A highly efficient strategy for the kinetic resolution of Michael adducts was realized using a chiral N‐heterocyclic carbene catalyst. The kinetic resolution provides a new convenient route to single diastereomers of cyclohexenes and Michael adducts in good yields with high enantiomeric excesses (up to 99 % ee with a selectivity factor of up to 458). This “two flies with one swat” concept allows the
One-Pot Cascade Heterocyclization of γ- and β-Ketomalononitriles to 2,4-Dichloro-Substituted Pyrano[2,3-<i>d</i>]pyrimidines and Furo[2,3-<i>d</i>]pyrimidines Mediated by Triphosgene and Triphenylphosphine Oxide
作者:Zhen-Hua Li、Zhi-Jiang Jiang、Qiao-Ling Shao、Jin-Jing Qin、Qiang-Feng Shu、Wen-Hao Lu、Wei-Ke Su
DOI:10.1021/acs.joc.8b00669
日期:2018.6.15
A one-pot cascade heterocyclization strategy has been developed for the synthesis of 2,4-dichloro-substituted pyrano[2,3-d]pyrimidines and furo[2,3-d]pyrimidines from linear γ- and β-ketomalononitriles using triphosgene and triphenylphosphine oxide. The reaction afforded synthetic useful products with moderate to good yields, bypassing the conventional harsh conditions of chlorination. The mechanistic
已开发出一锅级联杂环化策略,使用三光气从线性γ-和β-酮基乙腈合成2,4-二氯取代的吡喃并[2,3- d ]嘧啶和呋喃并[2,3- d ]嘧啶和三苯基氧化膦。该反应绕开了常规的苛刻氯化条件,提供了具有中等至良好收率的合成有用产物。机理研究表明反应是通过非异氰酸酯途径进行的,第二步可能以三苯膦氧化物催化的方式进行。
Bifunctional Tertiary Phosphine-Catalyzed Cascade Michael–Henry Reaction of a β-Nitroolefin and a 2-(1-Substituted 3-oxo-3-phenylpropyl)malononitrile
作者:De-Qing Shi、Ying Wang、Wei Yuan、Hu-Fei Zheng
DOI:10.1055/s-0032-1317956
日期:——
The bifunctional phosphine catalyst 2'-(diphenylphosphino)biphenyl-2-ol was used in an effective synthesis of highly functionalized cyclohexanols through a cascade Michael-Henry reaction of a beta-nitroolefin and a 2-(1-substituted 3-oxo-3-phenylpropyl)malononitrile. The method has the advantages of requiring mild conditions and providing a convenient workup, high diastereoselectivity, good atom economy, and a wide substrate scope, rendering it useful for the synthesis of highly functionalized cyclohexanols.