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 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.

• Autores: Sathicqa, Ángel; Vázquez, Patricia; Villa Holguín, Aída Luz; Alarcón Durango, Edwin Alexis; Grajales González, Edwing Javier; Cubillos Lobo, Jairo Antonio
• Tipo de recurso: Article of investigation
• Fecha de publicación: 2015
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/13117
• Acceso en línea: http://hdl.handle.net/10495/13117; http://dx.doi.org/10.1016/j.molcata.2014.11.027
• Palabra clave: Síntesis verde; Epoxidación enantioselectiva
• Rights: openAccess
• License: Atribución-NoComercial-SinDerivadas 2.5 Colombia