Transformations of 3-methyl-2-azafluorene involving the methyl and methylene groups

The condensation of 3-methyl-2-azafluorene with benzaldehyde at the methyl group, as a result of which the cis and trans forms of 3-styryl-2-azafluorene are formed, proceeds without catalysts. The subsequent condensation with benzaldehyde takes place in the presence of potassium ethoxide and leads to 3-styryl-9-benzylidene-2-azafluorene. Treatment of azafluorene with phenoxyacetyl chloride in the presence of triethylamine yielded 3-methyl-9-(α-hydroxy-β-phenoxyethylidene)-2-azafluorene. On the basis of the spectral data it was concluded that the latter exists in the form of a mixture of the enol form and the zwitterionic form. 3-Methyl-9-(γ-phenyl-α-cinnamoyloxyallylidene)-2-azafluorene was obtained by acylation of azafluorene with cinnamoyl chloride under the same conditions. The PMR and IR spectral data are presented. © 1978 Plenum Publishing Corporation.