RESUMO
[reaction: see text] Intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar derivatives with one to four free hydroxyl group(s) is reported. The INOC reaction, using chloramine-T, in the presence of silica gel, to generate nitrile oxides from oximes, proceeded smoothly to afford five- or six-membered carbocycles in good to excellent yields. This new methodology alleviates protection/deprotection steps and makes the synthetic route shorter and more efficient.
Assuntos
Alcenos/química , Carboidratos/química , Nitrilas/química , Cloraminas/química , Ciclização , Hidroxilação , Lactonas/química , Estrutura Molecular , Oximas/química , Sílica Gel , Dióxido de Silício/química , Compostos de Tosil/químicaRESUMO
First syntheses of C6,7 and C7 enantiopure cocaine analogues were achieved from D-(-)-ribose via a trans-acetonide controlled endo-selective intramolecular nitrone-alkene cycloaddition (INAC) as the key step. This synthetic scheme allows practical preparation of cocaine analogues for bioevaluation as potential candidates for the treatment of cocaine addiction and as potential conjugates for immunotherapy.
Assuntos
Cocaína/análogos & derivados , Cocaína/síntese química , Ribose/química , Catálise , Cocaína/química , Transtornos Relacionados ao Uso de Cocaína/tratamento farmacológico , Estrutura Molecular , EstereoisomerismoRESUMO
Exploitation of silica gel/chloramine T mediated intramolecular nitrile oxide-alkene cycloaddition (INOC) of sugar-derived oximes to carbocycles furnished the first synthesis of gabosine F from l-arabinose in 12 steps with 23% overall yield, thereby confirming its absolute configuration. Similarly, efficient syntheses of gabosine O and 4-epi-gabosine O were accomplished from D-mannose in 9 and 11 steps with 41% and 38% overall yields, respectively, involving INOC, regioselective dehydration, and diastereoselective hydrogenation as the key steps.