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~ ) P e rg am on TetrahedronLetters,Vol. 38, No. 10, pp. 1741-1744, 1997O 199 7 Elsevier Science I.,tdAll rightsreserved.Printed n G reat Britain.0040-4039/97 $17.00 + 0 .00PII: S0040--4039(97)00205--0

R H O D I U M ( H ) ( S ) . N . ( A R Y L S U L F O N Y L ) P R O L I N A T E C A T A L Y Z E DA S Y M M E T R I C I N S E R T I O N S O F V I N Y L - A N D P H E N Y L C A R B E N O I D S I N T O

T H E S i - H B O N DH u w M . L . D a v i e s ,* a T o r e H a n s e n , a J a m e s R u t b e r g ,b and Pau l R . Bruz insk i a

a) Depar tm en t o f Chem is t ry , S ta te Un ivers i ty o f New Yo rk a t Buffa lo , Buffa lo , NY 14260-3000b ) D e p a r t m e n t o f C h e m i s tr y , W a k e F o r e s t U n i v e rs i ty , B o x 7 4 8 6 , W i n s t o n - S a l e m , N C 2 7 1 0 9

Abstract: Allylsilanes or benzylsilanes of high enantiomeric purity (77-95% ee) are form ed fromthe rhod ium (lI) (S)-N-[p-(dodecylphenyl)sulfonyl]prolinate (1) catalyzed decomposition ofvinyldiazomethanes or phenyM iazomethanes in the presence o f dimethylphenylsilane (3). 1997 Elsevier Science Ltd. A ll fights reserved.

A l l y l s i l a n e s a r e v e r s a t i l e i n t e r m e d i a t e s i n o r g a n i c s y n t h e s i s s i n c e t h e y c a n b e u s e d i n a v a r i e t y o fs te reose lec t ive t rans fo rmat ions .1 An a t t rac t ive app roach fo r the fo rmat ion o f a l ly l s i l anes i s the S i -H in ser t ion o fv i n y l c a r b e n o i d s i n t o t r ia l k y l s il a n e s . L a n d a i s a n d c o - w o r k e r s h a v e r e p o r t e d t h a t r a c e m i c a l l y l s i la n e s o f d e f i n e da l k e n e g e o m e t r i e s m a y b e r e a d i l y f o r m e d t h r o u g h r h o d i u m ( I I ) a c e t a t e c a t a l y z e d d e c o m p o s i t i o n o fv i n y l d i a z o m e t h a n e s i n t h e p r e s e n c e o f t r i a l k y l s i l a n e s . F u r t h e r m o r e , b y u s in g ( R ) - p a n t o l a c t o n e a s a c h i r a la u x i l i a r y o n t h e v i n y l d i a z o m e t h a n e , i t w a s p o s s i b l e t o p r o d u c e t h e a l l y l s i l a n e s i n 3 2 - 7 0 % d e . 3 R e c e n t l y , a na l t e r n a t i v e a p p r o a c h f o r a s y m m e t r i c i n s e r t io n i n t o th e S i - H b o n d w a s d e s c r i b e d u s in g a s e r i e s o f c h i r a lr h o d i u m ( I I) c a r b o x y l a t e s a n d c a r b o x a m i d e s .4 U s i n g p h e n y l d i a z o m e t h a n e a s s u b s tr a t e , S i - H i n s e r t i o n s w e r ea c h i e v e d i n 7 - 4 7 % e e . 4 A b s e n t f ro m t h e c a t a l y s t s s u r v e y e d w e r e r h o d i u m ( I I ) ( S ) - N - ( p -a lky lpheny l )su l fony lp ro l ina teswh ich have been shown to be exce l l en t ca ta ly s t s fo r asymm et r ic cyc lop rop ana t ionsb y v i n y lc a r b e n o i d s a n d p h e n y l c a r b e n o i d s6 (up to 98% ee) . In th i s paper , we descr ibe tha t rhod iu m(l l ) (S ) -N-[p -( d o d e e y l p h e n y l ) s u l f o n y l ] p r o l i n a t e ( 1 ) 5 is a v e r y e f f e c t i v e c a t a l y s t f o r a s y m m e t r i c S i - H i n s e r t i o n r e a c t i o n s ,l ead ing to benzy ls i l ane s and a l ly l s i l anes in 77 -95% ee (eq 1 ).

