o l u e n e s u l f o n y l o x y e t h y l ) p o l y s t y r e n e though not from ( b r o m o p r o p y l ) p o l y s t y r e n e (Fréchet, J.M.J.; D e r a t a n i , Α.; D a r l i n g , G.D.; Macromolecules i n p r e s s ) , whose s y n t h e s i s from s p e c i a l t y monomer i s however more d i f f i c u l t f o r the g e n e r a l o r g a n i c l a b o r a t o r y . N e v e r t h e l e s s , t h i s i l l u s t r a t e s one o f t h e few cases where a t h r e e carbon spacer shows s i g n i f i c a n t advantages over i t s two carbon a n a l o g . A number o f s y n t h e t i c approaches were undertaken towards a polymer-bound v e r s i o n o f the v e r s a t i l e N - m e t h y l - 2 - h a l o p y r i d i n i u m c o n d e n s a t i o n agent developped by Mukaiyama ( 7 0 ) , a p h e n e t h y l s u b s t i t u t e d analogue o f w h i c h shows e x c e p t i o n a l s t a b i l i t y and poten t i a l f o r r e c y c l a b i l i t y (71) . P o l y m e r i c a l k y l a t i o n o f 2 - c h l o r o p y r i d i n e o r 2-methoxypyridine was i n c o m p l e t e due t o h i n d r a n c e and d e a c t i v a t i o n o f h e t e r o c y c l i c n i t r o g e n , though the impure product s t i l l showed some d e h y d r a t i n g a b i l i t y ( 7 2 ) . A l t e r n a t i v e f o r m a t i o n o f 2p y r i d o n e by o x i d a t i o n (73) o f p y r i d i n i u m c h l o r i d e w i t h b a s i c f e r r i c y a n i d e was accompanied by s m a l l amounts o f c o l o u r e d r i n g - o p e n i n g (74) s i d e - p r o d u c t s . The same 2-pyridone c o u l d be o b t a i n e d by s t r o n g l y h e a t i n g p o l y m e r i c t o s y l a t e i n a l a r g e excess o f 2-methoxy p y r i d i n e as s o l v e n t , f o l l o w e d by h y d r o l y s i s . Conditions of f o r m a t i o n from the t r i m e t h y l s i l y l e t h e r of the 4-isomer, which ought t o d i s p l a y s i m i l a r behaviour by analogy w i t h the c o r r e s p o n d i n g f r e e m o l e c u l e s ( 7 5 ) , a r e m i l d e r and more e c o n o m i c a l . Treatment o f ( 4 p y r i d o n e t h y l ) p o l y s t y r e n e by t h i o n y l o r c a r b o n y l c h l o r i d e s , c o n c u r r e n t l y w i t h m e t a t h e s i s by t e t r a f l u o r o b o r a t e l i p o p h i l i c c o u n t e r i o n , a f f o r d s a s o l i d - p h a s e reagent c a p a b l e o f t r a n s f o r m i n g a m i x t u r e o f a l c o h o l and c a r b o x y l i c a c i d t o the e s t e r . However, the measured

30


(PVCH.CH.N Θ

P)-CH CH OTs 2

2

N

0

OTs

7 7

OCH

ν

3

J


CHP (P>CH CH N 2

2

/

a c t i v i t y of t h e polymer i s somewhat l e s s than hoped f o r , p r o b a b l y due to l a c k of a c c e s s i b i l i t y o f s i t e s deep w i t h i n a polymer m a t r i x i n s u f f i c i e n t l y s w o l l e n by o r g a n i c s o l v e n t s . Undoubtedly c o n d i t i o n s can s t i l l be o p t i m i z e d f o r t h i s p r o m i s i n g r e a g e n t .

