Novas abordagens na síntese de heterociclos com potencial aplicação na síntese de moléculas bioativas
Resumo
Cobalt-catalyzed oxidative cyclization of gem-disubstituted
conjugated alkenols: In this part of the work we applied the Mukaiyama
Oxidative Ciclization under oxidative and reduced termination conditions
aiming the preparation of trisubstituted 2,5,5-THFs-trans from gemdisubstituted
aromatic conjugated olefins with different electronic
properties. The THFs were obtained only under reduced termination
conditions, with of 32-44% of yields. Under oxidative termination
conditions, only products from secondary radical reactions that competed
with the oxidative cyclization reaction were observed. In addition, the
diastereoselectivity involved in this process was evaluated,, which in this
case were obtained in 17-46% of yields and dr 2.5:1 to 5.4: 1.
Preparation of 1H-1,2,3-triazole under more sustainable conditions: In
this second part of the work the main objective was to develop an one-pot
methodology for the preparation of 1H-1,2,3-triazoles from nitrolefins. This
methodology is inserted in a concept of a more sustainable chemistry,
since the obtaining heterocyclics was carried out through a metal-free
approach, using the green solvent PEG400, and the direct use of sodium
azide. The 1H-1,2,3-triazoles were obtained via one-pot reaction in good
yields (54-80%).