R - -Phenyl p-Toluenesulfinyl acetate

General Discussion. Aldol-type condensation of the magnesium enolate of (R)-(+)-phenyl (p-toluenesulfinyl)acetate, prepared with f-butylmagnesium bromide, with the aldehyde precursor of maytansine afforded, after desulfurization with Aluminum Amalgam, the desired 4,5-unsaturated 3-(5)-hydroxy ester in high yield and high diastereoselectivity (eq 3).  

Guy Solladie Fran oise Colobert University Louis Pasteur, Strasbourg, France 

Form Supplied in 0.5 M solution in THF. (7 )-Alpine-Borane is prepared from (+)-a-pinene, and (S)-Alpine-Borane from (—)-a-pinene. High purity a-pinene is available commercially. 

Preparative Methods readily prepared by hydroboration of either (+)- or (—(-a-pinene with 9-Borabicyclo[3.3.1]nonane (9-BBN) (eq 1). 

Since the neat reagent is most effective, the solvent is usually removed before reduction of the ketone. Brown has reported a synthesis using neat a-pinene and solid 9-BBN. The deuterium- or tritium-labeled compound may be prepared by hydroboration with labeled 9-BBN. Alternatively B-methoxy-9-BBN may be reduced with LiAlD4 (see Lithium Aluminum Hydride) in the presence of a-pinene.  

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Related Reagents. (R)-(+)-r-Butyl 2-(p-Tolylsulfinyl)-propionate (R)-(+)-Methyl p-Tolyl Sulfoxide (R)-(+)-Phenyl (p-Toluenesulfinyl)acetate. 

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