D e l i b e r a t e p r o d u c t i o n of ( v i n y l ) p o l y s t y r e n e from ( t o l u e n e s u l f o x y e t h y l ) p o l y s t y r e n e o r ( h a l o e t h y l ) p o l y s t y r e n e s was b e s t a c c o m p l i shed by q u a t e r n i z a t i o n w i t h Ν,Ν-dimethylaminoethanol, f o l l o w e d by t r e a t m e n t w i t h base: b e t a - d e p r o t o n a t i o n i s encouraged i n t h e c y c l i c z w i t t e r i o n i c i n t e r m e d i a t e . R e a c t i o n was f a s t e r and c l e a n e r than w i t h o t h e r r e a g e n t s recommended ( 6 4 , 76, 77) f o r e l i m i n a t i o n s , such a s a l k o x i d e , d i a z a b i c y c l o u n d e c e n e or q u a t e r n a r y ammonium h y d r o x i d e ; t h i s new and e f f i c i e n t procedure may f i n d a p p l i c a t i o n elsewhere. H y d r o m e t a l l a t i o n or o t h e r a d d i t i o n s t o polymer-bound o l e f i n may prove u s e f u l s t e p s i n f u t u r e s y n t h e s e s by polymer m o d i f i c a t i o n . HO-CH p V C H C H C I + Me NCH CH OH — • ( p V C H 2

2

2

2

2

2

CI

2.

DARLING AND

31

Dimethyiene Spacers

FRÉCHET

EXPERIMENTAL SECTION I n f r a r e d s p e c t r a of KBr p e l l e t s were measured on a N i c o l e t 10DX FTIR. E l e m e n t a l a n a l y s e s were performed u s i n g P a r r p e r o x i d e bombs and by MHW L a b o r a t o r i e s ( P h o e n i x , AZ). (Hydroxyethyl)polystyrene. ( 1 0 1 0 ) 0 . 0 1 - ( 8 8 ) 0 . 5 7 ' ( 8 7 ) 0 . 4 2 (Bromo)polystyrene (20.00 g, 60 meq), o r i g i n a l l y prepared from commercial 1% c r o s s l i n k e d p o l y s t y r e n e r e s i n ( 3 7 ) , was suspended i n 500 ml dry benzene under n i t r o g e n . Into t h i s p a l e orange s u s p e n s i o n was i n j e c t e d 2.2 M nBuLi/hexane (60 ml, 132 meq), and the whole was s t i r r e d a t 60°C f o r 3 h o u r s . The l i q u i d phase was removed by f i l t r a t i o n , and the b e i g e r e s i d u e , s t i l l under n i t r o g e n , was suspended i n 200 ml dry THF, and c o o l e d t o -50°C, b e f o r e r e c e i v i n g condensed e t h y l e n e o x i d e by i n j e c t i o n (9.5 ml, 190 meq), t h e n b e i n g f u r t h e r s t i r r e d under a C 0 - c o o l e d condenser f o r 18 hours w h i l e g r a d u a l l y warming t o room t e m p e r a t u r e . The p a l e orangey e l l o w s u s p e n s i o n was t h e n f i l t e r e d , and t h e r e s i d u e washed 1 X THF:H 0 3:1, 1 X THF:H 0:conc HC1/H 0 8:2:1, 3 X H 0, 1 X THF, 2 X CH3OH, 1 X E t 0 , t h e n d r i e d under vacuum o v e r n i g h t : IR (KBr) peaks absent a t 1487, 1408, 1073, 1010, and 718 cm" f o r a r y l bromide p r e c u r s o r , and a t 1150-1060 cm" f o r ether side-products (CH -0-CH ); peaks p r e s e n t a t 3400 ( b r , CH 0-H) and 1046 ( s , CH -0) cm" . Anal.


C

H

C

H

C

H

B r

2

2

2

2

2

2

1

1

2

2

1

2

Calcd for ( C H 0, 5.47; B r , 0. 1 0

C

1 0

2

H

C

H

:

C

) l « ( 8 8 ) o 57·( 10 12°)o 4 2 ' Found: C, 86.51; H, 8.05; θ", 5.51; 0

8 6

0

5 8 ;

' Br,

H

7

' 0.

