Synthesis of Benzo[b]thiophenes through Rhodium‐Catalyzed Three‐Component Reaction using Elemental Sulfur

Abstract

A benzo [b]thiophene synthesis by Rhcatalyzed three-component coupling reaction of arylboronic acids, alkynes, and elemental sulfur (S 8 ) is developed. A notable feature of this protocol is that the thienannulation (thiophene annulation) proceeds with high regioselectivity via the sequential alkyne insertion, CÀ H activation, and then sulfur atom transfer to the metallacycle intermediate. In a similar manner, dibenzothiophenes can be synthesized from the parent biarylboronic acids and S 8 .

Recent Advances in the Synthesis of Heterocycles via Reactions Involving Elemental Sulfur

“…Very recently, Miura et al proposed a synthesis of benzothiophene 52 by rhodium-catalyzed three-component coupling reaction of arylboronic acids 50, alkynes 52, and elemental sulfur with silver acetate as oxidant (Scheme 19). [18] An interesting feature of this method is the formation of benzothiophenes 52 a with high regioselectivity when non symmetrical alkynes were used. The reaction proceeded via a sequence of alkyne insertion, CÀ H activation, and then sulfur atom transfer to the metallacycle intermediate.…”

Recent Advances in Multicomponent Reactions with Organic and Inorganic Sulfur Compounds

“…Miura et al reported a rhodium‐catalyzed three‐component reaction using arylboronic acids, alkynes, and elemental sulfur (S 8 ) to synthesize benzo[b]thiophenes 21 (Scheme 5). [36] …”

Rhodium-Catalyzed Synthesis of Organosulfur Compounds Involving S-S Bond Cleavage of Disulfides and Sulfur

“…A strong metal oxidizing reagent is an equivalent of a large amount of energy, and a related discussion will be provided in Section 8 on the use of the strong metal base of sodium hydroxide (Scheme 47). Rhodium-catalyzed organothiolation reactions of heteroarenes and related compounds using disulfides [79][80][81][82][83][84][85][86][87][88][89] and sulfur [90] have recently been reported. These methods employ stoichiometric or substoichiometric amounts of copper(II) or silver(I) salts.…”

“…Rhodium-catalyzed organothiolation reactions of heteroarenes and related compounds using disulfides [ 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ] and sulfur [ 90 ] have recently been reported. These methods employ stoichiometric or substoichiometric amounts of copper(II) or silver(I) salts.…”