Abstract Several 1, 1-bis (trimethylenedioxyboryl)-1-alkenes (II) have been prepared and converted efficiently to 1, 1-bis (chloromercuri)-1-alkenes (III) by reaction with mercuric chloride and sodium acetate in aqueous methanol. Preparations of a 1, 1-diiodo-1-alkene (IV) and three 1, 1-bis (ethylenedioxyboryl)-1-alkenes are also described.