Phase Transfer Catalysis without Solvent. Synthesis of Bisazolylalkanes

Abstract

The reaction of asoles and benzasoles with dihalomethanes and dihaloethanes was performed in the absence of solvent.This 8ethod provides a general procedure for the synthesis of bisarolylmethanes and ethanes.No solvent was used during the reaction and, when possible, during the work-up.Polyazolylborate anions have been widely used as complexation agents.*As an extension N-h~polyazolylmethanes and -ethanes have a growing interest as neutral l i g a n d ~. ~ However, complex synthesis of the azolylalkanes and low yields reduced the usefulness of these compounds.The application of Phase Transfer Catalysis (P.T.C.) provided a useful method for the preparation of azolylmethanes.~This method was extended to various azoles, ~y r a z o l e s , ~ 1,2,4-triazole~,~ imidaso~es,~ henzotriazoles6 and also to tris-and tetralisazolylmethanes6*' and hisasol~lethanes.~The advantages of P.T.C. were, .orereadily available and less toxic reagents, easier experimental procedures, higher yields and a wider scope than previous ~t h o d s .~ Scheme 1We are interested in the use of azolylmethanes and -ethanes, in coordination chemistry, in deprotonation followed by electrophilic addition reactions and in the synthesis of azapentalene systems (Scheme 1).