Formation of an unexpected rearrangement product using Grubbs' second generation catalyst: 2-allyl-3,4-dihydro-2H-1,4-benzothiazines from diene precursors

Morgans G.L. ; Yadav D.B. ; Fernandes M.A. ; De Koning C.B. ; Michael J.P. ; Van Otterlo W.A.L. (2012)


Application of sub-stoichiometric amounts of Grubbs' second generation catalyst to the substrate N-allyl-N-[2-(allylsulfanyl)phenyl]-4- methylbenzenesulfonamide afforded the ring-closed compound 6-[(4-methylphenyl) sulfonyl]-5,6-dihydro-2H-1,6-benzothiazocine, as well as the unexpected 2-allyl-4-[(4-methylphenyl)sulfonyl]-3,4-dihydro-2H-1,4-benzothiazine. Use of similar conditions on an analogous sulfoxide resulted in the expected product, 6-[(4-methylphenyl)sulfonyl]-5,6-dihydro-2H-1,6-benzothiazocine 1-oxide, indicating that the sulfide was playing a key role in this novel transformation. Furthermore, the use of N-allyl-4-methyl-N-{2-[(2-methyl-2-propenyl)sulfanyl] phenyl}-benzenesulfonamide in the same reaction gave 2-(2-methyl-2-propenyl)-3, 4-dihydro-2H-1,4-benzothiazine. © 2012 Elsevier Ltd. All rights reserved.

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