A cross-linked polystyrene supported hindered lithium amide as a deprotonation reagent for α-methylation of lactic acid

The poly(tetramethylglycolide) [PTMG] is currently attracting a lot of interest as an upgraded feedstock recyclable material derived from poly(l-lactic acid). To achieve more efficient process of PTMG production from lactic acid, hindered lithium amide supported by cross-linked polystyrene as a deprotonation reagent was prepared from commercially available Merrifield resin, 2,2,6,6-tetramethyl-4-pipedinol, and n-butyllithium. A polymer-supported lithium 2,2,6,6-tetramethylpiperidide/methyl iodide system was found to be an efficient condition for the α-methylation reaction of lactic acid derivatives, giving excellent yields of α-methylated products (98%) under room temperature for a very short reaction time.