An expedient synthesis of cyanoformates via DAST-mediated C-C bond cleavage of α-oximino-β-ketoesters

A new protocol to synthesize cyanoformates was developed using simple beta-ketoesters as substrates. (Diethylamino)sulfur trifluoride (DAST) was used as a dual-role reagent to activate the oxime moiety and to donate a fluoride. The key intermediates, alpha-oximino-beta-ketoesters, were prepared by highly efficient acid-assisted oximation of beta-ketoesters. Then, the deconstruction of alpha-oximino-beta-ketoesters by the fluorinative C-C bond cleavage was demonstrated to provide cyanoformates. In this event, the fluoride addition followed by the C-C bond cleavage selectively occurred in the ketones over esters. Due to simple and mild reaction conditions, variously functionalized cyanoformates were exemplified. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A new protocol for synthesizing cyanoformates was developed using simple beta-ketoesters as substrates. The key intermediates were prepared by efficient acid-assisted oximation of beta-ketoesters. The deconstruction of the intermediates provided cyanoformates due to fluoride addition and C-C bond cleavage. Various functionalized cyanoformates were exemplified under simple and mild reaction conditions.