Visible‐Light‐Promoted Cascade Coupling of 2‐Isocyanonaphthalenes with Elemental Sulfur and Amines to Construct Naphtho[2,1‐d]thiazol‐2‐Amines

A facile and efficient visible-light-induced three-component reaction has been developed for the synthesis of 2-aminonaphthothiazoles from 2-isocyanonaphthalenes, elemental sulfur, and amines. This photochemical transformation can be conducted under mild conditions without an external photocatalyst to afford various naphtho[2,1-d]thiazol-2-amines in moderate to excellent yields by using air as a green oxidant.

Abstract

A visible-light-induced strategy has been explored for the synthesis of naphtho[2,1-d]thiazol-2-amines through ortho-C−H sulfuration of 2-isocyanonaphthalenes with elemental sulfur and amines under external photocatalyst-free conditions. This three-component reaction, which utilizes elemental sulfur as the odorless sulfur source, molecular oxygen as the clean oxidant, and visible light as the clean energy source, provides a mild and efficient approach to construct a series of naphtho[2,1-d]thiazol-2-amines. Preliminary mechanistic studies indicated that visible-light-promoted photoexcitation of reaction intermediates consisting of thioureas and DBU might be involved in this transformation.

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