coupling of bis(phenylthio)methyltributylstannane with alcohols. The dithioorthoformates thus prepared are useful precursors for alkoxymethylidene complexes of titanium, which transform carbonylcompounds into a variety of enolethers. Even the alkoxymethylidene complexes having a terminal olefin moiety can be prepared and employed for carbonyl olefination without formation of ring-closing metathesis