Stereoselective hydrostannation: synthesis and absolute configuration of (-)-menthyl 2,3-diphenyl-3-(trimethylstannyl) propanoates and derivatives

Article abstract of DOI:10.1016/0022-328X(92)83365-O

Free radical hydrostannation of (-)-menthyl (E)-2,3-diphenylpropenoate (1) leads to a mixture of four adducts: two threo diastereoisomers (approx. 90percent) and two erythro diastereoisomers (approx. 10percent).Whereas threo diastereoisomers 2 (38percent) and 3 (51.2percent) could be isolated by column chromatography and fractional recrystallization, erythro diastereoisomers 4 and 4' (6.5percent and 4.3percent) could not be separated.Bromodestannylation of 2 and 3 yielded two diastereoisomers in each case, 9-10 and 11-12 respectively, which were isolated and characterized by spectroscopic methods.The reduction of bromo esters 9-12 with lithium aluminium hydride gave (R)-(-)- and (S)-(+)-2,3-diphenyl propanols 13 and 14 of known abolute configuration.Working back from the stereochemistry of 13 and 14 and taking into account the NMR data, the stereochemistry of their precursors was assigned.Full 1H, 13C, and 119Sn NMR data are given.