Synthesis of Di-, Tri-, and tetrasulfides through multifold carbon-sulfur cross-coupling reactions with indium tri(organothiolates) in a one-pot procedure

摘要

Pd-catalyzed multifold (2-, 3-, and 4-fold) carbon-sulfur cross-coupling reaction of indium tri(organothiolates) with polybromonated aromatic and heteroaromatic compounds was developed in a one-pot procedure. Both 2,5-dibromopyridine and 2,6-dibromopyridine reacted with indium tri(organothiolates) (0.68 equiv) in the presence of 4 mol % of Pd(OAc) 2, 4.2 mol % of Xantphos, and 1 equiv of diisopropylethylamine (DIPEA), producing disulfides in good to excellent yields. These results indicate that indium tri(organothiolates) transfer all three alkylor arylthio groups attached to indium metal to electrophilic coupling partners. Indium tri- (organothiolates) derived from alkyl thiol having a low boiling point, such as n-propyl, isopropyl, and tert-butyl thiol, acted as good nucleophilic coupling partners. In addition, indium tri- (arylthiolates) derived from aryl thiols possessing an electron-withdrawing or -donating group on the aromatic ring participated well in the Pd-catalyzed multifold carbon-sulfur cross-coupling reaction. 4,40-Dibromo-1,10-biphenyl, 9,10-dibromoanthracene, 2,4-dibromoanisole, 2,7-dibromo- 9,9-dimethylfluorene, 3,4-dibromothiophene, 2,3-dibromothiophene, 2,20-bithiophene, 1,3,5-tribromobenzene, and 1,2,4,5-tetrabromobenzene were converted smoothly to the corresponding di-, tri-, and tetrasulfides.