Tf2O-Mediated Cyclization of α-Acyl-β-(2-aminopyridinyl)acrylamides: Access to N-Substituted 4 H-Pyrido[1,2- a]pyrimidin-4-imines

Chitturi Bhujanga Rao; Ning Zhang; Jiana Hu; Yu Wang; Yongjiu Liang; Rui Zhang; Jingwen Yuan; Dewen Dong

doi:10.1021/acs.joc.9b03495

Tf₂O-Mediated Cyclization of α-Acyl-β-(2-aminopyridinyl)acrylamides: Access to N-Substituted 4 H-Pyrido[1,2- a]pyrimidin-4-imines

J Org Chem. 2020 Apr 3;85(7):4695-4705. doi: 10.1021/acs.joc.9b03495. Epub 2020 Mar 17.

Authors

Chitturi Bhujanga Rao¹, Ning Zhang¹, Jiana Hu^{1

2}, Yu Wang^{1

2}, Yongjiu Liang¹, Rui Zhang¹, Jingwen Yuan¹, Dewen Dong^{1

2}

Affiliations

¹ CAS Key Laboratory of High-Performance Synthetic Rubber and Its Composite Materials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
² University of Science and Technology of China, Hefei 230026, P. R. China.

PMID: 32149512
DOI: 10.1021/acs.joc.9b03495

Abstract

A facile and efficient direct synthesis of N-substituted 4H-pyrido[1,2-a]pyrimidin-4-imines is developed from α-acyl-β-(2-aminopyridinyl)acrylamides mediated by triflic anhydride (Tf₂O) in the presence of 2-chloropyridine. This amide activation protocol features mild reaction conditions, simple execution, excellent yields, and high chemoselectivity, and is also applied to the synthesis of substituted 4H-pyrido[1,2-a]pyrimidin-4-ones via a practical one-pot procedure.

Publication types

Research Support, Non-U.S. Gov't