Synthesis, Insecticidal Activity, and Anticholinesterase Activity of Some

Chapter 22 Synthesis, Insecticidal Activity, and Anticholinesterase Activity of Some Oxadiazolones 1

J. R. Sanborn , Kurt H. Pilgram, E. J. Ayers, and Richard D. Skiles

Downloaded by UNIV LAVAL on May 9, 2016 | http://pubs.acs.org Publication Date: November 3, 1987 | doi: 10.1021/bk-1987-0355.ch022

Biological Sciences Research Center, Shell Agricultural Chemical Company, Modesto, CA 95352 This report summarizes the synthesis, insecticidal activity, and anticholinesterase activity of some novel N-dihydrobenzo furanyl oxadiazolones. The compounds were primarily aphicides with reduced activity on houseflies, corn earworms and two -spotted spider mites. Some of these compounds were potent anticholineterases (I values 1-10x10 M) that were slowly reversible. There was little relationship between in vitro anticholinesterase activity and in vivo activity. -8

50

A synthesis program was initiated to optimize the insecticidal activity of the following molecules that are related to RP 32861, a substance reported to be insecticidal against sucking insects(1).

H o u s e f l y TI*=6

Aphid TI*=4

RP 32861

* P a r a t h i o n TI=100 The new m o l e c u l e s had t h e f o l l o w i n g g e n e r a l i z e d

structure(2):

Where X - H o r C H Y = H, h a l o g e n o r a l k y l Ζ - alkoxy, aryloxy a l k y l or a r y l 3

Current address: Ε. I. de Pont de Nemours & Co., Wilmington, DE 19898 0097-6156/87/0355-0241$06.00/0 © 1987 American Chemical Society

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

SYNTHESIS AND CHEMISTRY OF AGROCHEMICALS

242


Synthesis The s y n t h e s i s o f these molecules can be broken down i n t o two p a r t s . The f i r s t segment c o n s i s t e d o f p r e p a r a t i o n o f t h e d i h y d r o b e n z o f u r a n y l h y d r a z i n e s from which t h e o x a d i a z o l o n e s were e v e n t u a l l y prepared. These h y d r a z i n e s were prepared as f o l l o w s : t h e ap p r o p r i a t e o - n i t r o p h e n o l was t r e a t e d w i t h t h e d e s i r e d a l l y l i c h a l i d e under a l k a l i n e c o n d i t i o n s t o y i e l d an a l l y l e t h e r . T h i s was r e arranged and r i n g - c l o s e d a t e l e v a t e d temperatures under a c i d i c conditions to y i e l d the 7 - n i t r o s u b s t i t u t e d dihydrobenzofuran. R e d u c t i o n w i t h hydrogen over p a l l a d i u m on carbon and d i a z o t i z a t i o n of t h e 7-aminodihydrobenzofuran w i t h sodium n i t r i t e y i e l d e d a diazonium s a l t t h a t was reduced w i t h sodium d i t h i o n i t e t o g i v e t h e 7-hydrazinodihydrobenzofuran sulfonic a c i d . Treatment o f t h i s s u l f o n i c a c i d i n ethanol w i t h h y d r o c h l o r i c a c i d y i e l d e d the d e s i r e d 7-hydrazinodihybenzofurans· C o n s t r u c t i o n o f t h e o x a d i a z o l o n e r i n g from t h e aforementioned h y d r a z i n e i s i l l u s t r a t e d below: *ArNHNH

2

+

C1C(0)R

ArNHNHC(0)R

(I)

ArNNHC(0)R I C(0)C1

(ID

-HCL (I)

+

C1 C(0) 2

-HCL A (Π)

