Synthesis and X-ray structure of a fluorinated 1,1-dialkoxy-3-iminoisoindoline acetal, an elusive phthalocyanine precursor

Abstract

The synthesis of a fluoroalkylated 1,1-dimethoxy-3-iminoisoindoline acetal, the first representative of the halogenated 3-imino-amino-1-acetal class is reported. In contrast to the protio compound, fluoroalkyl groups make the presence of a base unnecessary for its synthesis while stabilizing the amino tautomer as revealed by an X-ray structural analysis - the first atomic-level structural characterization of the 1,1-alkoxy-3-amino(imino) isoindoline scaffold. Dimers present in solid-state are H-bonded and define a motif similar to the stabilizing, reverse wobble one encountered in adenine-cytosine pairs of tRNA. The fluoro acetal forms easily both metallo- and metal-free phthalocyanines, supporting the proposal that acetals might be phthalocyanine intermediates.