PYRANYLIDENE IMINIUM SALTS .I. IMINIUM SALTS DERIVED FROM ALKYL-SUBSTITUTED PYRYLIUM SALTS AND THEIR HYDROLYSIS PRODUCTS

Pyrylium salts containing an active methyl group give monoiminium salts with N,N-dimethylformamide in acetic anhydride and bisiminium salts with the Vilsmeier complex. Methylene pyrylium salts yield monoiminium salts with the Vilsmeier complex. Monoiminium salts are obtained from alkylpyrylium salts and either N,N-dimethylthioacetamide in acetic anhydride or N,N-dialkylamides in the presence of phosphorus oxychloride. Vinylogs of certain of the monoiminium salts are obtained from alkylpyrylium compounds and diethylaminoacrolein in acetic anhydride. The iminium salts are hydrolyzed to give, in most cases, aldehydes and ketones. The hydrolysis products obtained from the iminium salt derived from 2-methyl-4,6-diphenylpyrylium perchlorate are 2-formylmethylidene-4,6-dipheny1-2H-pyran,4-dimethylamino-2-phenylbenzophenone, and 4-methoxy-2-phenylbenzophenone. © 1969, American Chemical Society. All rights reserved.