aryl Carboxylates - American Chemical Society

Chapter 8 o-(5-Thiono-2-imidazolin-2-yl)arylCarboxylates

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 20, 2016 | http://pubs.acs.org Publication Date: November 3, 1987 | doi: 10.1021/bk-1987-0355.ch008

Synthesis and Herbicidal Activity Michael A. Guaciaro, Marinus Los, Ronald K. Russell, Peter J . Wepplo, Barbara L. Lences, Peter C. Lauro, Philip L. Orwick, Kai Umeda, and Pierre A. Marc Agricultural Research Division, American Cyanamid Company, P.O. Box 400, Princeton, NJ 08540

The synthesis and herbicidal activities of various imidazolinthiones, in particular the thiono isosteres of imazapyr, imazethapyr and imaza methabenz are discussed. In the synthesis area it is shown that the imidazolinthione ring functions as an ortho-directing group in aromatic lithiations. In the biological activity area it is shown that re placement of the imidazolinone carbonyl with a thio carbonyl results in changes in weed toxicity and crop selectivity. The imidazolinones are a new class of herbicides discovered and being developed by American Cyanamid Company. Previous papers in the imidazolinone area (1-12) have discussed the preparation and biological activity of various aryl substituted imidazolinones, in particular imazapyr 1 (AC 243,997, registered by American Cyanamid under the trademarks ARSENAL, ASSAULT and CHOPPER), imazethapyr 2 (AC 263,499, discovered and being developed by American Cyanamid under the trademark PURSUIT) and imazamethabenz 3/4 (AC 222,293, discovered and being developed by American Cyanamid under the trademark ASSERT).

1 Imazapyr C

2 Imazethapyr

^ Y Y U

L

COOCH

3

^yCOOCHa +

N

/

Ο

C

H

A

^

V

Imazamethabenz 0097-6156/87/0355-0087$06.00/0 © 1987 American Chemical Society

In Synthesis and Chemistry of Agrochemicals; Baker, Don R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

SYNTHESIS AND CHEMISTRY OF AGROCHEMICALS


88

P r i o r i n v e s t i g a t i o n s have d e a l t w i t h the e f f e c t s on h e r b i c i d a l a c t i v i t y produced by changes i n the a r y l r i n g s , the a r y l r i n g subs t i t u e n t s , the n a t u r e o f the c a r b o n y l f u n c t i o n and the a l k y l groups on the i m i d a z o l i n o n e r i n g . These changes have a l l r e s u l t e d i n significant alterations in herbicidal activity and crop selectivity. A n o t h e r s i t e where m o l e c u l a r m o d i f i c a t i o n might produce changes i n h e r b i c i d a l a c t i v i t y and crop s e l e c t i v i t y i s the i m i d a z o l i n o n e c a r b o n y l . We reasoned t h a t r e p l a c i n g the i m i d a z o l i n o n e c a r b o n y l w i t h an i s o s t e r i c moiety, such as a t h i o c a r b o n y l , would a f f e c t such p r o p e r t i e s as i m i d a z o l i n o n e r i n g s i z e and bond a n g l e s , e l e c t r o n i c d i s t r i b u t i o n , p a r t i t i o n c o e f f i c i e n t s , pKa, chemical r e a c t i v i t y and hydrogen bonding c a p a c i t y and thus might have some e f f e c t on the a b s o r p t i o n , t r a n s l o c a t i o n and m e t a b o l i s m of the compounds i n q u e s t i o n , the b i o c h e m i c a l responses e l i c i t e d by the compounds and the r e s u l t i n g p l a n t s t r u c t u r a l changes. T h i s paper w i l l d i s c u s s the s y n t h e s i s and h e r b i c i d a l a c t i v i t y o f the i m i d a z o l i n t h i o n e c o u n t e r p a r t s of the h e r b i c i d e s shown above. Synthesis S y n t h e s i s o f the Thiono C o u n t e r p a r t of Imazapyr. I n our s y n t h e s i s o f i m i d a z o l i n t h i o n e s the most e f f i c i e n t p o i n t f o r i n t r o d u c t i o n o f the t h i o c a r b o n y l group proved to be a t the i n i t i a l stages of the s y n t h e s i s . Thus treatment o f amino amide 5 w i t h phosphorus p e n t a sulfide 14) a f f o r d e d thioamide 6, which was most e f f i c i e n t l y p u r i f i e d by p r e c i p i t a t i o n of i t s h y d r o c h l o r i d e s a l t . 1. Dioxane H N-

