Gao Xing, Li Zhen, Yang Wenjun, Liu Yang, Chen Wufeng, Zhang Cheng, Zheng Lufei, Guo Hongchao
Department of Applied Chemistry, China Agricultural University, Beijing 100193, China.
Org Biomol Chem. 2017 Jun 27;15(25):5298-5307. doi: 10.1039/c7ob01034f.
The phosphine-catalyzed [3 + 2] annulation reaction of ynones and barbiturate-derived alkenes has been developed with the assistance of a weak acid, giving functionalized spirobarbiturate-cyclopentanones in moderate to excellent yields with excellent E/Z stereoselectivity. An unprecedented [4 + 2] annulation of ynones with barbiturate-derived alkenes was also achieved in the presence of a phosphine catalyst and an inorganic base, affording biologically interesting 1,5-dihydro-2H-pyrano[2,3-d]pyrimidine-2,4(3H)-dione derivatives. An asymmetric variant of the [3 + 2] annulation reaction has been explored and a moderate enantioselectivity was obtained when a bifunctional chiral phosphine was used as a chiral catalyst. A plausible mechanism was proposed to illuminate two different reaction pathways.
在弱酸的辅助下，开发了膦催化的炔酮与巴比妥酸衍生烯烃的[3 + 2]环化反应，以中等至优异的产率和出色的E/Z立体选择性得到官能化的螺巴比妥酸-环戊酮。在膦催化剂和无机碱存在下，还实现了炔酮与巴比妥酸衍生烯烃前所未有的[4 + 2]环化反应，得到具有生物学意义的1,5-二氢-2H-吡喃并[2,3-d]嘧啶-2,4(3H)-二酮衍生物。已探索了[3 + 2]环化反应的不对称变体，当使用双功能手性膦作为手性催化剂时，获得了中等的对映选择性。提出了一个合理的机理来阐明两条不同的反应途径。