'

9 6 ;

(3,5-dinitrobenzoyloxyethyl)polystyrene. ( 10 10)0.01'( 8 8)0.57-( 10 12°)0.42 ( H y d r o x y e t h y l ) p o l y s t y r e n e (0.13 g, 0.44 meq),was heated w i t h 3 , 5 - d i n i t r o b e n z o y l c h l o r i d e (0.13 g, 0.55 meq) i n 2 ml dry p y r i d i n e a t 100°C under n i t r o g e n f o r 2 h o u r s , t h e n t h e y e l l o w - g r e e n s u s p e n s i o n was f i l t e r e d , and the r e s i d u e washed 3 X H 0, 1 X MEK, I X C H C 1 , 2 X CH3OH, and d r i e d under vacuum o v e r n i g h t , y i e l d i n g 0.20 g of a p a l e y e l l o w - b e i g e powder: IR (KBr) peaks absent a t 3400 and 1046 cm" f o r alcohol precursor; peaks p r e s e n t a t 3098 (w, A r - H ) , 1733 ( s , C=0), 1547 ( s , A r - N 0 ) , 1344 ( s , A r - N 0 ) , 1277 ( s , C0-0), 1164 (m, C0-0), 721 (m, A r - N 0 ) cm" . Anal. C

H

C

H

C

2

2

H

2

1

2

1

2

2

C

H

C

H

N

C a l c d f o r (C H )o.01·( 8 s)o.57-( 17 14 2°6)o.42 N, 5.66. 10

10

: Ν

'

5

·

7 6

·

F

o

u

n

d

:

(2,4-dinitrophenoxyethyl)polystyrene. ( 10 10)0.01-( 8 8)0.63'( 10 12°)0.36 ( H y d r o x y e t h y l ) p o l y s t y r e n e (0.51 g, 1.5 meq) was heated w i t h 2 , 4 - d i n i t r o f l u o r o b e n z e n e (0.30 ml, 2,4 meq) y e l l o w l i q u i d , and t r i e t h y l a m i n e (0.30 ml, 2.2 meq) i n 2 ml dry t o l u e n e a t 88°C f o r 40 h o u r s , then the dark r e d s u s p e n s i o n was f i l t e r e d , and the r e s i d u e washed 3 X acetone u n t i l f i l t r a t e was c o l o u r l e s s , 3 X H 0, 1 X MEK, I X C H C 1 , 2 X CH3OH, and d r i e d under vacuum o v e r n i g h t , y i e l d i n g 0.74 g of b r i g h t y e l l o w powder: IR (KBr) peaks absent a t 3400 and 1046 cm" for alcohol precursor; peaks C

H

C

H

C

H

2

2

1

2

32


p r e s e n t a t 1609 ( s , A r - N 0 ) , 1536 ( s , A r - N 0 ) , 1344 ( s , A r - N 0 ) , 1287 ( s , A r - N 0 ) , 1152 (m, C H - 0 A r ) , 1087 (m, C H - 0 A r ) , 833 (m, Ar-H) cm" for d e s i r e d product. 2

2

2

1

2

2

2

(Toluenesulfonyloxyethyl)polystyrene.


C

H

C

H

C

H

( 1 0 l o ) o . 0 1 - ( 8 9 ) o . 7 0 ' ( 1 0 1 2 % . 2 9 (Hydroxyethyl)polystyrene (10.35 g, 35 meq), t o l u e n e s u l f o n y l c h l o r i d e (8.4 g, 44 meq), and d r y d i i s o p r o p y l a m i n e (10 m l , 71 meq), were s t i r r e d t o g e t h e r i n 70 ml carbon t e t r a c h l o r i d e under n i t r o g e n a t room temperature, then heated t o r e f l u x f o r 6 hours. The p a l e y e l l o w s u s p e n s i o n was f i l t e r e d , and the r e s i d u e washed 1 X acetone, 3 X H 0 , 1 X MEK, I X C H C 1 , 2 X E t 0 , and d r i e d under vacuum o v e r n i g h t t o y i e l d 14.28 g of a v e r y p a l e y e l l o w powder: IR (KBr) peaks absent a t 3400 and 1046 cm" f o r a l c o h o l p r e c u r s o r ; peaks p r e s e n t a t 1363 ( s , S0-0C), 1180 ( d o u b l e t , s, S0-0C), 1098 (m, C - 0 ) , 964 ( s , S-0-C), 905 (m, S-0-C), 815 (m, S-0-C), 760 (m, S-0-C), 664 (m, A r - S 0 ) and 555 cm" ( s , A r S 0 ) cm" . A n a l . C a l c d f o r ( C H ) .(C H ) (C H S0 ) : S, 5,74; N, 0. Found: 9, 5,73; N, 0. 2

