Palladium-catalysed C–C coupling reactions in the enantioselective synthesis of 2,4-disubstituted 4,5-dehydropiperidines using galactosylamine as a stereodifferentiating auxiliary
摘要:
Stereoselective synthesis of enantiomerically pure 2,4-disubstituted piperidine derivatives, which are considered interesting pharmacophoric structures, was achieved starting with a tandem Mannich-Michael reaction sequence on O-pivaloylated N-galactosyl aldimines. Subsequent conversion of the thus formed 2-substituted dehydropiperidinones into the corresponding enol tri-flates was carried out by conjugate hydride addition and trapping the enolate with N,N-bis(trifluoromethanesulfonyl)aniline. Their Suzuki-Miyaura coupling with aryl and heteroaryl boronic acids was performed under, conditions compatible with the carbohydrate structure, in particular, with the sensitive N-glycosidic bond. (C) 2004 Elsevier Ltd. All rights reserved.
Palladium-catalysed C–C coupling reactions in the enantioselective synthesis of 2,4-disubstituted 4,5-dehydropiperidines using galactosylamine as a stereodifferentiating auxiliary
摘要:
Stereoselective synthesis of enantiomerically pure 2,4-disubstituted piperidine derivatives, which are considered interesting pharmacophoric structures, was achieved starting with a tandem Mannich-Michael reaction sequence on O-pivaloylated N-galactosyl aldimines. Subsequent conversion of the thus formed 2-substituted dehydropiperidinones into the corresponding enol tri-flates was carried out by conjugate hydride addition and trapping the enolate with N,N-bis(trifluoromethanesulfonyl)aniline. Their Suzuki-Miyaura coupling with aryl and heteroaryl boronic acids was performed under, conditions compatible with the carbohydrate structure, in particular, with the sensitive N-glycosidic bond. (C) 2004 Elsevier Ltd. All rights reserved.