A simple method for the synthesis of l,3-dioxolanes from carbonyl compounds has been developed using l,2-bis(trimethylsilyloxy) ethane in the presence of bismuth (III) triflate as a catalyst. The bismuth(III) triflate catalyzed synthesis of a range of dioxanes and dioxepines has also been developed. In these latter cases, the carbonyl compound is treated with a diol, and triethyl orthoformate is used as a water scavenger. All these methods avoid the use of a Dean-Stark trap.