Catalytic Intermolecular Pauson – Khand Reactions in Supercritical Ethylene

✍ Scribed by Nakcheol Jeong; Sung Hee Hwang

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 89 KB
• Volume: 39
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/(sici)1521-3773(20000204)39:3<636::aid-anie636>3.0.co;2-s

✦ Synopsis

Supercritical fluids are rapidly becoming alternative reaction media for conventional organic reactions. The advantages of reactions in supercritical fluids include the high solubility of gaseous reactants, rapid diffusion of solutes, and weakening of the solvation around the reacting species. In addition, these fluids are easily recycled and allow the separation of the dissolved compounds by selective precipitation, which implicates possibilities in the development of environmentally benign processes. Sequential precipitation of the product and catalyst is possible by a gradual release of pressure. Recent progress has shown that supercritical fluids can substitute conventional organic solvents in various transition metal catalyzed transformations. [3] We demonstrated that catalytic intra-and intermolecular Pauson ± Khand reactions could be carried out in supercritical CO 2 with high efficiency (Scheme 1). We report here a new dimension of this EtO 2 C EtO 2 C O EtO 2 C EtO 2 C [Co 2 (CO) 8 ], CO (30 atm) sc CO 2 , 198 atm 90 o C, 24 h 82 % Scheme 1. Example for a Pauson ± Khand reaction in supercritical (sc) CO 2 .