-HCL

\

c—ο x

1 I Ar *Ar = 7-substituted benzofuran R « alkoxy, a r y l or a l k y l

Treatment of the 7-hydrazinodihydrobenzofuran with either a c h l o r o f o r m a t e o r an a c y l c h l o r i d e i n t h e presence o f N , N - d i i s o p r o p y l e t h y l a m i n e y i e l d e d t h e N - a c y l a t e d p r o d u c t . Treatment o f t h i s intermediate N-acylated 7-dihydrobenzofuranyl hydrazine with phosgene f o l l o w e d by treatment o f t h e i n t e r m e d i a t e c h l o r o c a r b o n y l compound w i t h a n e q u i v a l e n t o f b a s e y i e l d e d t h e i n s e c t i c i d a l m o l e c u l e s t o be d i s c u s s e d i n t h i s r e p o r t . Insecticidal Activity The m o l e c u l e s o f t h i s r e p o r t were e v a l u a t e d on f o u r i n s e c t s : t h e h o u s e f l y , Musca domestica (M.d.), t h e pea a p h i d , A c y r t h o s i p h o n p i s u m ( A . p . ) , t h e c o r n e a r w o r m , H e l i o t h i s z e a ( H . z . ) a n d twos p o t t e d s p i d e r m i t e T r i t i c u m u r t i c a e ( T . u . ) . U s i n g p a r a t h i o n as t h e s t a n d a r d f o r each i n s e c t , i t i s g i v e n a v a l u e o f 100, so o t h e r m o l e c u l e s w i t h t o x i c i t y i n d e x v a l u e s ( T I ) o f 100 a r e as t o x i c as parathion. H i g h e r T I v a l u e s r e p r e s e n t g r e a t e r t o x i c i t y and so forth.


22.

SANBORN ET AL.

T a b l e 1.

Synthesis and Activity of Some Oxadiazolones

E f f e c t o f R i n g S u b s t i t u e n t s a t 4 - P o s i t i o n on t h e T o x i c i t y of D i h y d r o b e n z o f u r a n y l O x a d i a z o l o n e s


Ο

T o x i c i t y Index (parathion=100) A.p. H.z. M.d. 34 714 68 23 18 988 13 91 36 + 554 2 36 13 546

Structure X Η CH. i-C.H Cl F 3

7

T.u. 53 38 37 20 2

T a b l e 1 c o n t a i n s i n s e c t i c i d a l t o x i c i t y i n f o r m a t i o n on f i v e com pounds which d i f f e r o n l y i n t h e i r s u b s t i t u e n t s a t t h e 4 - p o s i t i o n of the d i h y d r o b e n z o f u r a n y l r i n g . W i t h t h e e x c e p t i o n o f a p h i d s , the most b r o a d l y a c t i v e compound was u n s u b s t i t u t e d a t t h i s p o s i t i o n . Other s u b s t i t u e n t a t t h i s s i t e had no enhancing e f f e c t and i n some cases (CI on h o u s e f l i e s and c o r n earworms and F on m i t e s ) a s t r o n g d e l e t e r i o u s e f f e c t r e s u l t e d . The o n l y case where a s u b s t i t u e n t , CH^, i n c r e a s e d t h e a c t i v i t y was w i t h a p h i d s . T a b l e 2.

E f f e c t s o f M e t h y l S u b s t i t u e n t s a t the 2- and 4 - P o s i t i o n s on t h e I n s e c t i c i d a l T o x i c i t y o f t h e Dihydrobenzofuranyl Oxadiazolones Ο

CH 0' 3

Structure X Η CH Η CH 0

3

3

Y H H CH. CH3

T o x i c i t y Index (parathion=100) H.z. A.p. M.d. 19 22 243 34 714 68 16 479 11 23 18 988

T.u. 20 53 0 38

M a x i m a l a c t i v i t y f o r a l l i n s e c t s was o b t a i n e d when t h e mole c u l e s c o n t a i n e d two m e t h y l groups a t t h e 2 - p o s i t i o n o f t h e d i h y d r o benzofuranyl r i n g . I f t h e m o l e c u l e had o n l y one methyl group a t the 2 - p o s i t i o n and m e t h y l group a t t h e 4 - p o s i t i o n , t h i s s u b s t i t u e n t p a t t e r n c o n f e r r e d i n f e r i o r t o x i c i t y as compared t o m o l e c u l e s con t a i n i n g gem d i m e t h y l s a t t h e 2 - p o s i t i o n o f t h e d i h y d r o b e n z o f u r a n y l r i n g . See Table 2.


243


244 Table 3.

Effect of A l k y l or Aryl Substituents at the 5-Position of Oxadiazolone Ring on the I n s e c t i c i d a l Toxicity

C H a ^ C H î

R CH

C H 3


C

A.p.

0

0

0

0

0

1

0

0

0

0

0

0

3

5

H

6 5

H.z.

T.u.

M.d»

E x a m i n a t i o n of the data i n Table 3 c l e a r l y p o i n t s out the n e c e s s i t y of having some type of an alkoxy subs t i t u e n t i n the 5-position of the oxadiazolone ring as most of the compounds were inactive against the insects i n the primary screen. Only one of the compounds, (R=C«jH^) had marginal a c t i v i t y (TI=1) a g a i n s t aphids· Table 4.

