Exploring the nucleophilicity of <i>N</i>,<i>N</i>′‐diamidocarbenes: Heteroallenes and related compounds as coupling reagents

Abstract

The propensity of a stable N , N ′‐diamidocarbene (DAC) to react with various heteroallenes was explored. The DAC condensed with 4‐nitrophenyl azide as well as 4‐nitrophenyl isothiocyanate to afford the respective acyclic triazene or zwitterionic dihydropyrimidinium imidothiolate products. Treating the DAC with two equivalents of 3‐nitrophenyl isocyanate afforded an iminooxazolidinone rather than the expected hydantoin. Similarly, the addition of diphenylketene to the DAC afforded a dioxolane product, whereas analogous reactions involving N‐heterocyclic carbenes (NHCs) resulted in betaine adducts. Although the DAC as well as various diaminocarbenes condensed with 2,6‐dimethoxyphenyl nitrile N ‐oxide to afford the respective nitrosoethylenes, only the six‐membered DAC and NHC adducts rearranged to the corresponding nitrones at elevated temperature. Copyright © 2012 John Wiley &amp; Sons, Ltd.