Efficient tin hydride-mediated radical cyclisation of secondary amides leading to substituted pyrrolidinones. Part 2. Application to the synthesis ofaromatic kainic acid analogues

An enantioselective synthesis of phenyl allokainoid, starting from D-serine , is reported. Tin-mediated cyclisation of a secondary amide was used in th e key step to produce a trisubstituted pyrrolidinone in excellent yield (ca . 80%). The predominant formation of the all-trans diastereoisomer is consi stent with a reversible cyclisation to give the thermodynamically more stab le product.