E f f e c t of a Phenoxy Group at 5-position of the Oxadiazolone Ring on I n s e c t i c i d a l Toxicity

C H J ^ ^ C H J

X

M.d.

A.p.

H 2-F 4-C1 3,4,5

0 0 0 0

20 8 6 8

CH

H.z. 0 + 0 0

T.u. 0 0 0 0

The presence of a phenoxy or a substituted phenoxy group at the 5-position of the oxadiazolone ring yields molecules that possess low l e v e l a c t i v i t y on aphids i n the primary s c r e e n . The most active compound i s the unsubstituted phenyl molecule (TI-20), and any other substituent on the phenyl ring (2F, 4-C1 or 3,4,5-CH^) reduces the a c t i v i t y on aphids compared to the unsubstituted phenyl compound. See Table 4. Anticholinesterase A c t i v i t y The anticholinesterase a c t i v i t y of the oxadiazolones of t h i s report was measured using housefly heads as the enzyme source and the method of Ellman(3^ was u t i l i z e d to determine the enzyme activity. The conditions for the enzyme i n h i b i t i o n studies are shown below:


22.

SANBORN ET AL.


245

Anticholinesterase A c t i v i t y Conditions Enzyme Source: H o u s e f l y heads, E l e c t r i c e e l I n c u b a t i o n Time: 30 minutes Temperature: 30 C Enzyme A c t i v i t y : E l l m a n ' s Reagent pH: 8 I n T a b l e 5 a r e the molar 1^ values f o r oxadiazolones that d i f f e r o n l y i n t h e i r s u b s t i t u e n t s a t the 4 - p o s i t i o n of the d i h y d r o b e n z o f u r a n r i n g . The potency of these m o l e c u l e s i s i n the o r d e r CH > F> i-C«H >H>Cl. T h i s was n o t t h e o r d e r o f w h o l e i n s e c t t o x i c i t y , w h i c h was H> i-C.H >CH >F>Cl. S i n c e s t u d i e s were not performed w i t h s y n e r g i s t s , i t i s not p o s s i b l e t o c h a r a c t e r i z e the reasons the poor c o r r e l a t i o n between jLn v i t r o a n t i c h o l i n e s t e r a s e a c t i v i t y and whole i n s e c t t o x i c i t y . What i s c l e a r , from the s t u d i e s i s that_ two of the m o l e c u l e s , 4-CH ( 1 ^ 1 . 6 x 1 0 M) and 4-F d _ 4.4x10 M) r e p r e s e n t a p o t e n t new c l a s s o f a n t i c h o l i n e s t e r a s e agents u n l i k e the known organophosphates o r carbamates. T a b l e 6 c o n t a i n s d a t a t h a t show the e f f e c t s of methyl groups a t the 2 , 4 - p o s i t i o n s of the d i h y d r o b e n z o f u r a n y l r i n g on the a n t i c h o l i n e s t e r a s e potency of t h e s e m o l e c u l e s . C l e a r l y , f j o m an a n t i c h o l i n e s t e r a s e p e r s p e c t i v e , i t i s b e s t (1^^=1.6x10 M) t o have m e t h y l groups p r e s e n t i n the 2 and 4 p o s i t i o n s of the b e n z o f u r a n y l r i n g . The next b e s t arrangement of m e t h y l groups f o r a n t i c h o l i n e s t e r a s e a c t i v i t y i s t g have a m e t h y l group a t each of the 2 and 4 p o s i t i o n s ( I - «9.8x10 M) f o l l o w e d by the r a o l e c u l e w i t h a s i n g l e methyl group at the 2 - p o s i t i o n ( l = 1 . 7 x l 0 ~ M). 3

7


7

3

g

3

5 0

7

5 Q

From an a n t i c h o l i n e s t e r a s e / i n v i v o t o x i c i t y p o i n t of v i e w , t h e s e m o l e c u l e s a r e perhaps the most i n t e r e s t i n g . They a r e as e f f e c t i v e i n some cas_es ( 2 - F , I 2 . 1 x l 0 ~ M) as the b e s t 5-methoxy compound ( I 1.6x10 M), and y e t t h e i r whole i n s e c t t o x i c i t y on houseflies Is l e s s . Again, without studies i n c o r p o r a t i n g syner g i s t s i n t o the t o x i c i t y e v a l u a t i o n s , i t i s not p o s s i b l e t o d e t e r mine the reasons f o r the d i s c r e p a n c y between the 1^ v i t r o and i n vivo a c t i v i t y . See T a b l e 7. 5

5

T a b l e 5.

