3-Bromopropenyl methyl carbonate reacts smoothly with aldehydes in the presence of zinc in a mixture of saturated aqueous NH4Cl and THF (9:1). Monoprotected alk-1-en-3,4-diols are formed in high yields and in short reaction times. The reaction is diastereoselective, saturated aldehydes afford anti-adducts, while α,β-unsaturated and aromatic aldehydes preferentially give the syn-isomers. Very simple conditions for the conversion of intermediate monocarbonate derivatives of alk-1-en-3,4-diols to cyclic carbonates are also reported.
zinc - 3-bromopropenyl carbonates - heterosubstituted allyl zinc complexes - water as solvent - monoprotected alk-1-en-3,4-diols