Investigation of the reaction of 2-bromo-1-naphthol with arylacetonitriles and LiTMP: facile synthesis of 3-arylmethyl-1-hydroxynaphthalene-2-carbonitriles

Abstract

2-Bromo-1-naphthol reacts with arylacetonitriles and 3-thienylacetonitrile in the presence of LiTMP to give the rearranged 3-benzyl-1-hydroxynaphthalene-2-carbonitriles and 11-amino-5H-anthra[2,3-b]thiophen-10-one, respectively. The reactions proceed via a tandem addition–rearrangement pathway involving a non-synchronous [2 + 2] cycloaddition of an N-lithiated ketenimine and 2,3-didehydronaphthalene 1-oxide. An explanation of the orientation to and reactivity of the aforementioned aryne is presented in terms of chelation between the OLi group and the attacking nitrile nucleophile. Support for the intermediacy of 2,3-didehydronaphthalene 1-oxide was accomplished by obtaining 3-amino-1-naphthols from the reaction of 2-bromonaphthol and the appropriate lithium amide. Alternate non-aryne mechanisms were addressed, but were rejected based on experimental results.