RESUMO
The reaction of enone 1, bearing an internal nucleophilic moiety, i.e., furan or pyrrole (X = O, NR'), with isocyanides is presented. The formation of products resulting from the reaction of the zwitterionic intermediate 2 with a second equivalent of isocyanide prior to cyclization to give 3, as well as the direct formation of 4 from 2, is described.
Assuntos
Cianetos/química , Compostos Heterocíclicos com 3 Anéis/síntese química , Cetonas/química , Estrutura MolecularRESUMO
[reaction: see text] The stereoselective aldol reaction of 3-silyloxyfurans with aldehydes in the presence of a Lewis acid is described. N-Bromosuccinimide (NBS)-mediated cyclization of the aldol product leads to the formation of the 2,7-dioxa-bicyclo[2.2.1]heptan-3-one ring system, which represents the formal product of hetero Diels-Alder reaction of the furan with the aldehyde.
Assuntos
Furanos/química , Aldeídos/química , Bromosuccinimida , Cristalografia por Raios X , Ciclização , EstereoisomerismoRESUMO
[reaction: see text] The synthesis of stereochemically defined tri- and penta-heterocyclic ring systems 9 and 28, respectively, via the metathesis reaction of substituted oxanorbornanes derived from 3 is described.