Green synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran and itssubsequent enantioselective epoxidation
ABSTRACT: tThe clean synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran epoxide starting from 3-methyl-2-butenal is reported using recyclable catalysts. H4PMo11VO40(PMo11V) and (PyH)3HPMo11VO40(Py3–PMo11V) Keggin-type heteropolyacids were used to synthesize 6-cyano-2,2-dimethyl-2-H-1-benzopyran in t...
| Autores: | , , , , , |
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| Tipo de documento: | artigo |
| Estado: | Versão publicada |
| Data de publicação: | 2015 |
| País: | Colombia |
| Recursos: | Universidad de Antioquia |
| Repositório: | Repositorio UdeA |
| Idioma: | inglês |
| OAI Identifier: | oai:bibliotecadigital.udea.edu.co:10495/13117 |
| Acesso em linha: | http://hdl.handle.net/10495/13117 http://dx.doi.org/10.1016/j.molcata.2014.11.027 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Síntesis verde Epoxidación enantioselectiva |
| Resumo: | ABSTRACT: tThe clean synthesis of 6-cyano-2,2-dimethyl-2-H-1-benzopyran epoxide starting from 3-methyl-2-butenal is reported using recyclable catalysts. H4PMo11VO40(PMo11V) and (PyH)3HPMo11VO40(Py3–PMo11V) Keggin-type heteropolyacids were used to synthesize 6-cyano-2,2-dimethyl-2-H-1-benzopyran in two steps with 35% yield. This is an alternative procedure to the traditionalmethodology with pyridine or picoline as catalyst, where 6-cyano-2,2-dimethyl-2-H-1-benzopyran isobtained by condensation of 4-cyanophenol with 1,1-diethoxy-3-methyl-2-butene. The 6-cyano-2,2-dimethyl-2-H-1-benzopyran epoxide was obtained using Jacobsen-type catalysts, and in situ generateddimethyldioxirane (DMD) as oxidizing agent, that in comparison to m-CPBA/4-NMO and NaOCl/4-PPNOdid not degrade the catalyst. In presence of 4-phenylpyridine N-oxide (4-PPNO) at 4◦C, enantioselectiv-ities of 87% for 3S,4S-epoxide and 68% for 3R,4R-epoxide were obtained with the S,S- and R,R-Jacobsencatalysts, respectively. Overall yield was approximately 17% for 3S,4S-epoxide. |
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