, N O 1 ~ . . , 1SO2Ar J4 R1 R2CO 2M e Ar = p-.C12H2506H4 CO 2M epen tane , -78 C [ 77-95% e e I

(1 )

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T he u t i l i ty o f t he r hod i um p r o l i na t e c a ta l y s t 1 f o r a s ymm e t r i c S i - H i n s e r t ions w a s i n i t i a l l y de t e r mi ne dus i ng t he s t a nda r d r e a c t ion c ond i t i ons t hat w e r e r e c e n tl y r e po r te d by D oy l e a nd M oody . 4 R hod i um( I D p r o l i na te 1c a t a l y z e d d e c o m p o s i t i o n o f m e t h y l p h e n y l d i a z o a c e t a t e ( 2 ) i n t h e p r e s e n c e o f d i m e t h y l p h e n y l s i l a n e ( 3 ) ind i c h l o r ome t ha ne a t r oom t e mpe r a t u r e r es u l te d i n t he f o r ma t i on o f t he i n s e r t ion p r oduc t 44 i n a ve r y d i s a ppo i n t i ng3% e e . I t i s w e l l e s t a b li s he d , how e ve r , t ha t phe ny l c a r be no i d a nd v i ny l c a r be no i d c yc l op r opa n a t i ons c a t a l yz e d byr hod i um p r o l i na t e s p r oc e e d i n m uc h h i ghe r l e ve l s o f a s ym me t r i c induc t i on w he n hyd r oc a r bon s o l ve n t s a r e u s edi ns t e a d o f d i c h l o rome t ha ne . A s i mi l a r l y d r a ma t i c e ff e c t w a s s e e n i n t he s e a s ym me t r i c S i - H i n s e r t i on r ea c t i ons .R e pe a t i ng t he r e a c t i on f o r t he de c om pos i t i on o f 2 by t he r hod i um c a t a l y s t 1 u s ing pe n t a ne a s s o l ve n t a t r oomt e mpe r a t u re r e s u l t e d i n t he f o r m a t i on o f 4 i n 36% e e . F u r t he r impr ove m e n t i n e na n t i o s e le c t i v i ty w a s p os s i b l e byc onduc t i ng t he r e a c t ion a t l ow e r t e mpe r a tu r e s ; a t -78 C , 4 w a s f o r m e d i n 85% e e . T he a bs o l u t e s te r e oc he mi s t r yo f 4 w a s de t e r mi ne d t o be R b y c onve r s i on o f 4 t o ( R ) - ( + ) - 1 - phe ny l - 1 , 2 - e t ha ne d i o l by t he p r oc e d u r e de ve l op e dby L a nda i s .3

,N o 1 , ,P h S O s A r J 4N 2 : m ( + M o a P h S i -H = M e 2 P h S i ,,,..~Ph2 C O 2 M o 3 A r = P -C la H a5 C sH 4 4 C O 2 M oentry ternp

1 252 253 04 -78

s o l ve n t y i e l d , % a e e , % b ( a bs . c on f i s . )CH2C12 63 -3 (S)pentane 65 36 (R)pentane 52 51 (R)pentane 50 85 (R)

a : I so la ted y ie ld a f t e r d i s ti l l a tion , b : Enan t iomer ic excesses (ee ' s ) de te rm ined by HP LC (Chi race l OD colum n, 5%2- p r opa no l : 95% he xa ne )

