TMSCH2Li–LiDMAE: a new nonnucleophilic reagent for C-2 lithiation of halopyridines
摘要:
A new superbasic reagent has been discovered by combining TMSCHL(2)i and LiDMAE in hexane. This reagent was found highly efficient for the C-2 lithiation of sensitive chloro- and fluoropyridines. The metallation occurred chemo- and regioselectively at 0 degrees C avoiding the nucleophilic addition or substrate degradation commonly obtained with other alkyllithiums even at lower temperatures. (c) 2006 Elsevier Ltd. All rights reserved.