Methyleneketenes and methylenecarbenes. V. Condensation of ketones with isopropylidene malonate catalysed by titanium tetrachloride and synthesis of a dibenzofuran

Abstract

The TiCl4/pyridine/tetrahydrofuran reagent of Lehnert will effect direct condensation of some aromatic ketones with isopropylidene malonate (Meldrum's acid). The synthetic value of this reaction is explored in a synthesis of 7-methoxy-9-methyldibenzofuran-3-ol involving two pyrolytic steps and using only aliphatic precursors. A 1,9-dimethyldibenzofuran related to strepsilin could not be obtained in the same way.