T he c a t a l y t i c a s ym me t r i c S i - H i n s e r t i on c a n be e x t e nde d t o p r e pa r e a s e r i e s o f a l l y l s i l a ne s a s s how n i nT a b l e 1 . R hod i um( I I ) p r o l i na te I c a t a l yz e d de c om pos i t i on o f t he v i ny l d i a z ome t ha ne s 5 a t - 78 C r e s u l t e d i n theform at ion of the a l ly l s i l anes 6 in 77-95% ee . The e nant iom er ic pur i ty of the a l ly l s il anes 6 wa s read i ly de te rm inedby t he u s e o f c h i r a l sh i f t r e a ge n t s . T he a bs o l u t e st e r e oc be rn i s tr y o f 6a w a s d e t e r mi ne d t o be R b y c onv e r s i on o f6a t o ( R ) - ( + ) - 4 - phe n y l - l , 2 - bu t a ne d i o l by t he s t a nda r d p r oc e du r e de ve l op e d by L a nda i s .3 T he r e f o r e , i t a ppe a r st ha t 1 r e su l t s i n t he oppo s i t e a s ymme t r i c i nduc t i on to t ha t obs e r ve d w h e n ( R ) - pa n t o l a c tone w a s u s e d a s a c h i r a lauxi l i a ry , a t rend tha t w as a l so seen in the asy mm et r i c cyc lopropanat ions .5C , 7 The y ie lds of 6 were de te rm ined byN M R i n t e g r a t ion u s i ng 1 , 4 - d i me t hoxybe nz e ne a s a n i n t e r na l s t a nda r d , s i nc e 6 unde r w e n t p a r t i a l de c om pos i t i onon a t t e mp t e d pu r i f i c a t i on by d i s t i ll a t i on o r c h r om a t og r a phy . E ve n t hough t he s e a l l y l s i l a ne s ma y no t be r e a d i l ypur i f i ed , i t has a l rea dy been sho wn tha t the racemic a l ly l s i l anes can be e f fec t ive ly used in fur ther s t e re ose lec t ivet rans format ions .2a ,3 T he enan t iose lec t iv i ty n these S i -H insert ions i s much h igher than the va lues obta ined us ing(R)-pantolac tone as a s to ichiomeWic chi ra l auxi l i a ry on the v inylcarbenoid ,3 the a l t e rna t ive metho d fo r asym met r i cvinylcarbe noid t rans format ions .7

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Tab le 1. Rh odiu m(ll ) prolinate 1 catalyzed decomp osition of vinyldiazomethanes $ in the presence of 3.

su b s t r a t e product yield , %a ee, %b (abs. conflg.)PhN 2 : = : ~ 5 aCO2MeCH3

N 2 ~ ~ / 5 bC02Me/P h

N 2 ~ / ~ 5 cCO2Me

N2==~ 5dCO2Me

5 eN2=~,CO2Me

PhMe2PhS ,, , .. ~ /CO2Me

6 a 3

Me2PhS , , , . . ~ CH3CO2Me 6 b

__/PhMe2PhS , , , . .~ / -C02Me

Me2PhSi ,...~CO2Me

Me2PhSi , , . . ~CO2Me

76

6 4

91 ( R ) c

9 5 ( f ~ ) d

6 C 3

6 d

6 e

6 8

63

77

77 (R)d

85 ( ~

92 (R)

a : Yie ld de te rm ined us ing 1 ,4-dime thoxyb enzene as an in te rna l s tandard , b : Enant iom er ic excesses (ee ' s )determined by I H NM R using praseod ym ium(l] /) tr is[3-(heptafluoropropylhydroxyrnethylene)-(-)-camphorate] asa c h i r al sh i f t r ea ge n t, c : Ass igne d by c onve r s ion o f 6a to ( R ) - ( + ) - 4 - phe n y l - l , 2 - bu ta ne d io l . 3 d : Te n ta t ive lyassigned on th e assum ption that the asymm etric induction parallels tha t for the formation of 4 and 6a.

In summ ary, the rhodium(H) prolinate com plex 1 was show n to be an excellent catalyst for the asym metricsynthes is of benz yl- and a l ly lsi lanes. These s tudies demon stra ted once aga in the remarkable e f fec t tha t a non-pola r so lvent has on the extent of asymm etr ic induc t ion when us ing 1 as the ca ta lys t . Fur thermore , the h ighsolubi l i ty of 1 in hy drocarb on solvents enables the S i-H inser tions to be ca r r ied out a t low temperatures , wh ichresults in further impro vem ent of the asym me tric induction. Som e of the racemic allylsilanes have already beenexploited for further stereoselective transformations, 3 and the availabili ty of these com pou nds in enantioen richedfo rm will greatly e xpa nd their syn thetic utility. 8Acknowledgement: F ina nc ia l suppor t o f t h is wor k by the Na t iona l S c ienc e F ounda t ion ( C H E 94216 49) i sgratefully acknowledged.

