The sequential treatment of terminal alkynes or propargylic alcohols with n-BuLi and MOMCl afforded the corresponding propargylic methyl ethers, which would react with primary alkyl Grignard reagents under the catalysis of CuBr to afford 3-substituted 1, 2-allenes or 2- substituted secondary 2, 3-allenols, respectively. The reaction may be applied to the synthesis of optically active 2-substituted secondary 2, 3-allenols with up to> 99% ee ...