Cyclization Reactions through the SRN1 Mechanism. Reactions of o-Dihaloaromatic Compounds with Dithiolate Ions

Article abstract of DOI:10.1021/jo00382a021

In the present paper we report the reactions of o-dihaloaromatic compounds with dithiolate ions as new cyclization reactions occuring by the S_RN1 mechanism. o-Diiodo- and o-bromochlorobenzene react under photostimulation with 3,4-toluenedithiolate ion to give good yields (ca. 60percent) of the cyclic disubstituted compound 2-methylthianthrene.The reaction occurs to a lesser extent (ca. 20percent) when the substrate was 1-bromo-2-iodonaphthalene. 2,3-Dichloroquinoxaline reacts with the same nucleophile in the dark or in the presence of radical traps to give a 100percent yield of the cyclic disubstituted compound.The reaction of o-diiodobenzene with 1,2-ethanedithiolate gave a low yield of the cyclic compound benzo-1,4-dithiane.This decrease was explained in terms of fragmentation reactions of the proposed radical anions intermediates.