Titanocene-catalysed, selective reduction of ketones in aqueous media. A safe, mild, inexpensive procedure for the synthesis of secondary alcohols via radical chemistry

✍ Scribed by Alejandro F. Barrero; Antonio Rosales; Juan M. Cuerva; Andreas Gansäuer; J.Enrique Oltra

• Book ID: 104252785
• Publisher: Elsevier Science
• Year: 2003
• Tongue: French
• Weight: 198 KB
• Volume: 44
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(02)02703-x

✦ Synopsis

We report here a novel procedure for the reduction of ketones to secondary alcohols using catalytic quantities of commercially available Cp 2 TiCl 2 , inexpensive Zn dust and water as proton source. Mechanistically the reaction presumably proceeds via titanoxy radicals. In practice this reduction process has significant advantages: it shows an interesting selectivity pattern, takes place under mild conditions using safe, cheap reagents and does not require anhydrous solvents. The proton-donor activity of water under these conditions avoids the use of the frequently poisonous hydrogen-atom donors generally required to reduce free radicals. This procedure is also highly convenient for synthesising deuterium-labelled alcohols employing relatively inexpensive D 2 O as deuterium source.