Steric effects in the synthesis of ortho-substituted 1,1′-binaphthalene derivatives by the SRN1 and the Stille reaction

Abstract

The scope of the SRN1 mechanism and the Stille reaction to synthesize 1,1′-binaphthalene derivatives was investigated. The best yield of 2′-methoxy-1,1′-binaphthalenyl-2-ol (52%) was obtained in liquid ammonia or DMSO by the SRN1 irradiated reaction of 1-iodo-2-methoxynaphthalene with the anion of 2-naphthol. A lower yield (40%) of BINOL is obtained in water with 1-iodo-2-hydroxynaphthalene as substrate when the reaction is sonicated before irradiation. The Stille reaction between (2-methoxy-1-naphthyl)-trimethylstannane and 1-iodo-2-methoxynaphthalene afforded low yields (15-11%) of the 1,1′-binaphthalene derivative. Based on AM1 and B3LYP calculations the yields of the 1,1′-binaphthalene derivatives obtained through the electron transfer SRN1 reaction can be attributed to kinetic factors of the radical-nucleophile coupling step.