Issue 25, 2017

Phosphine-catalyzed [3 + 2] and [4 + 2] annulation reactions of ynones with barbiturate-derived alkenes

Abstract

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.

Graphical abstract: Phosphine-catalyzed [3 + 2] and [4 + 2] annulation reactions of ynones with barbiturate-derived alkenes

Supplementary files

Article information

Article type
Paper
Submitted
28 Apr 2017
Accepted
30 May 2017
First published
30 May 2017

Org. Biomol. Chem., 2017,15, 5298-5307

Phosphine-catalyzed [3 + 2] and [4 + 2] annulation reactions of ynones with barbiturate-derived alkenes

X. Gao, Z. Li, W. Yang, Y. Liu, W. Chen, C. Zhang, L. Zheng and H. Guo, Org. Biomol. Chem., 2017, 15, 5298 DOI: 10.1039/C7OB01034F

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