Catalytic Macrocyclization of 3,3-Dimethylthietane by Re2(CO)9(SCH2CMe2CH2)

The reaction of Re2(CO)9(NCMe), 1, with 3,3-dimethylthietane (SCH2CMe2CH2, 3,3-DMT) yielded the complex Re2(CO)9(SCH2CMe2CH2), 2. Compound 2 has been found to react with 3,3-DMT at 100 °C to yield the polythioether macrocycles 3,3,7,7,11,11-hexamethyl-1,5,9-trithiacyclododecane, 3 (Me612S3), 3,3,7,7,11,11,15,15-octamethyl-1,5,9,13-tetrathiacyclohexadecane, 4 (Me816S4), and 3,3,7,7,11,11,15,15,19,19-decamethyl-1,5,9,13,17-pentathiacycloeicosane, 5 (Me1020S5), catalytically, but the activity and yields of the macrocycles are low. High molecular weight oligomers of 3,3-DMT are the principal products. A macrocyclization mechanism consisting of a metal-induced ring-opening cyclooligomerization of three, four, and five molecules of 3,3-DMT, respectively, is proposed. The reaction of 3 with CpMn(CO)3 in the presence of UV irradiation yielded the complex CpMn(CO)2(η1-Me612S3), 6. The molecular structures of each of the macrocycles 3, 4, and 5 and the complexes 2 and 6 were determined by single-crystal X-ray diffraction analyses.