A short and practical entry to optically pure 5a-carbahexopyranose and 1-thio-5a-carbahexopyranose representatives is described. Besides a few functional group and protecting group manipulations, the synthetic scheme counts on two fundamental carbon−carbon bond-forming reactions, namely (i) a regio- and stereoselective aldol addition between heterocyclic (silyloxy)diene donors (6 or 13) and D-glyceraldehyde as the acceptor (7) and (ii) a chemo- and stereoselective silylative cycloaldolization involving bifunctional aldehydes (10, 16, and 21). The 1H NMR based configurational and conformational assignment of target structures 1−5 and bicyclic intermediates 11, 12, 17, 18, and 22 is discussed. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)