TOTAL SYNTHESIS OF VERTICILLENE - A BIOMIMETIC APPROACH TO THE TAXANE FAMILY OF ALKALOIDS

Intramolecular reductive coupling of the bis-aldehyde (10) in the presence of Ti(O), followed by 1,4-reducdon of the resulting tetraene (9) using sodium in ammonia, provides a facile synthesis of E,E-verticillene (8), the putative biogenetic precursor of the taxane family of alkaloids e.g. (1) and (2). Treatment of either verticillene (8), verticillene 7,8-epoxide (21), verticillol 7,8-epoxide (27) or anhydroverticillol 7,8-epoxide (29) with Lewis acids fails to produce the corresponding taxane carbon framework, viz (3), and instead only products e.g. (23), (24) and (31) resulting from rearrangements of the epoxide rings in the substrates are obtained. © 1990.