Treatment of serine-derived N-(α-haloacetamido)dehydroalanine derivatives with tributyltin hydride in boiling benzene or toluene afforded pyroglutamates in 47–84% yield. The radicalcyclisation reaction, which proceeded regioselectively in a disfavoured 5-endo-trig manner, was found to be most efficient when dichloro- and trichloroamides were employed as starting materials.
New route to pyroglutamates viaα-chloro amide radical cyclisation
作者:Karen Goodall、Andrew F. Parsons
DOI:10.1039/p19940003257
日期:——
The tributyltin hydride mediated radicalCyclisation of N-(α-chloroacetamido)dehydroalanine derivatives prepared from serine proceeds regioselectively to give pyroglutamates in 47–74% yield– the cyclisation of the intermediate carbamoylmethyl radical proceeds in a ‘disfavoured’ 5-endo-trig manner.