Approaches to bridged thia[17]annulenes

Abstract

The macrocyclic trisulphide (5) has been prepared from 2,5-bis-(p-bromomethylphenylmethylthiomethyl)thiophen (7) but attempts to convert it into the triolefin (2)via a Stevens rearrangement of the derived trimethylsulphonium salt and elimination of sulphur were frustrated by the intractability of the salt. In other experiments 15,17-dimethyl-16-thiabicyclo[12.3.0]heptadeca-2,12,14,17-tetraen-6,8-diyne (9) was prepared but attempted base-catalysed rearrangement to the bridged this-annulene 15,17-dimethyl-16-thiabicyclo[12.3.0] heptadeca-2,4,6,8,10,12,14,17octaene (8) led to a product of uncertain structure.