Tetramethyl Thiourea/Co₂(CO)₈-Catalyzed Pauson−Khand Reaction under Balloon Pressure of CO

Abstract

A Pauson-Khand type of conversion of enynes to bicyclic cyclopentenones employing the commercially available Co2(CO)8 and tetramethylthiourea (TMTU) as catalysts is described. This method allows a variety of enynes with diverse functional groups to be cyclized into cyclopentenones of interest. [reaction: see text]

The Renaissance of α‐Methylene‐γ‐butyrolactones: New Synthetic Approaches

“…[104] A [Co 2 (CO) 8 ]/thiourea-catalyzed carbonylative Pauson-Khand reaction of enynes was described more recently by Chen, Yang, and co-workers in which tetrasubstituted a-alkylidene-g-butyrolactones were formed in good yield. [105] A tungsten-promoted intramolecular alkoxycarbonylation approach to a-methylene-g-butyrolactones was reported by Liu and co-workers (Scheme 36). [106] Treatment of propargyl chloride 163 with Na[CpW(CO) 3 ], followed by protonation under controlled conditions, gave the isolable h 3 -glactone 164 in 81 % yield (syn/anti 62:38).…”

Transition metals in organic synthesis: Highlights for the year 2005

“…TEMPO [990] and dodecyl methyl sulfide [991] were shown to promote Pauson-Khand reactions. A catalyst system of dicobalt octacarbonyl-tetramethylthiourea and carbon monoxide was reported [992] and used in synthesis toward micrandilactone [993]. Palladium catalyzed Pauson-Khand reactions using tetramethylthiourea and carbon monoxide [994].…”

Diastereoselective Total Synthesis of (±)‐Schindilactone A

“…The key steps are 1) thiourea/palladium-catalyzed carbonylative annulation cascade [6,7] to construct the GH ring system; 2) a thiourea/cobalt-catalyzed Pauson-Khand reaction (PKR) [8] to form the F ring; 3) a ring-closing metathesis (RCM) reaction to make the cyclooctanoid-based ketal of the DE core;…”

“…[25] Thus, under the optimized PKR conditions, 17 was treated with the complex of tetramethyl thiourea (TMTU) and [Co 2 (CO) 8 ] in dry benzene using a balloon of CO at 70 8C for 4 hours, and the desired product 18 was obtained in 74 % yield with the desired stereochemistry at C13 and C14.…”