REGIO- AND STEREOSELECTIVE CONJUGATE ADDITION OF NITROGEN NUCLEOPHILES TO 2-ALKENYL N-METHYLTHIAZOLIUM IODIDES. SYNTHESIS OF D-3-EPI-DAUNOSAMINE AND SOME LINCOSAMINE ANALOGUES

Article abstract of DOI:10.1016/S0040-4020(01)87939-4

A two-carbon homologation-amination technology of aldehydes is described.Key steps involve the Michael-type addition of a nitrogen nucleophile (benzylamine, trimethylsilylazide, potassium phthalimide) to a 2-alkenyl N-methylthiazolium salt obtained by olefination of the aldehyde with the phosphorane (1), and the thiazole-to-formyl deblocking.The addition of benzylamine to the thiazolium salt derived from the acetonide of D-glyceraldehyde occurs with a good level of syn-diastereoselectivity (ds, 85-90percent) in agreement with a modified Felkin-Anh model.This technology is employed in short synthetic routes to D-3-epi-daunosamine from 4-deoxy D-threose and some lincosamine analogues from α-D-dialdogalactopyranose.