Deprotonative Metalation of Chloro- and Bromopyridines Using Amido-Based Bimetallic Species and Regioselectivity-Computed CH Acidity Relationships
作者:Katia Snégaroff、Tan Tai Nguyen、Nada Marquise、Yury S. Halauko、Philip J. Harford、Thierry Roisnel、Vadim E. Matulis、Oleg A. Ivashkevich、Floris Chevallier、Andrew E. H. Wheatley、Philippe C. Gros、Florence Mongin
DOI:10.1002/chem.201101993
日期:2011.11.18
A series of chloro‐ and bromopyridines have been deprotometalated by using a range of 2,2,6,6‐tetramethylpiperidino‐based mixed lithium–metal combinations. Whereas lithium–zinc and lithium–cadmium bases afforded different mono‐ and diiodides after subsequent interception with iodine, complete regioselectivities were observed with the corresponding lithium–copper combination, as demonstrated by subsequent
A study on the BF3 directed lithiation of 3-chloro- and 3-bromopyridine
作者:Jaspreet S. Dhau、Amritpal Singh、Yoganjaneyulu Kasetti、Sonam Bhatia、Parsad V. Bharatam、Paula Brandão、Vítor Félix、Kamal N. Singh
DOI:10.1016/j.tet.2013.10.026
日期:2013.12
The BF3-directed lithiation of 3-chloro- and 3-bromopyridine (1a and 1b, respectively) has been investigated. The reactions of 3-chloro- or 3-bromopyridine–BF3 adduct with LDA (1.3/1.1 equiv) followed by quenching with benzaldehyde or iodine exclusively gave the C-2 substituted products. However, when 2.2 equiv of LDA and dimethyl disulfide was used, a C-6 substituted product was obtained. Dilithiation