Lithium aluminium amide [LiAI（NHR）4] 5 obtained by treating the primary amine 4 with LiAlH4 could promote the ring opening of epoxide 2 and led to high regioselective product of racemic bis[2-（6-fluoro-2-chromanyl...Lithium aluminium amide [LiAI（NHR）4] 5 obtained by treating the primary amine 4 with LiAlH4 could promote the ring opening of epoxide 2 and led to high regioselective product of racemic bis[2-（6-fluoro-2-chromanyl）-2-hydroxyethyl]amine methanesulfonic acid salt 7.展开更多
A novel and concise synthetic access to enantiopure chiral 2-aryl/alkyl substituted 4-piperidone has been demonstrated.This new route features two key steps:the highly diastereoselective conjugate addition of homochir...A novel and concise synthetic access to enantiopure chiral 2-aryl/alkyl substituted 4-piperidone has been demonstrated.This new route features two key steps:the highly diastereoselective conjugate addition of homochiral lithium amides to trans-β-substituted-α,β-unsaturated methyl esters guaranteed the enantiopurity at 2 position(de>19:1)and the intramolecular attacking of carbanions to methyl esters led to the formation of the piperidone ring.A wide range of substrates,including chiral2-aryl and 2-alkyl-4-piperidones,were successfully synthesized with modest to high yield.Moreover,some non-chiral3-substituted-4-piperidones were also synthesized with enhanced ring-formation yield,implicating the versatility of this method in construction of various piperidine rings.展开更多
基金the National 863 Program(No.2003AA323030)the National Natural Science Foundation of China(No.50272069 and No.20472090)for financial support.
文摘Lithium aluminium amide [LiAI（NHR）4] 5 obtained by treating the primary amine 4 with LiAlH4 could promote the ring opening of epoxide 2 and led to high regioselective product of racemic bis[2-（6-fluoro-2-chromanyl）-2-hydroxyethyl]amine methanesulfonic acid salt 7.
基金CAS Key Laboratory of Synthetic Chemistry of Natural Substances (2008DP173071) for analysis support
文摘A novel and concise synthetic access to enantiopure chiral 2-aryl/alkyl substituted 4-piperidone has been demonstrated.This new route features two key steps:the highly diastereoselective conjugate addition of homochiral lithium amides to trans-β-substituted-α,β-unsaturated methyl esters guaranteed the enantiopurity at 2 position(de>19:1)and the intramolecular attacking of carbanions to methyl esters led to the formation of the piperidone ring.A wide range of substrates,including chiral2-aryl and 2-alkyl-4-piperidones,were successfully synthesized with modest to high yield.Moreover,some non-chiral3-substituted-4-piperidones were also synthesized with enhanced ring-formation yield,implicating the versatility of this method in construction of various piperidine rings.
