Title of article :
Regioselective construction of six-membered fused heterocyclic rings via Pd/C-mediated C–C coupling followed by iodocyclization strategy: a new entry to 2H-1,2-benzothiazine-1,1-dioxides
Author/Authors :
Deepak Kumar Barange، نويسنده , , Venkateswara Rao Batchu، نويسنده , , Dhillirao Gorja، نويسنده , , Vijaya Raghavan Pattabiraman، نويسنده , , Lakshmi Kumar Tatini، نويسنده , , J. Moses Babu، نويسنده , , Manojit Pal، نويسنده ,
Issue Information :
هفته نامه با شماره پیاپی سال 2007
Abstract :
We describe a practical and elegant method of constructing a thiazine ring fused with benzene under mild reaction conditions. A variety of 4-iodo-2H-benzo[e][1,2]thiazine-1,1-dioxides were prepared with high regioselectivity via a two-step process involving Pd/C-mediated C–C coupling of o-halobenzenesulfonamides with terminal alkynes, followed by iodocyclization of the resulting o-(1-alkynyl)arenesulfonamide using elemental iodine in acetonitrile. The coupling reaction was carried out using 10% Pd/C–PPh3–CuI as a catalyst system in the presence of Et3N. The process worked well for bromides and iodides, and a wide array of terminal alkynes containing alkyl and aryl substituents were employed. The iodocyclization step tolerated a variety of functional groups such as hydroxy, chloro, cyano, and methoxy, producing the six-membered heterocyclic ring selectively. The resulting 4-iodo-2H-benzo[e][1,2]thiazine-1,1-dioxides participated in Sonogashira, Heck, and Suzuki reactions producing a wide range of functionally substituted benzothiazines in good yields.
Keywords :
2]thiazine-1 , o-Halobenzenesulfonamide , 1-dioxides , terminal alkynes , Palladium catalyst
Journal title :
Tetrahedron
Journal title :
Tetrahedron