2

2

2

1

3

1

3

1 0

1 0

0 # 0 1

8

8

0 e 7 0

1 7

1 8

3

0 e 2 9

(3-nitrophenoxyethyl)polystyrene. C

H

C

H

C

H

S 0

( 10 10)0.01-( 8 8)0.70( 17 18 3)0.29 (Toluenesulfonyloxyethyl)poly s t y r e n e (0.51 g, 0.91 meq), m - n i t r o p h e n o l p a l e y e l l o w c r y s t a l s (0.25 g, 1.8 meq) and anhydrous potassium carbonate (0.26 g, 2.0 meq) were s t i r r e d i n 5 ml d r y dimethylformamide under n i t r o g e n a t 60°C f o r 16 hours. The r e d s u s p e n s i o n was f i l t e r e d , and t h e r e s i d u e washed 1 X acetome, 3 X H 0 , 1 X MEK, I X C H C 1 , 2 X CH3OH, and d r i e d under vacuum o v e r n i g h t t o g i v e a p a l e y e l l o w powder: IR (KBr) peaks absent a t 1363 and 1176 cm f o r t o s i c e s t e r p r e c u r s o r ; peaks p r e s e n t a t 1531 ( s , A r - N 0 ) , 1351 ( s , A r - N 0 ) , 1245 (m, C H - 0 A r ) , 1029 (m, C H ~ OAr) and 738 (m, Ar-H) cm" . A n a l . C a l c d f o r 2

2

2

2

2

2

2

1

C

H

C

H

C

H

N 0

( 10 10)0.01-( 8 8)0.70-( 16 15 3)0.29

:

N

2

' '

6 7

F

'

o

u

n

d

:

Ν

'

2

Λ

5

'

(N-pyridinium)polystyrene tosylate, c h l o r i d e . C

H

C

H

C

H

4

9 9

1

0

,

4

m e q

a n d

t o l u e n

( 10 10)0.01'( 8 8)0.75( 10 12%.24 ( · 8» ) s u l f o n y l c h l o r i d e (5.0 g, 26 meq) were suspended i n d r y p y r i d i n e (60 ml, 700 meq) c h i l l e d i n an i c e b a t h t o 0°C under n i t r o g e n . The m i x t u r e was a l l o w e d t o warm t o room temperature over 4 hours, then r e f l u x e d f o r 2 h o u r s , then c o o l e d and f i l t e r e d , and t h e r e s i d u e washed 3 X H 0 , 1 X MEK, I X C H C 1 , 1 X CH3OH, 1 X E t 0 , and d r i e d under vacuum o v e r n i g h t , y i e l d i n g 6.72 g of a peach-coloured powder: IR (KBr) peaks absent a t 1046 cm" f o r a l c o h o l p r e c u r s o r , a t 1363 and 1176 cm" f o r t o s y l e s t e r i n t e r m e d i a t e , and a t 1245 and 657 f o r a l k y l c h l o r i d e s i d e - p r o d u c t ; peaks p r e s e n t a t 3500 ( s , b r , absorbed H 0 ) , 1633 (m, p y r ) , 1582 (w, p y r ) , 1196 ( s , S0-0"), 1123 ( s . S0-0"), 1034 ( s , S0-0"), 1012 ( s , S0-0"), 682 (m, p y r ) and 569 cm" (m, A r S 0 " ) . The product was then washed w i t h c o n c e n t r a t e d h y d r o c h l o r i c a c i d , then 1 X HC1/H 0:THF 1:1, 1 X HC1/H 0:THF 1:4, 3 X H 0 , 1 X MEK, 1 X C H C 1 , 1 X CH 0H, 1 X E t 0 , 1 X hexane, and d r i e d under vacuum 2

2

2

2

1

1

2

+

1

3

2

2

2

2

3

2

2

2.

33

Dimethyiene Spacers


o v e r n i g h t , y i e l d i n g 5.99 g o f beige powder: IR (KBr) peaks absent a t 1196, 1123, 1034, 1012 and 569 cm" f o r t o s y l a t e a n i o n ; peaks s t i l l p r e s e n t a t 1633, 1582 and 682 cm" f o r p y r i d i n i u m n u c l e u s . Anal. 1

1

Calcd for ( C C I , 6.19.

