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

Abstract

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.

A New Route to Polyselenoether Macrocycles. Catalytic Macrocyclization of 3,3-Dimethylselenetane by Re2(CO)9SeCH2CMe2CH2

“…Although the isolated yields are very low for 2 and 4 , for 3 the yield is equivalent to 16.5 turnovers or 2 turnovers/h. This is about 70 times more active than 7 is for the catalytic formation of the sulfur homologue Me 6 12S3 from DMT 3c…”

“…Interest in the ligand properties of polythioether macrocycles continues to develop , Third-row transition-metal carbonyl complexes have proven to be the most effective catalysts for these reactions. Polyselenoether macrocycles also have a good potential to serve as ligands for the transition metals, but the number of known polyselenoether macrocycles is very small 4 and investigations of their ligand properties are even fewer …”

Alkyl 2-Benzothiazolyl Sulfide Ligated Dirhenium Complexes: Syntheses, Structure and Computational Study of [Re2(CO)8{μ,η1,η1-(R)SCNSC6H4}] (R = CH3 and C2H5)

“…The rhenium-rhenium bond distance of 2.9735(2) Å and 2.9925(3) Å in compounds 1 and 2, respectively, clearly corresponds to a rhenium-rhenium single bond, which is in accordance with the 18-electron count for each metal atom. The rhenium-rhenium single bond distances in compounds 1 and 2 are shorter than the reported dirhenium compounds [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. The ligation of 2-(alkylthio)benzothiazole to the dirhenium core through the nitrogen and sulfur atoms of the ligand results a five-membered metallacycle which does not allow the rheniumrhenium bond to relax, and hence a significant shortening of the rhenium-rhenium bond in 1.…”

Recent Development of Rhenium-Catalyzed Organic Synthesis

“…Re 2 ( C O ) 9 (NCMe) was also demonstrated to be the efficient catalyst for the cyclooligomerization of β − propiothiolactone at room temperature to develop a convenient route to polythiolactone macrocycles (Scheme 48) [72]. Other sulfur-coordinated dirhenium carbonyl complexes from the reaction of R e 2 ( C O ) 9 (NCMe) with 3-methylthietane [73] and 3,3-dimethylthietane [74] show similar catalytic activity for the cyclooligomerization of 3-methylthietane and 3,3-dimethylthietane, respectively. Furthermore, they disclosed that the polyselenoether macrocycles could be obtained by the similar ring-opening cyclooligomerization of 3,3-dimethylselenatane at 115 o C catalyzed by Re 2 (CO) 9 (SeCH 2 CMe 2 CH 2 ) [75].…”