The reaction of 2,1-benzisothiazoline-3-thiones with acetylenic reagents

N-Methyl-2,1-benzisothiazoline-3-thione reacts with acetylene esters to form o-iminobenzoquinone methides which either form diazocines 2 by head-to-tail dimerisation, or react further with the acetylenic ester forming diadducts. With phenylacetylene a 1,2-difhiolo[2,3-b]2,1-benzisofhiazole structure...

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Veröffentlicht in:Canadian journal of chemistry 1987-06, Vol.65 (6), p.1247-1253
Hauptverfasser: Mckinnon, David M, Secco, Anthony S, Duncan, K. Ann
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Sprache:eng
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Zusammenfassung:N-Methyl-2,1-benzisothiazoline-3-thione reacts with acetylene esters to form o-iminobenzoquinone methides which either form diazocines 2 by head-to-tail dimerisation, or react further with the acetylenic ester forming diadducts. With phenylacetylene a 1,2-difhiolo[2,3-b]2,1-benzisofhiazole structure is obtained by rearrangement of an initial adduct. Related thiones and acetylenes react similarly but in poorer yields. The crystal and molecular structures of the diazocine were determined by single crystal X-ray diffractometry techniques. The compound crystallizes in space group with unit cell dimensions a = 7.9465(10), b = 13.6421(14), c = 13.9183(18) Å, α = 82.38(1), β = 83.67(1), γ = 85.77(1) deg, and Z = 2. The structure was solved by direct methods and refined to an R value of 0.056 for 3037 observed reflections. The structure consists of molecules of 2 a which have an approximate C 2 axis passing through the center of the eight-membered ring. Deviations from true symmetry result from internal ring strain, lone pair-lone pair repulsions, and packing effects.
ISSN:0008-4042
1480-3291
DOI:10.1139/v87-211