Q

Q

A n t i c h o l i n e s t e r a s e A c t i v i t y of 4 - S u b s t i t u t e d benzofuranyl Oxadiazolones

Dihydro-

CH 0 3

CH

3

Structure X

I

Η CH. i-C.H Cl F 3

7

7

5

0

(M xlO

)

25 1.6 15 183 4.4


246


T a b l e 6·

A n t i c h o l i n e s t e r a s e A c t i v i t y o f 2-and 4-Methyl Substituented Dihydrobenzofuranyl Oxadiazolones Ο

Structure


X

Y

H CH. H CH J

3

T a b l e 7.

Enzyme A c t i v i t y I c (M xlO ) n

H H CH. CH^

17 25 9.8 1.6

A n t i c h o l i n e s t e r a s e A c t i v i t y of Oxadiazolones 5-Phenoxy S u b s t i t u e n t

Containing

Enzyme A c t i v i t y 7 777 ι r\V ν I(M χ 10")

Structure

5

0

5.8 2.7 9.1 15

H 2-F 4-C1 3,4,5-CH

These m o l e c u l e s , w h i c h a r e a l s o i n a c t i v e on h o u s e f l i e s i n t h e p r i m a r y s c r e e n , have molar I _ v a l u e s w h i c h a r e 100-710,000 l e s s than t h a t o f t h e most potent m o l e c u l e s o f t h i s r e p o r t , perhaps i n d i c a t i n g t h a t a l e a v i n g group a t t h e 5 - p o s i t i o n on the o x a d i a z o l o n e r i n g i s r e q u i s i t e f o r t h e a c t i v e a n t i c h o l i n e s t e r a s e s . See T a b l e 8. Q

Nature of the m o l e c u l a r i t y of the i n t e r a c t i o n of o x i d i a z o l o n e s w i t h h o u s e f l y head a c e t y l c h o l i n e s t e r a s e

benzofuranyl

For d e t e r m i n a t i o n o f how these i n h i b i t o r s i n t e r a c t w i t h house f l y a c e t y l c h o l i n e s t e r a s e t h e method o f A l d r i d g e and D a v i d s o n ( 3 ) was employed. The l o g % r e s i d u a l a c t i v i t y i s p l o t t e d a g a i n s t (molar c o n c e n t r a t i o n ) ( i n c u b a t i o n t i m e ) . When s t r a i g h t l i n e r e s u l t s , i t i s i n t e r p r e t e d that the enzyme-inhibitor i n t e r a c t i o n i s governed by pseudo f i r s t o r d e r k i n e t i c s and i s a b i m o l e c u l a r r e a c t i o n . F o r the


22.

SANBORN ET AL.

T a b l e 8.


A n t i c h o l i n e s t e r a s e A c t i v i t y of 5-Alkyl or 5-Aryl Oxadiazolones ο

