One-Pot Synthesis of Some New α-Bromoketals and Acetals via 1,8-Diazabicyclo[5.4.0] Undec-7-ene- Hydrobromide-Perbromide

摘要

alpha-Bromoketals and acetals are important synthetic precursors in organic synthesis. In this work, some new alpha-bromoketals are synthesized by the reaction of aryl methyl ketones with diols in the presence of 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) hydrobromide-perbromide in good isolated yields. The latter compound converts aldehydes to acetals and serves as a new and efficient reagent for the synthesis of acetals. Comparative studies of the preparation of a-bromoketal and acetals using some reported methods versus the present method show that DBUH-Br-3 is one of the most efficient reagents for the preparation of these compounds. Conversion of carbonyl compounds to corresponding alpha-bromoketals and acetals in the presence of DBUH-Br-3 under microwave irradiation is also described.