1 0

H

)

1 0

C

0

0

H

C

H

l«( 8 8)o 7 5 ( 1 5 1 6

N C 1

) o 24

:C 1

6

» '

1 5

F

'

o

u

n

d

:

(N-pyrrolidinethyl)polystyrene. Chemical Reactions on Polymers Downloaded from pubs.acs.org by NANYANG TECHNOLOGICAL UNIV on 09/20/17. For personal use only.

C

H

C

H

C

H

S 0

( 10 10)0.01-( 8 8)0.70-( 17 18 3)0.29 (Toluenesulfonyloxyethyl)p o l y s t y r e n e (0.19 g,*0.34 meq), d r y p y r r o l i d i n e (0.032 ml, 0.38 meq) and anhydrous p o t a s s i u m c a r b o n a t e (o.050 g, 0.36 meq) were s t i r r e d i n 2 ml d r y p y r i d i n e under n i t r o g e n a t room temperature f o r 2 h o u r s , then s l o w l y warmed t o r e f l u x over 5 h o u r s . The red-orange s u s p e n s i o n was f i l t e r e d , and t h e r e s i d u e washed 3 X H 0 , 1 X MEK, I X C H C 1 , 1 X E t 0 , and d r i e d under vacuum o v e r n i g h t t o g i v e a y e l l o w - b e i g e powder: IR (KBr) peaks absent a t 1363 and 1176 c m for tosic ester p r e c u r s o r , and a t 1633, 1582 and 682 cm" f o r p y r i d i n i u m and 1196, 1123, 1034, 1012, 682 and 569 cm" f o r t o s y l a t e s i d e - p r o d u c t s ; peak p r e s e n t a t 2784 cm" ( C H ) . A n a l . C a l c d f o r 2

2

2

2

- 1

1

1

1

2

C

H

C

H

C

H

N

:Ν

3

( 1 0 1 0 ) 0 . 0 1 - ( 8 8 ) 0 . 7 0 - ( 1 4 1 9 ) 0.29 ' '

0 6

F

'

o

u

n

d

:

N

2

' '

9 8

'

(N-pyrrolidinonethyl)polystyrene. ( 10 10)0.01-( 8 9)0.794'( 17 18 3)0.196 (Toluenesulfonyloxyethyl)p o l y s t y r e n e (0.31 g, 0.42 meq), d r y p y r r o l i d i n o n e (0.051 ml, 0.66 meq) f r e s h l y - c r u s h e d potassium h y d r o x i d e (0.11 g, 2.0 meq) were r a p i d l y s t i r r e d i n 4 ml dry d i m e t h y l s u l f o x i d e under n i t r o g e n a t room temperature f o r 3 h o u r s , t h e n a t 60°C f o r 24 hours. The beige-brown s u s p e n s i o n was then f i l t e r e d , and t h e r e s i d u e washed 3 X H 0 , 1 X MEK, 1 X C H C 1 , 2 X CH3OH, and d r i e d under vacuum o v e r n i g h t , y i e l d i n g 0.26 g o f p a l e y e l l o w - b e i g e powder: IR (KBr) peaks absent a t 1363 and 1176 cm" f o r t o s i c e s t e r p r e c u r s o r ; peak p r e s e n t a t 1691 ( s , NC=0) cm" . A n a l . C a l c d f o r C

H

C

H

C

H

S 0

2

2

2

1

1

C

H

C

H

C

H

N

( 10 10)0.01-( 8 8)0.794-( 14 17 °)0.196

:

Ν

2

' -

1 8

'

F

o

u

n

d

:

N

2

' '

0 6

'