-C-NH

2

2

+ P S 2

-

5

2

2.HCI(g)

y\

-C—

H N-

NH

2

/ \

3. Et N 3

6

80-90%

The t h i o n o c o u n t e r p a r t o f imazapyr was prepared by t r e a t i n g 2 , 3 - p y r i d i n e d i c a r b o x y l i c a n h y d r i d e 7 w i t h thioamide 6 (THF, 60°C), a f f o r d i n g b o t h p o s s i b l e a d d i t i o n p r o d u c t s 8 and 9 as a 60:40 m i x t u r e . These r e g i o i s o m e r s were s e p a r a t e d by f r a c t i o n a l c r y s t a l l i z a t i o n . Treatment o f each i n t e r m e d i a t e w i t h excess sodium h y d r o x i d e f o l l o w e d by a c i d i f i c a t i o n a f f o r d e d t h i o i m i d a z o l i n y l a c i d s 10 o r 11. S i n c e p i c o l i n i c a c i d 11 was not a c t i v e i n the h e r b i c i d e s c r e e n below 500 g/ha preemergence and 250 g/ha postemergence and had no apparent crop s e l e c t i v i t y , i t w i l l not be d i s c u s s e d f u r t h e r . Ο

"

N

π °

T

H

^CONHf^V

/ V C O O H

6

f^T^O

F

60°C

-CSNH

C

^N^CONH4-CSNH

2

+

^ N ^ NC O O H S

1

60

:

40


2

8. GUACIARO ET AL. Treatment o f a c i d e s t e r 12.

o-(5-Tkiono-2-imidazolin-2-yl)aryl 10 w i t h

diazomethane

( 1 5 , 16) a f f o r d e d

methyl

CONH—J—CSNH2

COOH

oc' N^CONH-J-CSNH


Carboxylates 89

2

COOH

+

60 : 40 1. XS NaOH 2. HCI

1. XS NaOH 2. HCI

COOCH

^ X O O H

3

0 > v

s

10

COOH

11

S y n t h e s i s o f t h e Thiono I s o s t e r e o f Imazethapyr. The t h i o n o i s o s t e r e o f imazethapyr was p r e p a r e d i n the same f a s h i o n from 5ethyl-pyridine-2,3-dicarboxylic a n h y d r i d e 13. The r e s u l t i n g m i x t u r e o f r e g i o i s o m e r s 14 and 15 was t r e a t e d w i t h aqueous sodium h y d r o x i d e t o a f f o r d a c i d 16 a f t e r a c i d i f i c a t i o n and f r a c t i o n a l crystallization.

1.5NNaOH H 0 90°C 2

14/15 2. HCI



90

Treatment o f a c i d 16 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 (DCC) r e s u l t e d i n r i n g c l o s u r e t o the t r i c y c l e 17. Under these c y c l i z a t i o n c o n d i t i o n s none o f the o t h e r p o s s i b l e t r i c y c l e 18 i s d e t e c t e d . COOH

DCC CH CI 2

2


RT

17

18

Ring opening o f t r i c y c l e 17 w i t h sodium methoxide a f f o r d e d t h e m e t h y l e s t e r 19 i n q u a n t i t a t i v e y i e l d . The use o f these t r i c y c l i c i n t e r m e d i a t e s a l l o w s p r e p a r a t i o n o f a v a r i e t y o f e s t e r s s i m p l y by v a r y i n g t h e a l c o h o l employed ( 1 7 ) .

