of boronated phosphines with an o-phenylene-bridge prepared from sec-phosphine boranes and using benzyne chemistry is reported. Successive reactions of sec-phosphine boranes with n-BuLi and 1,2-dibromobenzene, and then with boron reagents, afford the o-boronatophenylphosphine derivatives in 71% yields. The use of P-chirogenic sec-phosphine boranes leads to the free boronated phosphines with retention
oxide bifunctional ligand, have been developed for site-selectiveC−H alkenylation of N-heteroarenes with alkynes. Pyridines, pyridones, and imidazo[1,2-a]pyridines are efficiently alkenylated at the C−H site proximal to the Lewis basic nitrogen or oxygen. A ligand-to-ligand hydrogen transfer process is proposed as a general mechanism of these C−H activations.
Stereoselective Synthesis of P-Chirogenic Dibenzophosphole–Boranes via Aryne Intermediates
作者:Vincent Diemer、Anaïs Berthelot、Jérôme Bayardon、Sylvain Jugé、Frédéric R. Leroux、Françoise Colobert
DOI:10.1021/jo3009098
日期:2012.7.20
A new aryne-mediated tandem cross-coupling/P-cyclization sequence starting from tertiary phosphine-boranes and 1,2-dibromobenzenes is reported. P-chirogenic dibenzophospholes become accessible in a regio-, chemo-, and diastereoselectiye way.