One-pot three-component highly diastereoselective synthesis of isoindolin-1-one-3-phosphonates under solvent and catalyst free-conditions

The one-pot three-component reaction of 2-formylbenzoic acid with (S)- and (R)-methylbenzylamine and dimethyl phosphite (Kabachnik-Fields reaction) proceeded in short reaction times under solvent and catalyst free-conditions to afford the corresponding (3R,1′S)- and (3S,1′R)-isoindolin-1-one-3- phosphonates 3, respectively, in good yield and with high diastereoselectivity (95:5 dr). The use of a solvent decreases the diastereoselectivity and slows the reaction rate. The reaction rate was also influenced by CO2H functionality through protonation of the imine intermediate. The absolute configuration at the new stereogenic center was determined by X-ray crystal analysis, and a mechanism was proposed to explain the high diastereoselectivity. © 2011 Elsevier Ltd. All rights reserved.
The authors thank the CONACYT of Mexico, for their financial support via projects 62271 and J000.400/2009), Ministerio de Ciencia e Innovación (project CTQ2010-17436) and Consejo Superior de Investigaciones Científicas (project 2008MX0044. One of us, J.L.V.C. also thanks the CONACYT for a Graduate Scholarship.