2aβ,3,4,6,7,8,8aβ,8bβ-八氢-3α,6,6,8bβ四甲基-2氢-萘[1,8-be]骈呋喃硼氢化反应的立体化学

Stereochemistry of Hydroboration of 2aβ, 3, 4, 6, 7, 8, 8aβ, 8bβ-Octahydro-3α, 6, 6, 8bβ Tetramethyl-2H-Naphtho [1, 8-bc] furan

<正> 化合物(2)和(3)经分子间和分子内的Diels-Alder反应是合成六氢萘和六氢(或八氢)萘骈呋喃的有效方法,如2与丁炔1,4二酸甲酯反应得4,而3a和3b的分子内Diels-Alder反应分别得5和6。这些化合物都是合成具有高度生物活性物质如ugand-ensidial(7)和forskolin(8)的重要中间体。但这些产物中均含AB反式结构和6β羟基官能团,因此研究如何把△~5转化为5αH.

Hydroboration of the title compound (1) gave two isomers in the ratio of 5.5:94.5, the minor alcohol was 5βH, 6βOH compound (11), while the major one was 5αH,6αOH compound (12). The assignment of stereochemistry has been supported by chemicaltransformation and ~1H NMR study.