Development of a novel benzyl mercaptan as a recyclable odorless substitute of hydrogen sulfide

Article abstract of DOI:10.1055/s-2007-984524

2,4,6-Trimethoxybenzyl mercaptan (4) was developed as an odorless substitute of hydrogen sulfide to afford β-mercapto carbonyl compounds in a Michael addition and to convert alkyl bromides into alkanethiols. Detrimethoxybenzylation of the Michael adducts prepared from 4 and α,β-unsaturated esters or ketones was facilely carried out by treatment with a solvent mixture of trifluoroacetic acid and toluene to give β-mercapto carbonyl compounds. Successive alkaline hydrolysis of 2,4,6-trimethoxybenzyl isothiouronium salt, which was obtained as a side product, regenerated 4 accompanying disulfide 8 in good yield. The disulfide 8 was also converted into 4 by reduction with LiAlH₄. A similar protocol was applicable to the synthesis of alkanethiols using the S _N2 reaction of alkyl bromides. Our method could be complementary to the classical method of using malodorous benzyl mercaptan as a nucleophile and Birch reduction for debenzylation. Georg Thieme Verlag Stuttgart.