Peterson olefination of aldehydes and ketones with trimethylsilyl(meth
oxy)(benzo triazol-1-yl)methyl anion 6 afforded 1 -(benzo-triazol-1-yl
)-1-methoxyalk-1-enes 7 which were treated without isolation with zinc
bromide and hydrochloric acid, to yield the corresponding one-carbon
homologated carboxylic acids 4 in good overall yields.