1-METHOXY-1-TRIMETHYLSILYLOXYPROPENE

1-Methoxy-1-(trimethylsilyloxy)propene is used to reactive nucleophile in Mukaiyama-type aldol reactions with aldehydes, imines, acetals, dialkoxycarbenium ions, and orthoesters; Michael-type additions to α,β-unsaturated carbonyl compounds; substitution reactions with allylic alcohols and esters; acylations; aminations; hydroxylations; and pericyclic reactions; silylating agent.

since the first preparation of a ketene trialkylsilyl acetal by Petrov in 1959 by the reaction of triethylsilane and methyl acrylate, several alternative pathways have been explored. Ainsworth and coworkers prepared 1-methoxy-1-(trimethylsilyloxy)propene in 90% yield by deprotonation of methyl propionate with Lithium Diisopropylamide at -78 °C followed by addition of Chlorotrimethylsilane. Reaction of the lithium enolate of methyl acetate with TMS-Cl provides 65% O-silylated and 35% C-silylated products (eq 1). Substitution on the alcohol portion of the ester favors C-silylation while substitution on the α-carbon favors O-silylation. An increase in the steric bulk of the silylating agent (e.g. use of t-Butyldimethylchlorosilane) results in significantly more O-silylation.

1-Methoxy-1-(trimethylsilyloxy)propene is easily hydrolyzed and oxidized by exposure to air. Storage is possible in sealed tubes at rt. Use in a fume hood.