1,6-Asymmetric Induction Utilizing Asymmetric Desymmetrization by Diastereoselective C-O Bond Fission of the 4-Substituted Bicyclic Acetal: Application to a Synthesis of (-)-Frontalin.
作者:Naoyoshi MAEZAKI、Takeshi SHOGAKI、Masashi UCHIDA、Katsuya TOKUNO、Tsuneaki IMAMURA、Tetsuaki TANAKA、Chuzo IWATA
DOI:10.1248/cpb.46.217
日期:——
1, 6-Asymmetric induction was achieved in the acid-induced diastereoselective acetal cleavage reaction of a 4-substituted bicyclic acetal 8 bearing a chiral sulfinyl group. On treatment with titanium tetrachloride and 2, 6-disubstituted pyridine bases, 8 gave a synthetically versatile 3, 3-disubstituted dihydropyran derivative 9a with moderate diastereoselectivity. The utility of this chiral synthon was successfully demonstrated by a formal synthesis of (-)-frontalin.
1, 6-不对称诱导在一种酸诱导的非对映选择性氨基醛顶部裂解反应中得以实现,该反应涉及一种带有手性亚磺酰基的4取代双环氮杂环醛8。在与氯化钛和2, 6-双取代吡idine碱的处理下,8生成了合成多用途的3, 3-双取代二氢吡喃衍生物9a,具有适度的非对映选择性。这一手性合成前体的有效利用通过(-)-frontalin的形式合成成功证明。