Synthesis of a C-linked hyaluronic acid disaccharide mimetic.

The synthesis of a C-disaccharide that is designed as a mimetic for the repeating unit disaccharide of hyaluronic acid is described. The target compound was obtained via the SmI2-promoted coupling reaction of the sulfone, 2-acetamido-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-1,2-dideoxy-1-pyridinylsulfonyl-beta-D-glucopyranose (6), and the aldehyde, p-methoxyphenyl 2,3-di-O-benzyl-4-deoxy-4-C-formyl-6-O-p-methoxybenzyl-beta-D-glucopyranoside (14).

A Concise, Enantioselective Synthesis of (-)- and (+)-Hongconin.

Optically pure enone 9c, available in three steps from known 6-deoxy D-galactal derivative 7b, reacts with cyanophthalide 6 to directly afford the natural product (-)-hongconin (1), a compound from traditional Chinese medicine recently shown to exhibit antianginal activity. The enantiomer of 1 and its (+)-cis-diastereomer were also synthesized in a parallel fashion from the L-sugar counterpart. The use of C-glycoside Michael acceptors, as opposed to their O-glycoside counterparts, represents a potentially useful simplification of phthalide annulation methodology in synthesizing numerous other such optically pure isochromanquinoids, since it obviates the inconvenience of additional steps late in the synthetic scheme associated with reductive manipulation of a remaining acetal moiety into the desired pyran ring substituent.