The ‘inverse electron-demand’ Diels–Alder reaction in polymer synthesis. Part 2. Some bis(1,2,4-triazines) as potential bis-diene monomers

Synthetic approaches to a series of 5, 5′-linked bis(l,2,4-triazines) are described: these are potential monomers in Diels–Alder polymerisation processes.Oxidation of bis(α-bromophenylacetyl) substituted aromatic compounds with dimethyl sulfoxide, or (better) oxidation of diacetyl- or bis-(phenylacetyl) substituted aromatic compounds with hydrogen bromide in dimethyl sulfoxide, gives the corresponding bis(l,2-diketones) and bis(α-keto aldehydes); these are converted into 3, 3′-bis(methylsulfanyl)-5, 5′-arylenebis(l,2,4-triazines) by reaction withS-methylthio-semicarbazide. The methylsulfanyl groups may then be oxidised by standard methods to give the corresponding methylsulfinyl or methylsulfonyl compounds, although the oxidised products show a tendency to decompose on storage.