Masuda borylation–Suzuki coupling (MBSC) sequence of vinylhalides and its application in a one-pot synthesis of 3,4-biarylpyrazoles
作者:Boris O. A. Tasch、Lisa Bensch、Dragutin Antovic、Thomas J. J. Müller
DOI:10.1039/c3ob41249k
日期:——
The Masuda borylationâSuzuki coupling (MBSC) sequence was successfully extended to the challenging coupling of vinylhalides with various (hetero)arylhalides using sterically hindered phosphane ligands. Starting from (hetero)arylhalides and α-bromocinnamaldehyde, the sequentially Pd-catalyzed process selectively furnishes α,β-substituted cinnamaldehydes without affecting the reactivity of the Michael system. These intermediates were implemented as entries into a novel synthesis of 3,4-diaryl 1H-pyrazoles in the fashion of a three-step one-pot procedure consisting of a Masuda borylationâSuzuki coupling and subsequent Michael additionâcyclocondensationâelimination sequence.
Masuda borylationâSuzuki 偶联(MBSC)序列成功地扩展到了使用立体受阻膦烷配体的乙烯基卤化物与各种(杂)芳基卤化物的高难度偶联。从(杂)芳基卤化物和δ-溴肉桂醛开始,在 Pd 催化下依次选择性地生成δ、δ² 取代的肉桂醛,而不会影响迈克尔体系的反应活性。这些中间体作为新合成 3,4-二芳基 1H-吡唑的入口,采用三步一步法合成,包括 Masuda 玻里化-铃木偶联和随后的迈克尔加成-环缩合-消除顺序。