Synthesis and NMR spectroscopic studies of allylsulfanyl‐ N 1 ‐alkyl‐ N 4 ‐phenyl‐1,4‐phenylenediamines and their cyclization products, 2,3‐dihydro‐1‐benzothiophenes and thiochromans

Regioselective addition of allylthiol at the C‐3 position adjacent to the nitrogen carrying the phenyl group of the 1,4‐phenylenediamine moiety of compounds 1 – 4 was rigorously confirmed by 1D NOE difference in combination with gHMBC experiments. The structures of 1,4‐phenylenediamines 1 – 4 , allylsulfanyl‐ N 1 ‐alkyl‐ N 4 ‐phenyl‐1,4‐phenylenediamines 5 – 8 and cyclization products 9 – 14 were completely analyzed in both CDCl 3 and DMSO‐ d 6 solutions. The 1 H and 13 C NMR spectra of 10 and 11, which contain two chiral centers, exhibit duplication for several signals, indicating the existence of two diastereomeric forms. The full structures of 5 and 9 were unambiguously confirmed by x‐ray crystallography. The 1 H and 13 C NMR spectra of all compounds were assigned using one‐ and two‐dimensional NMR techniques (APT, DEPT, 1D NOE difference, COSY, NOESY, HETCOR, gHMQC and gHMBC). Copyright © 2004 John Wiley & Sons, Ltd.