COOCH

3

cat NaH

17

vfr

MeOH RT 100%

S y n t h e s i s o f the Thiono C o u n t e r p a r t o f Imazamethabenz. The t h i o n o c o u n t e r p a r t o f imazamethabenz was prepared by t r e a t i n g 4-methy1p h t h a l i c anhydride (20) w i t h thioamide 6, a f f o r d i n g b o t h p o s s i b l e t h i o c a r b a m o y l m e t h y l p h t h a l a m i c a c i d s 21 and 22 i n 90% y i e l d as a 55:45 m i x t u r e .

CSNH

2

CSNH

2

22


8. GUACIARO ET AL.

o-(5~Thiono-2-imidazolin-2-yl)aryl

Carboxyiates 91

T h i s m i x t u r e underwent c y c l i z a t i o n i n sodium h y d r o x i d e t o i m i d a z o l i n t h i o n e s 23 and 24 i n 99% y i e l d . The m i x t u r e o f a c i d s 23 and 24 ^ X O O H

5N NaOH

C H

3

^ ^ C O O H

21/22

THF 60°C


5hr

Η Ν ^ γ γ _ 23

99%

S

HN.

'

2

Q

4

55 : 45

was t r e a t e d w i t h DCC t o a f f o r d t r i c y c l e s 25 and 26, which were e a s i l y c o n v e r t e d w i t h o u t p u r i f i c a t i o n t o e s t e r s 27 and 28 v i a t r e a t m e n t w i t h sodium methoxide.

23/24

catNaH MeOH

F

70% : 2 Steps

CH s^^.COOCH 3

^ ^ C O O C H a

3

- V • H N ^ A _ 27

CH

3

HN.

s

28

\

The R e g i o s p e c i f i c S y n t h e s i s o f 2 3 , 24, 27 and 28. We were i n t e r e s t e d i n t e s t i n g each o f the p r e v i o u s l y mentioned r e g i o i s o m e r s 23, 24, 27 and 28 i n d i v i d u a l l y i n o u r greenhouse s c r e e n s . Since chromatographic s e p a r a t i o n o r f r a c t i o n a l c r y s t a l l i z a t i o n o f these r e g i o i s o m e r s proved t o be t e d i o u s and i n e f f i c i e n t and we wished t o determine i f t h e i m i d a z o l i n t h i o n e r i n g , l i k e t h e i m i d a z o l i n o n e r i n g , was an o r t h o - d i r e c t i n g group i n a r o m a t i c l i t h i a t i o n s ( 18, 19), we embarked on t h e r e g i o s p e c i f i c s y n t h e s i s o f t h e above isomers. Treatment o f meta- o r p a r a - t o l u y l c h l o r i d e (29 o r 30) w i t h t h i o a m i d e 6 i n t h e presence o f excess t r i e t h y l a m i n e a t -60°C a f f o r d e d the t h i o c a r b a m o y l t o l u a m i d e s 31 o r 32 w h i c h , when t r e a t e d w i t h excess sodium h y d r o x i d e , c y c l i z e d t o the i m i d a z o l i n t h i o n e s 33 o r 34.

R

'XX

2

R '^ ^COCI v

2

29 30

R H R = CH R = CH R = H 1 =

1

2

3

3

2

2 ELN

I

H N-L-CSNH

·

Λ

2

— -

THF -60°C

R ,

Xi

I

FV^^CONH-J— 31 32

-CSNHp

R.j = H R = CH 2

R.j = ChLj R

= 2

H


3


92

R l

5equiv10%NaOH 3 1

0

R

32

THF

> k ^ ^ N

R 2

68°C

HN. Downloaded by UNIV OF CALIFORNIA SAN DIEGO on January 20, 2016 | http://pubs.acs.org Publication Date: November 3, 1987 | doi: 10.1021/bk-1987-0355.ch008

