LDA (lithium diisopropylamide) mediated reactions of 1-naphthalynes with lithiated acetonitriles and 1,4-dipolar nucleophilic anions

Article abstract of DOI:10.1055/s-1993-25963

3-Bromo-2-methoxy-(5) and 3-bromo-2-methoxy-6-methylnaphthalene (6) yield 1-naphthalyne intermediates which react with various α-lithiated nitriles 10 to afford both rearranged 1-arylmethyl- or 1-hetarylmethyl-3-methoxynaphthalene-2-carbonitriles 11 and 12, respectively, and α-naphthylated aryl- or hetarylacetonitriles 13 and 14, respectively. Product distributions 11:13 favoring rearranged nitriles (65:35-90:10) were obtained from LDA-mediated reactions of 5 with arylacetonitriles 9a, b and thiopheneacetonitriles 9c, d. Similar treatment of 6 with 9a-d gave product distributions 12:14 heavily in favor of rearranged nitriles (> 90:10) presumably due to the ability of the additional 7-methyl group to increase the rate of cyclization of the initial aryne-nitrile anion adduct, the crucial step in the rearrangement pathway. However treatment of either 5 or 6 with α-lithiated pyridylacetonitriles 9e, f or 2-benzimidazolylacetonitrile (9g) gave product distributions 11:13 or 12:14, respectively, heavily in favor of α-naphthylated acetonitriles (30:70<10:90). Additionally, several precursors to methoxy-substituted 1-naphthalynes 5, 19 and 20 were found to undergo cycloaddition with the dipolar nucleophilic precursors 3-cyanophthalide (17) and α-cyano-o-tolunitrile (21) to give angularly substituted benz[a]anthracene derivatives 18, 22.