This method avoided the formation of disulfanilated product in the first step and conducted to the product (8) in 65% yield and 59% of diastereomeric excess, calculated from the integration of the [sup.1]H-NMR signals corresponding to methylsulfinyl group in 2.88 and 2.59 ppm.
After purification, the 2-methylsulfanyl-2methylsulfinyl-1-indanone was obtained in 84% yield and 73% of diastereomeric excess. The majority diastereoisomer was isolated by TLC in 55 % yield.
In this case, the obtained yield was 93% and 73% of diastereomeric excess. It is noteworthy that the majority diastereoisomer formed was the same in the case of the reaction catalyzed by TEBAC.
The yields obtained were 93% and 90% diastereomeric excess.
The reduction of S,S-2-methylsulfanyl-2methylsulfinyl-1-indanone (diastereoisomer mixture 10:0.8) using NaB[H.sub.4] was performed in metanol as solvent, isolating a unique diastereoisomer (10) in 70% yield and 90% of diastereomeric excess (Scheme 5).