Alkylidenation of Ester Carbonyl Groups by means of a Reagent Derived from RCHBr2, Zn, TiCl4, and TMEDA. Stereoselective Preparation of (Z)-Alkenyl Ethers
Reagents prepared by reduction of 1,1-dibromoalkanes (R3CHBr2) with zinc and TiCl4 in the presence of N,N,N',N'-tetramethylethylenediamine in THF are effective in the conversion of esters (R1CO2R2) to the corresponding alkenyl ethers (R1(R2O)C=CHR3) with high Z selectivity.