Enantioselective Carbonyl Allylation, Crotylation, and <i>tert</i>-Prenylation of Furan Methanols and Furfurals via Iridium-Catalyzed Transfer Hydrogenation
作者:Benjamin Bechem、Ryan L. Patman、A. Stephen K. Hashmi、Michael J. Krische
DOI:10.1021/jo902697g
日期:2010.3.5
identical conditions, the corresponding substituted furfurals 2a−c are converted to identical products of allylation, crotylation, and tert-prenylation. Optically enriched products of carbonyl allylation, crotylation, and reverse prenylation 3b, 4b, and 5b were subjected to Achmatowicz rearrangement to furnish the corresponding γ-hydroxy-β-pyrones 6a−c, respectively, with negligible erosion of enantiomeric
5-取代-2-呋喃甲醇1a - c在邻位环金属化铱存在下暴露于乙酸烯丙酯、α-甲基烯丙酯或 1,1-二甲基丙二烯后,会发生对映选择性羰基烯丙基化、巴豆基化和叔异戊二烯化分别由 ( R )-Cl、MeO-BIPHEP、( R )-C3-TUNEPHOS 和 ( R )-C3-SEGPHOS 改性的催化剂。在 2-丙醇存在下,但在其他条件相同的情况下,相应的取代糠醛2a - c被转化为相同的烯丙基化、巴豆化和叔-异戊二烯化。羰基烯丙基化、巴豆化和反向异戊二烯化的光学富集产物3b、4b和5b进行 Achmatowicz 重排,分别提供相应的 γ-羟基-β-吡喃酮6a - c,对映体过量的侵蚀可忽略不计。