Abstract:
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.
摘要:
Geminalbis(硼酸酯)是有机化学中的通用合成结构单元。在以前的报告中,它们主要用作亲核试剂,然而,抑制了他们的合成潜力。在这里,我们公开了α-卤化双二(硼酸)的两亲反应性,其中第一个催化利用是通过将形式的Heck交叉偶联与醛或亚胺的高度非对映选择性烯丙基硼化合并来实现的,为多官能化含硼化合物的快速组装提供了新的途径。我们证明了这种级联反应是高效的,并且与各种官能团相容,和广泛的杂环。与经典的Pd(0/II)方案相反,机理实验和DFT计算为涉及Pd(I)/二硼基碳自由基中间体的催化循环提供了有力的证据。