Microwave- and Thermally Promoted Iminyl Radical Cyclizations: A Versatile Method for the Synthesis of Functionalized Pyrrolines.
J Org Chem
; 87(24): 16250-16262, 2022 12 16.
Article
em En
| MEDLINE
| ID: mdl-36472924
ABSTRACT
A detailed study of iminyl radical cyclizations of O-aryloximes tethered to alkenes is reported. The reactions can be triggered by either microwave irradiation or conventional heating in an oil bath. A variety of radical traps can be employed, enabling C-C, C-N, C-O, C-S, or C-X bond formation and producing a diverse array of functionalized pyrrolines. Substrates containing an allylic sulfide furnish terminal alkenes by a tandem cyclization-thiyl radical ß-elimination pathway. Cyclizations of hydroxylated substrates exhibit moderate diastereoselectivity that in some cases can partially be attributed to intramolecular hydrogen bonding. Computational studies suggested a possible role for thermodynamics in controlling the stereochemistry of cyclizations. The reaction temperature can be lowered from 120 to 100 °C by employing O-(p-tert-butylphenyl)oximes instead of O-phenyloximes as substrates, and these second-generation iminyl radical precursors can be used in a one-pot oxime ether formation-cyclization that is promoted by conventional heating. The functionalized pyrrolines obtained from these reactions can be conveniently transformed in several different ways.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Oximas
/
Micro-Ondas
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Estados Unidos