Pp. Deshpande et al., A CONCISE, ENANTIOSELECTIVE SYNTHESIS OF (-)-HONGCONIN AND (-HONGCONIN()), Journal of organic chemistry, 61(2), 1996, pp. 455-458
Optically pure enone 9c, available in three steps from known 6-deoxy D
-galactal derivative 7b, reacts with cyanophthalide 6 to directly affo
rd the natural product (-)-hongconin (1), a compound from traditional
Chinese medicine recently shown to exhibit antianginal activity. The e
nantiomer of 1 and its (+)-cis-diastereomer were also synthesized in a
parallel fashion from the L-sugar counterpart. The use of C-glycoside
Michael accepters, as opposed to their O-glycoside counterparts, repr
esents a potentially useful simplification of phthalide annulation met
hodology in synthesizing numerous other such optically pure isochroman
quinoids, since it obviates the inconvenience of additional steps late
in the synthetic scheme associated with reductive manipulation of a r
emaining acetal moiety into the desired pyran ring substituent.