Center for Chemical Methodology and Library Development (CMLD-BU), Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
J Org Chem. 2010 Jul 2;75(13):4584-90. doi: 10.1021/jo100889c.
Asymmetric scandium(III)-catalyzed rearrangement of 3-allyloxyflavones was utilized to prepare chiral, nonracemic 3,4-chromanediones in high yields and enantioselectivities. These synthetic intermediates have been further elaborated to novel heterocyclic frameworks including angular pyrazines and dihydropyrazines. The absolute configuration of rearrangement products was initially determined by a nonempirical analysis of circular dichroism (CD) using time-dependent density functional theory (TDDFT) calculations and verified by X-ray crystallography of a hydrazone derivative. Initial studies of the mechanism support an intramolecular rearrangement pathway that may proceed through a benzopyrylium intermediate.
不对称钪（III）催化的 3-烯丙氧基黄酮的重排反应被用于高效高对映选择性地制备手性、非外消旋的 3,4-色满二酮。这些合成中间体进一步被精心设计成包括角型吡嗪和二氢吡嗪在内的新型杂环骨架。重排产物的绝对构型最初通过使用含时密度泛函理论（TDDFT）计算的圆二色性（CD）的非经验分析来确定，并通过一个腙衍生物的 X 射线晶体学来验证。对反应机制的初步研究支持了一种可能通过苯并吡喃中间体进行的分子内重排途径。
