DIASTEREOSELECTIVE SYNTHESIS OF C-GLYCOSYLNORBORNENONES

Thermal reaction of (E)-3,4,5,6,7-penra-O-aceryl-1,2-dideoxy (la)and-D -manno-hept-1-enitol (1b) with 2-methyl-3,4-diaryl-5-phenylcyclopentad ienones (2a-c) afforded diastereoselectively thyl-2,3-diruyl-4-phenyl- (5S,6R)-5-exo-(D-galacto- (3a-c) and -exo-(D-manno-penta-O-acetylpenti tol-1-yl)-6-endo- nitrobicyclo[2.2.1]hept-2-en-7-ones (6a-c) and varia ble amounts of the 1-phenyl-4-methyl regioisomers 4a-e and 7a-c, depen ding upon the p-subsrituent in the aryl moiety. 1-C-Arylalditols 5, 8- 9 are also obtained in refluxing xylene.