(3-nitrobenzoyloxyethyl)polystyrene. ( C

H

C

H

C

H

S 0

10 10)0.01-( 8 8)0.794'( 17 18 3)0.196 (Toluenesulfonyloxyethyl)p o l y s t y r e n e (0.41 g, 0.55 meq), n - n i t r o b e n z o i c a c i d p a l e grey powder (0.14 g, 0.83 meq) and anhydrous p o t a s s i u m c a r b o n a t e (0.17 g, 1.2 meq)were r a p i d l y s t i r r e d i n a m i x t u r e o f 4 ml d i m e t h y l s u l f o x i d e and 0.5 ml hexamethylphosphoramide under n i t r o g e n and warmed t o 60°C f o r 22 h o u r s . The p a l e brown s u s p e n s i o n was f i l t e r e d and washed 1 X a c e t o n e , 3 X H 0 ( r a p i d l y ) , 1 X MEK, I X C H C 1 , 1 X E t 0 , and d r i e d under vacuum o v e r n i g h t , y i e l d i n g 0.41 g of y e l l o w - b e i g e powder: IR (KBr) peaks absent a t 1363 and 1176 cm" f o r t o s i c e s t e r p r e c u r s o r , and a t 1046 cm" f o r h y d r o l y s i s s i d e - p r o d u c t ; peaks p r e s e n t a t 1727 ( s , C=0), 1535 ( s , A r - N 0 ) , 1351 ( s , N 0 ) , 1263 (m, C0-0), 1134 (Mm< C0-0) and 720 (m, Ar-H) cm" . A n a l . C a l c d f o r 2

2

2

2

1

1

2

2

1

C

H

C

H

C

H

N 0

( 10 10)0.01'( 8 8)0.794-( 17 15 4)0.196

:

N

l

' '

9 3

'

F

o

u

n

d

:

N

1

> '

8 7

'

34


ACKNOWLEDGMENTS F i n a n c i a l support of t h i s r e s e a r c h by the N a t u r a l S c i e n c e s and E n g i n e e r i n g R e s e a r c h C o u n c i l o f Canada i n the form o f an o p e r a t i n g g r a n t ( t o JMJF) and a p o s t - g r a d u a t e s c h o l a r s h i p ( t o GDD) i s g r a t e f u l l y acknowledged.


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2.

DARLING A N DFRÊCHET

Dimethyiene Spacers

35

28. Gilman, H.; Brook, A.G.; Miller, L.S.; J. Am. Chem. Soc., 1953, 75, 4531. 29. Chan, T.H.; Chang, E.; Vinokur, E.; Tetrahedron Lett., 1970, 1137. 30. Hartung, W.H.; Simonoff, R.; Org. React., 1953, 7, 263. 31. Erhardt, P.W.; Synth. Commun., 1983, 13, 103. 32. Newhome, G.R.; Majestic, V.K.; Sauer, J.D.; Org. Prep. Proced. Int., 1980, 12, 345. 33. Tweedie, V.L.; Allabash, J.C.; J. Org. Chem., 1961, 26, 3676. 34. Oda, R.; Hayashi, Y.; Tetrahedron Lett., 1967, 3141. 35. Fréchet, J.M.J.; Eichler, E.; Polym. Bull., 1982, 7, 345. 36. Ford, W.T.; Ref. 5, 155. 37. Farrall, M.J.; Fréchet, J.M.J.; J. Org. Chem., 1976, 41, 3877. Frechet, J.M.J.; Farrall, M.J.; "Chemistry and Properties of Crosslinked Polymers" (Labana, S.S., Editor), Academic Press, 59, 1977. 38. Chambers, R.A.; Pearson, D.E.; J. Org. Chem., 1963, 28, 3144. 39. March. J. "Advanced Organic Chemistry, Third Edition"; WileyInterscience, Toronto, 1985. 40. Chan, T.H.; Fleming, I.; Synthesis, 1979, 761. 41. Neckers, D.C.; Ref. 5, 107. 42. Brown, J.M.; Jenkins, J.Α.; J. Chem. Soc., Chem Comm., 1976, 458. 43. Molinari. H.; Montanari, F.; Quici, S.; Tundo, P.; J. Am. Chem. Soc., 1979, 101, 3920. 44. Tomoi, M.; Ikeda, M.; Kakiuchi, H.; Tetrahedron Lett., 1978, 3757. 45. Fischer, O.; Chem. Ber., 1899, 32, 1297. 46. M.Kametami, C,; Nomura, Y.; Chem. Pharm. Bull., 1960, 8, 741. 47. Kametami, T.; Kigasawa, K.l Hiiragi, M.; Wagatsuna, N.; Wakisaka, K.; Tetrahedron Lett., 1969, 635. 48. Tiffeneau, M.; Fuhrer, K.; Bull. Soc. Chim. Fr., 1914, 15, 162; Chem. Abstr. 8, 1567. 49. Bosch, P.; Font, J . ; Moral, Α.; Sanchez-Ferrando, F.; Tetrahedron, 1978, 34, 947. 50. Lieto, J . ; Milstein, D.; Albright, R.L.; Minkiewicz, J.V.; Gates, B.C.; CHEMTECH, 1983, (1), 46. 51. Camps, F.; Castells, J . ; Pi, J . ; An. Quim., 1974, 70, 848; Chem. Abstr. 83, 10018g. 52. Chiles, M.S.; Jackson, D.D.; Reeves, P.C.; J. Org. Cheml, 1980, 45, 2915. 53. Tomoi, M.; Ogawa, E.; Hosokama, Y.; Kakiuchi, H. J. Polym. Sci., Polym. Chem. Ed., 1982, 20, 3015, 3421. 54. Farrall, M.J.; Alexis, M.; Trecarten, M.; Nouv. J. Chim., 1983, 7, 449. 55. Cristol, S.J.; Douglass, J.R.; Meek, J.S.; J. Am. Chem. Soc., 1951, 73, 816. 56. Lebedev, N.N.; Baranov, Y.I.; Vysokomolekul. Spedin., 1966, 8, 198; Chem. Abstr., 65, 808g. 57. Darling, G.D.; Fréchet, J.M.J.; J. Org. Chem., 1986, 51, 2270. 58. Hirao, Α.; Takenada, K.; Yamaguchi, K.; Nakahama, S.; Yamazaki, N.; Polym. Comm., 1983, 24, 339. 59. Tundo, P.; Synthesis, 1978, 315. 60. McManus, S.P.; Olinger, R.D.; J. Org. Chem., 1980, 45, 2717. 61. Tomoi, M.; Kori, N.; Kakiuchi, H.; Reactive Polymers, 1985, 3, 341.

