title: Rhodium-Catalyzed Regioselective Synthesis of Isocoumarins through Benzothiadiazine-Fused Frameworks.
abstract: An unprecedented two-step, one-pot synthesis of benzimidazothiadiazine 5,5-dioxides is presented. Reaction condition based regioselectivity has been achieved where fused benzimidazo[1,2-b][1,2,4]thiadiazines are exclusively formed under thermal conditions, whereas benzimidazo[2,1-c][1,2,4]thiadiazines were created only under microwave irradiation. The salient features of this protocol include a regioselective sulfonylation of 2-aminobenzimidazole with o-halo sulfonyl chlorides followed by N-C bond formation. The acid forms of these fused regioisomers have been used to introduce novel guanidine-containing isocoumarin frameworks.
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan, ROC.
authors.forename: Prashant B
authors.initials: PB
authors.lastname: Dalvi
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan, ROC.|Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , 100 Shih-Chuan First Road, Kaohsiung 807-08, Taiwan, ROC.
authors.forename: Kuang-Ling
authors.initials: KL
authors.lastname: Lin
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan, ROC.
authors.forename: Manohar V
authors.initials: MV
authors.lastname: Kulkarni
authors.affiliation: Department of Applied Chemistry, National Chiao-Tung University , 1001 Ta-Hseuh Road, Hsinchu 300-10, Taiwan, ROC.|Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , 100 Shih-Chuan First Road, Kaohsiung 807-08, Taiwan, ROC.
authors.forename: Chung-Ming
authors.initials: CM
authors.lastname: Sun