Synthesis and structural analysis of mercaptothiacalix[4]arene

The synthesis of p-tert-butyltetramercaptotetrathiacalix[4]arene 1 bearing eight sulfur atoms was achieved in high overall yield (80%); the synthetic strategy used was based on the synthesis of p-tert-butyltetrathiacalix[4]arene 2, treatment of the latter with N,N-dimethylthiacarbamoyl chloride under mild conditions, thermal transposition of the O-thiacarbamoyl into the S-thiacarbamoyl derivatives in quantitative yield and deprotection of the sulfur centres by treatment with hydrazine hydrate; the conformation of compound 1 was investigated in the solid state by X-ray diffraction on a single crystal, which revealed that compound 1 adopts the 1,3-alternate conformation.