J


Structure R CH. C A Pn p - C l Ph 5

Ν

Enzyme A c t i v i t y I (Μ χ10 ) ϋ

5

0

110 3,000 710,000 5,800

molecule i n F i g u r e 1, Jjhe b i m o l e c u l a r r a t e c o n s t a n t was found t o be 5.9x10 l . m o l . m i n · The o b s e r v a t i o n t h a t these o x a d i a z o l o n e s r e a c t w i t h a c e t y l c h o l i n e s t e r a s e i n a b i m o l e c u l a r f a s h i o n puts them i n the same c a t e g o r y as t h e b e t t e r known organophosphate a c e t y l c h o l i n e s t e r a s e i n h i b i t o r s . W h i l e t h e r e a c t i v e c e n t e r i n an organo phosphate i n h i b i t o r s i s c h a r a c t e r i z e d , t h e m e c h a n i s t i c d e t a i l s o f how these o x a d i a z o l o n e s i n h i b i t t h i s enzyme a r e unknown and await further investigation. R e v e r s i b i l i t y o f t h e enzyme - i n h i b i t o r complex I t was o f i n t e r e s t t o determine t h e whether these oxadiazolones were i r r e v e r s i b l e i n h i b i t o r s l i k e many organophosphates o r r e v e r s i b l e i n h i b i t o r s l i k e carbamates. Since acetyl cholinesterase enzyme from E l e c t r o p h o r u s e l e c t r i c u s was more s t a b l e , i t was chosen as t h e enzyme f o r t h e s e r e g e n e r a t i o n s t u d i e s . T h e enzyme was i n h i b i t e d t o about 36% o f i t s a c t i v i t y , r e q u i r i n g 30 m i n . Then t h e t e s t s o l u t i o n was p l a c e d i n d i a l y s i s t u b i n g t o r e t a i n t h e enzyme and a l l o w i n h i b i t o r t o pass through i n t o t h e d i a l y s i s s o l u t i o n . Subsequently, a l i q u o t s were t a k e n from t h e t e s t s o l u t i o n t o measure i n c r e a s e i n a c t i v i t y r e s u l t i n g from d e c o m p o s i t i o n o f t h e enzymei n h i b i t o r complex. T h i s r e g e n e r a t i o n s t u d y was o n l y c a r r i e d o u t f o r seven hours as breakdown o f t h e enzyme became s i g n i f i c a n t . D u r i n g t h e seven hour experiment adequate c o n t r o l s ensured t h a t i n c r e a s e i n enzyme a c t i v i t y was due t o r e g e n e r a t i o n o f t h e enzyme. E x a m i n a t i o n o f F i g u r e 2, a l l o w s t h e c a l c u l a t i o n o f a ^ ~" g e n e r a t i o n o f a p p r o x i m a t e l y 43 h o u r s . o re

Conclusions T h i s r e p o r t b r i e f l y summarizes t h e s y n t h e s i s , i n s e c t t o x i c i t y and a n t i c h o l i n e s t e r a s e a c t i v i t y o f some n o v e l d i h y d r o b e n z o f u r a n y l o x a d i a z o l o n e s , a c l a s s o f i n s e c t i c i d e s whose major s t r e n g t h l i e s i n t h e i r t o x i c i t y t o aphids w i t h reduced a c t i v i t y on h o u s e f l i e s , twos p o t t e d s p i d e r m i t e s and c o r n earworms. T h i s i s s i m i l a r t o t h e p r e v i o u s l y r e p o r t e d RP 3 2 , 8 6 1 , w h i c h a l s o was most a c t i v e o n s u c k i n g i n s e c t s . The m o l e c u l e w i t h t h e broadest t o x i c i t y spectrum

American Chemical Society Library

1155 16th St., N.W. Washington, D.Cof20036 Baker et al.; Synthesis and Chemistry Agrochemicals ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

247

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

1. B i m o l e c u l a r r a t e

constant.


>

K w

8

o w

>

•< O

W

3

> z

55

Z

en

00

*>

22.

SANBORN ET AL.

Synthesis

and Activity

of Some Oxadiazolones

249


14-1 o

co •H U

cd

u

ca)CD 60 0)

o a)

II N

c a) C •H

a

c

N

a) a H

0)

oo cu •H x


250


contained the 2,2-dimethyl dihydrobenzofuranyl ring system. The most toxic molecule to aphids had an additional methyl in the 4 position of the dihydrobenzofuranyl ring. Enzyme inhibition studies with housefly acetyl cholinesterase demonstrated that these molécules^ were potent anticholinesterases (30 min Ι,-Q values 1-10x10 M for the most active molecules). However, the cor relation between their in vitro enzyme inhibitory potency and their in vitro activity on houseflies was poor, indicating the importance of other factors that determine whole insect toxicity of these molecules. Further work must be carried out to determine the exact nature of the mechanism by which these molecules inhibit acetyl cholinesterase· Downloaded by UNIV LAVAL on May 9, 2016 | http://pubs.acs.org Publication Date: November 3, 1987 | doi: 10.1021/bk-1987-0355.ch022

Literature Cited 1. Ambrosi, D.; Bic, G.; Desmoras, J.; Gallinell, G; Roussel, G. Proc Br. Crop Prot. Conf. Pests. Dis. 1979, (2) 533. 2. Pilgram, K. H., Skiles, R. D. U. S. Patent 4 406 910, 1983. 3. Ellman, G. L., Courtney, K. D., Andres, V., Jr., Feather stone, R.M. Biochemical J. 1961, 7, 62-70. 4. Aldridge, W. Ν., Davison, A.N. Biochem. J . , 1952, 51, 62-70. RECEIVED August 5, 1987


Synthesis, Insecticidal Activity, and Anticholinesterase Activity of Some

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