A DFT study of NHC-catalyzed reactions of [3+3] annulations of 2-bromoenals and thioamides: mechanisms and regio- and stereoselectivities

Yan Li*, Lina Geng, Zhiyi Song, Zhiqiang Zhang*

*此作品的通讯作者

科研成果: 期刊稿件文章同行评审

2 引用 (Scopus)

摘要

We present a density functional theory study to characterize the possible mechanisms and origins of regio- and stereoselectivities of N-heterocyclic carbene (NHC)-catalyzed reactions of 2-bromoenals with thioamides leading to the formation of 1,3-thiazin-4-ones. According to DFT results, the energetically favorable mechanism involves the following elementary steps: formation of a Breslow intermediate via coordination of the NHC to 2-bromoenal followed by 1,2-proton transfer. Debromination followed by 1,3-proton transfer generates the α,β-unsaturated acylazolium intermediate, which further undergoes thia-Michael addition to thioamide forming the enolate intermediate. Subsequent 1,5-proton transfer and intramolecular cyclization give the six-membered ring intermediate, which upon elimination of NHC leads to the formation of 1,3-thiazin-4-one. The thia-Michael addition step was identified as the regio- and stereoselectivity-determining step, affording the S-configurational product preferentially, in agreement with previous experimental observations. According to NCI analysis, the stronger non-covalent interactions such as CH⋯π, LP⋯π and π⋯π interactions lead to the lower energy of the transition state that corresponds to the major stereoisomer of 1,3-thiazin-4-one.

源语言英语
页(从-至)21815-21824
页数10
期刊New Journal of Chemistry
47
47
DOI
出版状态已出版 - 9 11月 2023
已对外发布

指纹

探究 'A DFT study of NHC-catalyzed reactions of [3+3] annulations of 2-bromoenals and thioamides: mechanisms and regio- and stereoselectivities' 的科研主题。它们共同构成独一无二的指纹。

引用此