ChemInform Abstract: Synthesis and Biological Activity of Fused Heterocycles Derived from Embelin.

Brahmeshwari, G.; Ramadevi, S.; Rao, M. S. Narasinga; Rao, T. V. P.

doi:10.1002/chin.199120167

Cited by 1 publication

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…BQ has two equivalent alkenic dipolarophiles [C(2)=C(3) and C(5)=C(6)], both of which are activated by adjacent electron-withdrawing carbonyl groups, and the carbonyl groups themselves are also potential dipolarophiles. Although BQ has proved to be an effective dipolarophile for cycloadditions to a variety of 1,3-dipoles, [9][10][11]41,42 there had been no reports of nitrile sulfides reacting with BQ prior to the present work.…”

Section: Methodsmentioning

confidence: 99%

Nitrile sulfides Part 16. Synthesis of 1,2-benzisothiazoles via nitrile sulfide cycloaddition reactions

Ross¹,

Delipala²,

Watson³

et al. 2013

Arkivoc

View full text Add to dashboard Cite

The cycloaddition reactions of nitrile sulfides have been used to prepare benzisothiazole quinones and 1,2-benzisothiazole-5,6-dicarboxylates. The nitrile sulfides, generated by thermal decarboxylation of 1,3,4-oxathiazol-2-ones, reacted with 1,4-naphthoquinone to afford 3-substituted naphtho [2,3-d]isothiazole-4,9-diones (17), together with nitriles as by-products. The corresponding reactions with 1,4-benzoquinone yielded regioisomeric mixtures of 2:1 adducts. The 1,2-benzisothiazole-5,6-dicarboxylates were synthesised by a sequence involving both nitrile sulfide and Diels-Alder cycloaddition reactions. Dimethyl 3-phenylisothiazole-4,5-dicarboxylate (34), prepared from benzonitrile sulfide and dimethyl acetylenedicarboxylate (DMAD), was converted into the 4,5-bis(dibromomethyl) analogue 37 via the bis(dihydroxymethyl) compound 35. Treatment of 37 with sodium iodide in the presence of DMAD afforded dimethyl 3-phenyl-1,2-benzisothiazole-5,6-dicarboxylate (30) via the isothiazole o-quinodimethane 32.

show abstract

Section: Methodsmentioning

confidence: 99%