Preparation of cyclic and acyclic thioethers via hexacarbonyldicobalt alkyne complexes

Demetallation of [Co2{mu-C2(CH2SCH2CH2)2S}(CO)6] with trimethylamine N-oxide affords 1,4,7-trithiacycloundec-9-yne, while similar treatment of [Co2(CO)6{mu-(CCH2SCH2CH2SCH2CH2SCH2C)2}Co2(Co)6] affords 1,4,7,12,15,18-hexathiacyclodocos-9,2-diyne. 20-diyne. A single crystal X-ray diffraction study and H-1 NMR spectroscopy have confirmed that 1,4,7-trithiacycloundec-9-yne adopts an exodentate conformation in the solid and solution states. Trimethylamine N-oxide promoted Pauson-Khand reactions of [Co2(mu-R1C = CCH2SR2)(CO)6] (R1 = H, R2 = Et; R1 = Me, R2 = Et) or [Co2(mu-RSCH2=CCH2SR)(CO)6] (R = Et; R-R = CH2CH2, CH2CH2CH2 or CH2CH2SCH2CH2) with norbornene or of [Co2(mu-R1C=CCH2SR2)(CO)6] (R1 = H, R2 = Et; R1 = Me, R2 = Et) with norbornadiene afford a range of cyclopentenone products, which have been characterised by NMR, IR and mass spectroscopy.