New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

• Qiuping Ding,
• Yuqing Lin,
• Guangni Ding,
• Fumin Liao,
• Xiaoyan Sang and
• Yi-Yuan Peng

Beilstein J. Org. Chem. 2013, 9, 460–466, doi:10.3762/bjoc.9.49

• and efficient method to construct ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives has been developed from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles under mild conditions, without the need for a metal catalyst. The newly developed method

• tolerates a wide range of substrates in moderate to excellent yields. Moreover, this method is advantageous over previous ones for the easy synthesis of reactants. Keywords: 4H-3,1-benzothiazine-2-thione; carbon disulfide; (E)-3-(2-aminoaryl)acrylate; (E)-3-(2-aminoaryl)acrylonitrile; Michael addition

• their preparation have been reported in the literature [9][10][11][12][13][14][15]. 4-Alkyl-4H-3,1-benzothiazine-2-thiones are an important class of 4H-3,1-benzothiazine derivatives. Therefore, 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives are also of potential biological importance. However, only a