An efficient entry to the tetrahydropyran/cyclohexane moiety of tetronasin has been developed. An aldol reaction between a cyclohexanecarboxaldehyde, 8, and a (tetrahydropyranyl)acetate, 9, under controlled conditions followed by dehydration of the adduct 10 afforded predominantly (E)-ester 11, which on photoisomerization and subsequent reduction with iso-Bu2AlH provided the B/C ring system 13.
已开发出一种有效进入
四氢吡喃/
环己烷部分的方法。在受控条件下,
环己烷甲醛(8)与(
四氢吡喃基)
乙酸酯(9)发生醛缩反应,随后脱去加合物(10)中的
水分,主要得到(E)-酯(11),后者经光异构化并随后与异丁基二铝氢还原,得到B/C环系统(13)。