METHYLENECYCLOHEXANE ANNULATION. TOTAL SYNTHESIS OF (+/-)-AXAMIDE-1, (+/-)-AXISONITRILE-1, AND THE CORRESPONDING C-10 EPIMERS

Article abstract of DOI:10.1016/S0040-4020(01)87734-6

Conjugate addition of 2-(5-chloro-1-pentenyl)magnesium bromide (12) to 2-methyl-2-cyclopenten-1-one (6), followed by intramolecular alkylation of the resultant product, afforded (85percent) the bicyclic ketone 7, which was transformed (77percent) into the enone 16.Titanium tetrachloride-catalyzed conjugate addition of 3-methyl-1,1-bis(trimethylsiloxy)-1-butene to 16 gave (93percent) a 3:2 mixture of the keto acids 20 and 21, which were separated.Compound 20, the stereochemistry of wich was confirmed by a single-crystal X-ray analysis, was converted into (+/-)-axamide-1 (1) and (+/-)-axisonitrile-1 (2), while 21 was transformed into the corresponding C-10 epimers 8 and 9, respectively.