S 33

R

34

R = C H R = H 50%from 30

1 =

H R = CH3

'

2

1

3

47% from 29

2

Treatment o f 33 w i t h two e q u i v a l e n t s o f s e c - b u t y l l i t h i u m i n the presence o f t e t r a m e t h y l e t h y l e n e d i a m i n e (TMEDA) a t -70°C w i t h g r a d u a l warming t o -45°C, f o l l o w e d by a carbon d i o x i d e quench a t 70°C and a c i d i f i c a t i o n a f f o r d e d the a c i d 23 i n 62% y i e l d . 1. 2sec-BuLi 2 TMEDA

A

THF -70°Cto-45°C

HN^/V

33

S

^ ^

Χ

)

Ο

Η

ΗΤΙ^Λ

3. H 0 * 3

'

(

62%

23

S

HOOC '

HN^/V

trace 35

S

While i t i s p o s s i b l e f o r l i t h i a t i o n o f 33 t o occur between the m e t h y l group and the i m i d a z o l i n t h i o n e r i n g , o n l y t r a c e amounts o f the r e s u l t i n g s t e r i c a l l y crowded a c i d 35 c o u l d be seen i n t h e NMR spectrum o f the u n p u r i f i e d p r o d u c t . Similarly, s u b s t r a t e 34 p r o v i d e d the a c i d 24 i n 39% y i e l d a f t e r r e c r y s t a l l i z a t i o n .

1. 2sec-BuLi 2 TMEDA

A c i d s 23 and 24 were c a r r i e d on, v i a the t r i c y c l e s 25 and 26, to the m e t h y l e s t e r s 27 and 28 r e s p e c t i v e l y . The y i e l d o f e s t e r 28 was low s i n c e i t was prepared from impure a c i d 24.


