Facile alcoholysis of l-lactide catalysed by Group 1 and 2 metal complexes

Abstract

The application of simple metal amides MN(SiMe3)2as effective catalysts for the alcoholysis of cyclic esters are demonstrated. Excess dry methanol and L-lactide were added to a Schlenk flask at room temperature (RT) 1 mol% of MN(SiMe3)2, where M = Li, Na or K was added. A blank test was also performed where no catalyst was added giving no reaction. The conversion of M = Li, 45% to methyl (S,S)-lactyllactatewas obtained in 10 minutes at room temperature. Similar behaviors were observed for m = Na and K, where the reactions decelerated after 20 and 30 minutes. The application also extended to other cyclic esters such as capralactone where the ring-opening product was obtained rapidly in quantitative yield.