DIALLYL SULFIDE COMPLEXES OF CHIRAL IRON AND RUTHENIUM LEWIS-ACIDS - YLIDE GENERATION AND DIASTEREOSELECTIVE [2,3]SIGMATROPIC REARRANGEMENTS TO GIVE THIOLATE COMPLEXES WITH NEW CARBON STEREOCENTERS

Reactions of the racemic iron diallyl sulfide complex )-C5H5)Fe(CO)(PP h(3))(S(CH2-CH=CH2)(2))](BF4-)-B-+ and t-BuOK (CH2Cl2 or THF, -80 to - 60 degrees C) give the thiolate complex (eta(5)-C5H5)Fe(CO)(PPh(3))(SC H(CH=CH2)CH2CH=CH2) (65-92%) as 77-68:23-32 mixtures of SS,RR/SR,RS Fe ,SC diastereomers. Reactions of the enantiomerically pure ruthenium di allyl sulfide complexes H5)Ru(S,S-chiraphos)(S(CH(2)CR=CH2)(2))](PF6-) -P-+ (5(+)PF(6)(-); R = a, H; R = b, CH3) and t-BuOK(CH2Cl2, -98 degre es C) give the thiolate complexes (5)-C5H5)Ru(S,S-chiraphos)(SCH(CR=CH 2)CH(2)CR=CH2) as 78:22 (8a, > 99%) and 87:13 (8b, 97%) mixtures of ch romatographically separable SSS/SSR PC,P'C',SC diastereomers. These tr ansformations likely involve intermediate sulfur ylides as described i n the title. Reactions of 8a,b with CH3I or PhCH(2)I and then NaI (ace tone, reflux) give, via cationic methyl or benzyl sulfide complexes, e nantiomerically enriched R'SCH(CH(2)CR=CH2)CR=CH2 (R/R' = H/CH3, 75%; CH3/CH3, 71%; H/PhCH(2) and CH3/PhCH(2), >99%) and (eta(5)-C5H5)Ru(S,S -chiraphos)(I) (6, greater than or equal to 97%). Complex 6 is readily recycled to enantiomerically pure 5a,b(+)PF(6)(-) (NH4+PF6-, CH3OH, S (CH(2)CR=CH2)2; 94-97%).