Useful intermediate for the preparation of other ɑ-heterosubstituted acetaldehyde acetals, e.g. the corresponding thiol by reaction with sodium polysulfide and reductive cleavage with Na in liquid ammonia: Org. Synth. Coll., 4, 295 (1963). Precursor of the easily-polymerized ketene diethyl acetal, by dehydrobromination with KO-t-Bu: Org. Synth. Coll., 3, 506 (1965).