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1 7 4 4

R e f e r e n c e s a nd N o t e s1 . ( a ) San t e l l i , M . ; Pons , J . -M. In Lewis Ac ids and Se lec t iv i ty in Organic Synthes is ; C R C P r e s s : B o c a

R a t o n , N e w Y o r k , 1 9 96 ; p p 9 1 -2 6 3 . ( b ) M a s s e , C . E . ; P a n e k , J . S . Chem. Rev . 1 9 9 5 , 9 5 , 1293. (c)Panck , J . S . I n C o m p r e h e n s i v e O r g a n ic S y n th e s i s , T r o s t , B . M . E d . , P e r g a m o n P r e s s : O x f o r d , N e wYork , 1991 ; Vo l . 5 , pp 580 -628 .

2 _ F o r e a r l ie r e x a m p l e s o f r h o d i u m c a r b e n o id in s e r ti o n s i n to S i -H b on d s , s e e : ( a ) B a g h e r i , V . B . ; D o y l e , M .P . ; T a u n t o n , J . ; C l a x t o n , E. E. J . Org. Che m. 1 9 8 8 , 5 3 , 6 1 5 8 . ( b ) A n d r e y , O . ; L a n d a i , Y . ;P l anchenau l t , D . Tetrahedron Lett . 1993, 34 , 2977 . ( c ) Land ai s , Y .; P l anchena u l t , D . Te trahedron Le tt .1 9 9 4 , 3 5 , 9 5 4 9 . ( d ) A n d r e y , O . ; L a n d a i s , Y . ; P l a n c h e n a u l t , D . ; W e b e r , V . T e t r a h e d r o n 1 9 9 5 , 5 1 ,12083.

3 . Lan dai s , Y . ; P l anchenau l t , D . ; W eber , V . Tetrahedron Lett. 1994, 3 5, 9549.4 . B u c k , R . T . ; D o y l e , M . P .; D r y s d a l e , M . J. ; F e r r i s , L . ; F o r b e s , D . C . ; H a i g h , D . ; M o o d y , C . J . ;

P e a r s o n , N . D . ; Z h o u , Q . - L . Te trahedron Le tt . 1996, 3 7 , 7 6 3 1 .5 . ( a ) D a v i e s , H . M . L . ; H u t c h e s o n , D . K . T e t r a h e d r o n L e t t . 1 9 9 3 , 3 4 , 7 2 4 3 . ( b ) D a v i e s , H . M . L . ;

P e n g , Z . - Q . ; H o u s e r , J. H . Te trahedron Le t t . 1 9 9 4 , 3 5, 8939 . ( c ) Da v i es , H . M. L . ; B ruz i nsk i , P . R . ;L a k e , D . H . ; K o n g , N . ; F a l l , M. J . J . Am. Chem. Soc. 1 9 9 6 , 1 1 8 , 6 8 9 7 . ( d ) D a v i e s , H . M . L . ; D o a n ,B. D . Te trahedron Le tt . 1996 , 3 7, 3967.

6 . ( a ) D av i es , H . M . L . ; B rnz i nsk i , P . R . ; Fa l l , M. J . Tetrahedron Lett . 1 9 9 6 , 37, 4 1 3 3 . ( b ) D o y l e , M . P . ;Z h o u , Q . - L . ; C h a r n s a n g a v e j , C . ; L o n g o r i a , M . A . ; M c K e r v e y , M . A . ; G a r c i a , C . F . Te trahedro n Le t t.1 9 9 6 , 3 7, 4 1 2 9 .

7 . D a v i e s , H . M . L . ; H u b y , N . J . S . ; C a n t r e l l , W . R . ; J r ., O l i v e , J. L . J . Am. Chem. Soc. 1 9 9 3 , 1 1 5 ,9 4 6 8 .

8 . F o r a n a l t e rn a t i v e s t r a te g y f o r c a t a l y ti c a s y m m e t r i c S i - H i n s e rt i on s o f v i n y l d i a z o m e t h a n e s u s in g R h 2 ( S -M EPY )4 as ca t a l y s t (up to 72% ee) , see : Bu l ugaha p i t iya , P . ; Landai s , Y . ; Par r a -R apad o , L . ; P l anchenau l t ,D . ; W e b e r , V. J . Org. Chem. 1997 , i n p ress .

(Received in USA 25 N o v e m b e r 1996; accepted 27 January 1997)