Selective functionalization of silyl-N-Cbz-1,3-thiazolidines with aldehydes to homologated α-hydroxy thiazolidines and fused oxazolidinones

N-Cbz-2-trimethylsilyl-1,3-thiazolidine can be easily functionalized under fluoride ion conditions with aldehydes as electrophiles. The reaction selectively affords new cyclo-fused oxazolidinones or homologated α-hydroxy thiazolidines depending on the temperature of the reaction and the nature of the aldehyde.