A new class of α,β‐unsaturated δ‐oxacaprolactams was synthesized from imines as starting material. The synthetic procedure is based on an acyl chloride addition in the first step, followed by a ring‐closing metathesis using a ruthenium catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Abstract:The structure of the product of the Asinger reaction of acetophenone with n-butylamine and elemental sulfur is still under debate. Two products have been proposed: a hexathiocanthione containing a C 2 S 6 ring with an exocyclic thione and a heptathiocane containing a CS 7 ring. A single crystal X-ray study has shown that the heptathiocane structure is correct.1 H and 13 C NMR investigations in solution confirm that the structure is maintained in solution and that there is no evidence for the imine tautomer.

New classes of a,b-unsaturated caprolactams containing variable heteroatoms in d-position were synthesized from heterocyclic imines as a starting material. The synthetic route is based on an acid chloride addition followed by a ring-closing metathesis using a ruthenium catalyst.

The product of the Asinger reaction between elemental sulfur, n-butylamine and acetophenone is 8-(nbutylaminophenylmethyliden)-1,2,3,4,5,6,7-heptathiocane which contains a CS 7 ring. A combination of infrared, Raman and inelastic neutron scattering spectroscopies with periodic density functional theory calculations is used to provide a complete assignment of the vibrational spectra of this unusual species. The similarity between the Raman spectra of the compound and that of elemental sulfur is particularly striking.

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