8. GUACIARO ET AL.

o-(5-Thiono-2-imidazolin'2-yl)aryl

Carboxylates 93

Ο


23 24

R R

1

1

=

=

H R2 = C H

3

CH

25

RÏ = H

26

R =CH

R2 =

CH

3

3

R ^ H

1

3

27

Fl, = H

R = H R2 = 1

CH

3

39% from 23 28

R

1=

CH R2=H 3

18% from 24

Biological Activity The i m i d a z o l i n t h i o n e s were t e s t e d i n the greenhouse p r e - and p o s t emergence on a number o f weeds and c r o p s . The g r a s s e s were b a r n y a r d g r a s s , green f o x t a i l , p u r p l e nutsedge, w i l d o a t s and q u a c k g r a s s . The b r o a d l e a v e s were f i e l d bindweed, morning g l o r y , w i l d mustard, v e l v e t l e a f , ragweed and m a t r i c a r i a . The c r o p s were s p r i n g b a r l e y , sugar b e e t s , c o r n , c o t t o n , r i c e , s u n f l o w e r , s p r i n g wheat and soybeans. The p h e n y l analogs were t e s t e d on a l l f i v e g r a s s e s w h i l e the p y r i d y l compounds were t e s t e d on a l l b u t green f o x t a i l . The benzoates were t e s t e d on a l l o f the b r o a d l e a v e s except ragweed and matricaria. The n i c o t i n a t e s were t e s t e d on a l l the b r o a d l e a v e s e x c e p t w i l d mustard. I n a l l i n s t a n c e s weed c o n t r o l i s d e f i n e d as >_90% t o x i c i t y and s a f e t y towards c r o p s as £10% t o x i c i t y . F i g u r e s 1 t o 8 compare the i m i d a z o l i n t h i o n e s t o the i m i d a z o l i n o n e s a t v a r i o u s r a t e s o f a p p l i c a t i o n p r e - and postemergence. F i g u r e 1 compares t h i o n e 10 t o imazapyr (1) a t 32 g/ha postemergence w h i l e F i g u r e 2 compares the preemergence d a t a f o r the m e t h y l e s t e r (36) o f imazapyr t o i t s t h i o n e c o u n t e r p a r t 12 a t 32 g/ha. I n the imazaethapyr a r e a F i g u r e 3 compares the preemergence d a t a f o r i m a z e t h a p y r (2) t o the d a t a f o r i m i d a z o l i n t h i o n e 16 a t 63 g/ha. I n the imazamethabenz a r e a F i g u r e 4 compares the postemergence d a t a a t 500 g/ha f o r t h e a c i d m i x t u r e s 23/24 and 37/38 w h i l e F i g u r e 5 compares the postemergence d a t a f o r 23/24 and 37/38 a t 500 g/ha. F i g u r e 6 compares the preemergence d a t a f o r the m i x t u r e o f m e t h y l e s t e r s 27/28 and imazamethabenz 3/4 a t 500 g/ha. Figure 7 presents a comparison o f the b i o l o g i c a l data f o r i m i d a z o l i n o n e 37 and i t s i m i d a z o l i n t h i o n e c o u n t e r p a r t 23 on s p e c i f i c weeds and c e r e a l s p o s t emergence a t 250 g/ha. I n F i g u r e 8 the preemergence d a t a a t 500 g/ha f o r i m i d a z o l i n t h i o n e 27, i m i d a z o l i n o n e 4 and imazamethabenz 3/4 i s compared. Structure-Activity The Imazapyr A r e a . When imazapyr (1) i s compared t o i t s i m i d a z o l i n t h i o n e c o u n t e r p a r t 10 b o t h p r e - and postemergence, imazapyr proves to be a more e f f e c t i v e t o t a l v e g e t a t i o n c o n t r o l agent. As F i g u r e 1 shows, w h i l e 10 i s comparable t o imazapyr a t 32 g/ha postemergence i n c o n t r o l l i n g g r a s s e s and i n j u r i n g c r o p s , i t i s l e s s e f f e c t i v e i n c o n t r o l l i n g b r o a d l e a v e s . Thione 10 i s much l e s s


