In Situ Generated 1-Naphthylmethyl Radicals from Bis(1-Naphthylmethyl)tin Dichlorides: Utilization for C−C, C−N, and C−O Bond-Forming Reactions

Abstract

The in situ-generated 1-naphthylmethyl radicals from the thermolysis of bis(1-naphthylmethyl)tin dichlorides combine with persistent organic radicals, 4-hydroxy-TEMPO or 4-oxo-TEMPO designs C−O bond forming products. Subsequently, the C−N bond occurs when the 1-naphthylmethyl radicals unite with nitric oxide (NO) under a nitrogen atmosphere. In contrast, the oxidation instead of the addition reaction predominantly happens in the 1-naphthylmethyl radicals when nitrogen dioxide contains a high oxidation state nitrogen center, i. e., N(IV) used. The by-product, dodecanuclear organotin cages, with twelve peripheral naphthyl units, could be isolated from the 4-hydroxy-TEMPO reaction. Besides, the synthesis of unsymmetrical diarylmethanes RArCH₂ (R=1-naphthyl, 2,4,6-Me₃C₆H₂, 3- and 4-MeC₆H₄, phenyl, 4-ClC₆H₄; Ar=4-MeOC₆H₄, 3,4-, 2,4- and 2,5-Me₂C₆H₃) in high yields and with good regioselectivity is reported. This new methodology involves the iodine-mediated thermolysis of bis(arylmethyl)tin dichlorides (RCH₂)₂SnCl₂ and an excess of an arene. This reaction involves homolytic cleavage of Sn−C bonds to give arylmethyl radicals that react with iodine in the presence of SnCl₂ to give the corresponding cations, which undergo electrophilic attack on the arene. Functionalised diarylmethanes have wide applications in pharmaceutical, agrochemical, and materials sciences. Alternative synthetic approaches to this class of organic compounds that avoid using a transition-metal catalyst or a strong Lewis acid are desirable.