On the Stereoselectivity of γ-Lactol Substitutions with Allyl- and Propargylsilanes − Synthesis of Disubstituted Tetrahydrofuran Derivatives
作者:Andreas Schmitt、Hans-Ulrich Reißig
DOI:10.1002/1099-0690(200012)2000:23<3893::aid-ejoc3893>3.0.co;2-e
日期:2000.12
Monosubstituted γ-lactols 1a−1c, 3a−3c and 4a−4c, as well as disubstituted γ-lactol 5 and the γ-hydroxy-substituted γ-lactone 6, were transformed into disubstituted tetrahydrofuran derivatives by treatment with allyl- and propargylsilanes in the presence of Lewis acids. The diastereoselectivities were moderate to excellent and are interpreted by application of the Felkin−Anh model to cyclic oxocarbenium
单取代的 γ-乳醇 1a-1c、3a-3c 和 4a-4c,以及双取代的 γ-乳醇 5 和 γ-羟基取代的 γ-内酯 6,通过用烯丙基-和炔丙基硅烷处理转化为双取代的四氢呋喃衍生物。路易斯酸的存在。非对映选择性中等至极好,可以通过将 Felkin-Anh 模型应用于环状氧碳鎓离子来解释。讨论了中间体构象异构体之间平衡的影响。在此基础上可以解释 4-取代 γ-内酯 3 令人惊讶的高非对映选择性。