94



a c t i v e than imazapyr preemergence a t 32 g/ha i n a l l three categories. Comparison of the e f f e c t i v e n e s s of the m e t h y l e s t e r (36) o f imazapyr as a t o t a l v e g e t a t i o n c o n t r o l agent to t h i o n e 12 ( F i g u r e 2) shows t h a t i n t r o d u c t i o n o f a t h i o c a r b o n y l does not improve weed t o x i c i t y , p r o v i d i n g a compound (12) which i s comparable t o 36 i n terras o f o v e r a l l t o t a l v e g e t a t i o n c o n t r o l a t 32 g/ha preemergence. At 32 g/ha postemergence t h i o n e 12 i s much l e s s e f f e c t i v e than 36 i n c o n t r o l l i n g weeds. The Imazethapyr A r e a . As F i g u r e 3 shows, t h i o n e 16 i s l e s s e f f e c t i v e o v e r a l l than imazethapyr (2) i n preemergence weed c o n t r o l on soybeans, p a r t i c u l a r l y i n the b r o a d l e a v e s , where 16 i s i n a c t i v e on morning g l o r y and ragweed. I m i d a z o l i n t h i o n e 16 i s a l s o more i n j u r i o u s to soybeans than imazethapyr and shows no o t h e r c r o p selectivity. Thione 16, postemergence a t the same r a t e , i s e s s e n t i a l l y i n a c t i v e compared t o imazethapyr. The m e t h y l e s t e r (19) o f t h i o n e 16 i s e s s e n t i a l l y i n a c t i v e b o t h p r e - and postemergence a t 63 g/ha. S t r u c t u r e - A c t i v i t y i n the Imazamethabenz A r e a . In t h i s category, the m i x t u r e of i m i d a z o l i n o n e s 37/38 i s more e f f e c t i v e i n c o n t r o l l i n g g r a s s e s and b r o a d l e a v e s than the t h i o n e m i x t u r e 23/24. Preemergence a t 500 g/ha ( F i g u r e 4) b o t h 23/24 and 37/38 are q u i t e i n j u r i o u s to c r o p s . However, a t 500 g/ha postemergence, as F i g u r e 5 shows, t h i o n e m i x t u r e 23/24 i s l e s s i n j u r i o u s t o c r o p s than 37/38, showing s a f e t y on c o r n , wheat and r i c e . The m i x t u r e 23/24 i s l e s s e f f e c t i v e than 37/38 i n c o n t r o l l i n g b r o a d l e a v e s and o n l y c o n t r o l s w i l d o a t s i n the g r a s s c a t e g o r y . In t h i s i n s t a n c e i n t r o d u c t i o n o f the t h i o c a r b o n y l group imparts some crop s e l e c t i v i t y t o 23/24. The t h i o n e c o u n t e r p a r t s o f imazamethabenz 3/4 o n l y show h e r b i c i d a l a c t i v i t y and crop s e l e c t i v i t y i n the c e r e a l s a r e a b u t are l e s s e f f e c t i v e than imazamethabenz i n c o n t r o l l i n g s e l e c t e d weeds on c e r e a l s preemergence, as F i g u r e 6 shows. The i n t r o d u c t i o n o f a t h i o c a r b o n y l group a l l o w s green f o x t a i l t o c o m p l e t e l y d e t o x i f y the m i x t u r e 27/28. In postemergence t e s t s , 27/28 a l s o does not o u t p e r f o r m imazamethabenz i n terms of weed c o n t r o l i n c e r e a l s . In i n d i v i d u a l t e s t s the meta- and p a r a - t o l u i c a c i d s 37 and 38 were shown to be i n j u r i o u s to crops b o t h p r e - and postemergence. However, i m i d a z o l i n t h i o n e 23 i s s e l e c t i v e l y d e t o x i f i e d by c e r e a l s and i s more e f f e c t i v e i n c o n t r o l l i n g s e l e c t e d weeds on c e r e a l s , e s p e c i a l l y postemergence ( F i g u r e 7 ) . U n f o r t u n a t e l y , 23 f a i l s t o c o n t r o l green f o x t a i l and thus f a i l s to p r o v i d e a u s e f u l new range of a c t i v i t y on c e r e a l s . Of the two r e g i o i s o m e r s 27 and 28 o n l y p a r a - t o l u a t e 27 shows any s i g n i f i c a n t preemergence a c t i v i t y and i t s s e l e c t i v i t y i s c o n f i n e d to c e r e a l s . As F i g u r e 8 shows, t h i o n e 27, i m i d a z o l i n o n e 4 and imazamethabenz (3/4) show l i t t l e d i f f e r e n c e i n o v e r a l l preemergence weed c o n t r o l w i t h 27 and imazamethabenz b e i n g s a f e on c e r e a l s . A g a i n , i n t r o d u c t i o n of a t h i o c a r b o n y l group does not improve the h e r b i c i d a l e f f e c t on green f o x t a i l . I n postemergence t e s t s 27 i s s l i g h t l y l e s s e f f e c t i v e than imazamethabenz i n c o n t r o l l i n g s e l e c t e d weeds on c e r e a l s .



8. GUACIARO ET AL.

o-(5-Thiono-2-imidazolin-2-yl)aryl

Carboxylates 95

% Control

F i g u r e 1. Comparison o f 1 t o 10 a t 32 g/ha postemergence.

F i g u r e 3. Comparison o f 2 t o 16 a t 63 g/ha preemergence.


96


COOH

Ri R2

H

Crops

' f r

N


23 R 1 - H R 2 « C H 24

Grasses

3

R1«CH R2«H 3

COOH Broadleaves

20

40 60 % Control

80

100 37 R1 - H R2 = CHj 38 R1-CH R2 = H 3

F i g u r e 4.

