Unexpected Tethering in the Synthesis of Methyl-Substituted Acetyl-1-oxaspiro[4.5]decanes: Novel Woody–Ambery Odorants with Improved Bioavailability
作者:Philip Kraft、Kasim Popaj
DOI:10.1002/ejoc.200700833
日期:2008.1
spirocyclic analogs of Iso Gamma (3) with improved water solubility and bioavailability, it was envisaged to spiroannulate 1-acetyl-1,2-dimethylcyclohexanone at the 4-position with a 3,3-dimethyltetrahydrofuran-2-yl moiety that would mimic the polarity of the double bond by its ether function. 3,3-Dimethyl-4-methylenehex-5-en-1-ol (9) was prepared by copper(I)-mediated 1,4-conjugate addition of the Grignard
为了研究具有改善的水溶性和生物利用度的 Iso Gamma (3) 的螺环类似物的嗅觉特性,设想在 4-位用 3,3-二甲基四氢呋喃-2-螺环化 1-乙酰基-1,2-二甲基环己酮yl 部分将通过其醚功能模拟双键的极性。3,3-Dimethyl-4-methylenehex-5-en-1-ol (9) 是通过铜 (I) 介导的 1,4-共轭加成将氯丁二烯 (7) 的格氏试剂加入 3-methylbut-2 制备的-enal 与随后的 LAH 减少。然而,在 Me2AlCl 存在下,二烯 9 与 (E)-3-methylpent-3-en-2-one 的 Diels-Alder 反应出人意料地仅提供了不需要的间位加合物 10,如在用 MeSO3H 环化为 11 后发现的。错误的选择性是由于路易斯酸的束缚作用,这可以通过将亲二烯体的羰基功能改变为羟基来避免。从而 (5'R*,7'S*,8'S*)-构型的