Sulfonamide and Tertiary Amine as Nucleophiles in Pd(II)-Catalyzed Diamination of Alkynes: Synthesis of Tetracyclic Indolobenzothiazine S,S-Dioxides.
Pd(II)-catalyzed oxidative double cyclization of the 1,2-diarylethynes bearing an N-methyl-N-(2-methoxycarbonyl)ethylamino and an aminosulfonyl group afforded indolobenzothiazine S,S-dioxides in good to excellent yields. The 2-(methoxycarbonyl)ethyl group attached to the indolyl nitrogen is readily removed under basic conditions (DBU, DMF, 120 °C) to provide the corresponding tetracycles with a free indolyl nitrogen in excellent yields.
Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne , EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
Tu M
TM
Ha
Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne , EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
Bo
B
Yao
Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne , EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
Qian
Q
Wang
Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne , EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
Jieping
J
Zhu