36

62. 63. 64. 65.


66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77.


Whalley, W.B.; J. Chem. Soc., 1950, 2241. Lee, C.C.; Spinks, J.W.T.; J. Am. Chem. Soc., 1960, 82, 138. Saunders, W.H.; Edison, D.H.; J. Am. Chem. Soc., 1960, 82, 138. Veeravagu, P.; Arnold, R.T.; Eigenmann, E.W.; J. Am. Chem. Soc., 1964, 86, 3072. March, J . ; Ref. 39, 895. Cheminat, Α.; Benezra, C.; Farrall, M.J.; Fréchet, J.M.J.; Can. J. Chem., 1981, 59, 1405. Tipson, R.S.; J. Org. Chem., 1944, 9, 235. Nagasaka, T.; Ito, H.; Ozawa, N.; Kosugi, Y.; Hamaguchi, F.; Yakugaku Zasshi, 1980, 100, 962. Mukaiyama, T.; Angew. Chem. Int. Ed. Engl, 1979, 18, 707. Paquette, L.A.; Nelson, N.A.; J. Org. Chem., 1962, 27, 1085. Darling, G.D.; Bald, E.; Fréchet, J.M.J.; Polym. Prep., Am. Chem. Soc., Div. Polym. Chem., 1983, 24, 354. Sugasawa, S.; Akahoshi, S.Y.; Suzuki, M.; J. Pharm. Soc. Japan, 1952, 72, 1273; Chem. Abstr., 1953, 47, 10539g. Decker, H.; Chem. Ber., 1903, 36, 2568. Liveris, M.; Miller, J . ; Aust. J. Chem., 1958, 11, 297. Nishikubo, T.; Iizawa, T.; Ashi, K.K.; Okawara, M.; Tetrahedron Lett., 1981, 22, 3873. Oediger, H.; Moller, F.; Angew. Chem., Int. Ed. Engl., 1967, 6, 76.

RECEIVED August

27, 1987

Dimethylene Spacers in Functionalized Polystyrenes - ACS

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