Cai-Zhu Chang

An environmentally benign and efficient synthesis of substituted benzothiazole-2-thiols, benzoxazole-2-thiols, and benzimidazoline-2-thiones in water

An efficient and practical method for the one-step synthesis of benzothiazole-2-thiols, benzoxazole-2-thiols and benzimidazoline-2-thiones by cyclization of 2-aminothiophenols, 2-aminophenols, and 1,2-phenylenediamines with tetramethylthiuram disulfide (TMTD) in water was described. The features of this method include metal/ligand-free, excellent yield, short reaction time and broad substrate scope. The method provides a facile and convenient preparation of some potentially biologically active compounds.

Copper-catalyzed tandem reaction of 2-haloanilines with thiocarbamoyl chloride: Synthesis of 2-aminobenzothiazoles

ABSTRACT A simple and efficient protocol for the synthesis of 2-aminobenzothiazoles by a ligand-free copper-catalyzed tandem reaction has been developed. In the presence of CuBr and t-BuOK, a variety of 2-haloanilines (halogen = Br, I) underwent the reaction with thiocarbamoyl chloride efficiently to afford the corresponding 2-aminobenzothiazoles in good yields (83–94%). The features of this method include good yield, cheap catalyst, mild reaction conditions, and broad substrate scope, which make the protocol practical and attractive in the preparation of some potential pharmaceutically active compounds. GRAPHICAL ABSTRACT

Metal-free or transition-metal-catalyzed one-pot synthesis of 2-aminobenzothiazoles

A series of 2-aminobenzothiazoles were synthesized by using 2-halogen-substituted anilines (halogen = Cl, Br, I) and dithiocarbamates in the presence of KOt-Bu. This simple and efficient protocol lets the reactions undergo in a smooth and rapid way to afford the corresponding 2-aminobenzothiazoles in good yields. It is noteworthy that the present process allows the construction of 2-aminobenzothiazoles from a wide range of 2-halogen-substituted aniline derivatives, including substituted 2-iodoanilines, 2-bromoanilines and 2-chloroanilines. GRAPHICAL ABSTRACT

Copper-Catalyzed and Air-Mediated Mild Cross-Dehydrogenative Coupling of Aryl Thioureas and Dialkyl H-Phosphonates: The Synthesis of Thiophosphonates

A copper-catalyzed and air-mediated mild cross-dehydrogenative coupling of aryl thioureas and dialkyl H-phosphonates to produce thiophosphonates has been reported. Without addition of base or acid, air as an oxidant, the phosphorylation occurred smoothly to give the target products in moderate to excellent yields at room temperature. The protocol allows the direct formation of a sulfur-phosphorus bond, tolerates a series of functional groups, and shows potential synthetic value for the synthesis of a diversity of thiophosphonates.

Copper-catalyzed amidation of benzoic acids using tetraalkylthiuram disulfides as amine sources

ABSTRACT A facile method for the copper-catalyzed synthesis of N-substituted benzamides was explored. In the presence of CuBr and di-tert-butyl peroxide, various N-substituted benzamides were prepared through amidation of benzoic acid by using commercially available and cheap tetraalkylthiuram disulfides as amine sources. With this protocol, a series of 14 N-substituted benzamides were furnished in good to excellent yields. The broad substrate scope and good to excellent yield show its practical synthetic value in organic synthesis. GRAPHICAL ABSTRACT