An Enantioselective Total Synthesis of Natural (+)-Luciduline
作者:Wolfgang Oppolzer、Martin Petrzilka
DOI:10.1002/hlca.19780610802
日期:1978.12.13
The naturally occurring Lycopodium alkaloid (+)-luciduline (1) has been synthesized from (R)-5-methyl-cyclohex-2-en-1-one (12) by a sequence of seven steps (s. Scheme 6) in 33% overall yield. The key step 46 presumably involves a transient nitrone 5 which undergoes a highly regioselective intramolecular addition to a non-polarized olefinic bond.
The Diels-Alder reaction of 5-methyl-2-cyclohexene-1-one (I) with butadiene was examined. It was concluded that addition of butadiene to the dienophile (I) took place from the opposite side to a secondary methyl side to give initially the cis adduct (IIb), which then epimerizes mostly to the trans derivative (IIa).