A new route to silyl-substituted cyclobutenones and silylketenes
作者:Konstantin Benda、Tanja Knoth、Rick L. Danheiser、Ernst Schaumann
DOI:10.1016/j.tetlet.2010.10.130
日期:2011.1
2-Silyl-cyclobutene(di)ones are obtained by an addition/substitution approach on dimethyl squarate using silyl anions. The acetal and in particular the thioacetal derivatives readily undergo electrocyclic ring opening to reactive silyl(vinyl)ketenes.
An easy procedure for the synthesis of electron-poor 2-aza-1,3-dienes from silylimines is described; the ability of these azadienes to undergo cycloaddition to electron-rich alkenes is demonstrated for the first time.
Palladium‐Catalyzed Cascade Heck Coupling and Allylboration of Iododiboron Compounds via Diboryl Radicals
作者:Yi Wei、Xiao‐Yu Xie、Jiabin Liu、Xiaoxiao Liu、Bo Zhang、Xin‐Yi Chen、Shi‐Jun Li、Yu Lan、Kai Hong
DOI:10.1002/anie.202401050
日期:2024.4.24
Geminal bis(boronates) are versatile synthetic building blocks in organic chemistry. The fact that they predominantly serve as nucleophiles in the previous reports, however, has restrained their synthetic potential. Herein we disclose the ambiphilic reactivity of α‐halogenated geminal bis(boronates), of which the first catalytic utilization was accomplished by merging a formal Heck cross‐coupling with a highly diastereoselective allylboration of aldehydes or imines, providing a new avenue for rapid assembly of polyfunctionalized boron‐containing compounds. We demonstrated that this cascade reaction is highly efficient and compatible with various functional groups, and a wide range of heterocycles. In contrast to a classical Pd(0/II) scenario, mechanistic experiments and DFT calculations have provided strong evidence for a catalytic cycle involving Pd(I)/diboryl carbon radical intermediates.