Comparison emergence.

o f 23/24 t o 37/38 a t 500 g / h a

pre

Crops 23 Grasses

RI.HR2.CH3

24 R 1 » C H R 2 - H 3

R K / W

C

O

O

H

Broadleaves τ

20

F i g u r e 5.

1

1

1

1

40 60 % Control

Comparison emergence.

1

r

80

100 37

R 1 » H R2.CH3

38

RI-CH3

o f 23/24 t o 37/38 a t 500 g / h a

post-


R2-H


8. GUACIARO ET AL.

o-(5-Th\ono-2-\midazolin-2-yl)aryl

Carboxylatts

27

R1-HR2-CH

28

RI-CH3R2-H

F i g u r e 6. Comparison o f 3/4 t o 27/28 a t 500 g/ha p r e emergence.

% Control

F i g u r e 7. Comparison o f 23 t o 37 a t 250 g/ha postemergence.


3



F i g u r e 8.

Comparison o f 27 and 4 t o 3/4 a t 500 g/ha p r e emergence ·


GUACIARO ET AL.

o~(5- Thiono-2-imidazol\n-2-yl)aryl

Carboxylate


Literature Cited 1. Los, M.; Ciarlante, D. R.; Ettinghouse, Ε. M.; Wepplo, P. J . , 184th National Meeting, American Chemical Society, 1982; PEST 21. 2. Los, M.; Orwick, P. L.; Russell, R. K.; Wepplo, P. J . , 185th National Meeting, American Chemical Society, 1983; PEST 87. 3. Los, M., 186th National Meeting, American Chemical Society, 1983; PEST 65. 4. Los, Μ., American Chemical Society Symposium Series 1984, 255, 29-44. 5. Los, M.; Wepplo, P. J . ; Russell, R. K.; Lences, B. L.; Orwick, P. L., 188th National Meeting, American Chemical Society, Philadelphia, PA, 1984. 6. Los, M.; Wepplo, P. J . ; Parker, Ε. M.; Hand, J. J . ; Russell, R. K.; Barton, J. M.; Withers, G,; Long, D. W., 10th Inter national Congress of Heterocyclic Chemistry, University of Waterloo, Ontario, Canada, August 11, 1985. 7. Los, M. U.S. Patent 4 188 487, 1980. 8. Los, M. U.S. Patent 4 297 128, 1981. 9. Los, M. Eur. Patent 41 623, 1981. 10. Los, M. Eur. Patent 133 310, 1985. 11. Los, M. Eur. Patent 133 311, 1985. 12. Los, M. Eur. Patent 166 907, 1986. 13. Reid, Ε. E. Organic Chemistry of Bivalent Sulfur; Chemical Publishing Company: New York, 1962; Vol IV. 14. Walter, W.; Voss, J. The Chemistry of Amides; Wiley: New York, 1970; pp 383-475. 15. de Boer, Th. J . ; Backer, H. J. Org. Syn. Coll Vol. 4, 1963, 943. 16. de Boer, Th. J . ; Backer, H. J. Rec. trav. chim. des Pay-Bas, 1954, 73, 229. 17. Los, M. U.S. Patent 4 544 754, 1985. 18. Los, M.; Russell, R. K.; Lauro, P. C.; Lences, B. L.; Hadden, S. K.; Brady, T. E.; Wepplo, P. J . , 10th International Congress of Heterocyclic Chemistry, University of Waterloo, Ontario, Canada, August 11, 1985. 19. Los, M.; Russell, R. K.; Lauro, P. C.; Lences, B. L.; Lies, T. Α.; Parker, Ε. M.; Wepplo, P. J . , ibid, August 12, 1985. RECEIVED August

31, 1987


aryl Carboxylates - American Chemical Society

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