A gold(I) autotandem catalysis protocol is reported for the de novo synthesis of densely substituted pyrazolines and dihydropyridines from the corresponding imine derivatives in a highly regioselective fashion via a one-pot aza-enyne metathesis/6π-electrocyclization sequence. The substituents on the nitrogen atom of the imine perfectly control the reaction pathways from the pivotal 1-azabutadiene intermediate;
An efficient solid-phase synthesis of 3-substituted and 3,3-disubstituted 1,2-dialkylpyrazolidine-3,5-diones
作者:Rongjun He、Yulin Lam
DOI:10.1039/b802648c
日期:——
An efficient and regioselective procedure for the synthesis of di-, tri- and fully-substituted pyrazolidine-3,5-diones on a solid-phase format is described. Microwave irradiation provided significant rate enhancement in this protocol. To demonstrate the versatility of this chemistry, a representative set of 25 compounds was prepared.
I<sub>2</sub> mediated synthesis of 5-substituted-3-methyl/benzyl-1,3,4-oxadiazol-2(3H)-ones via sequential condensation/oxidative cyclization and rearrangement
A simple and efficient iodine-assisted protocol for the synthesis of 5-substituted-3-methyl/benzyl-1,3,4-oxadiazol-2(3H)-ones has been developed. The reaction involves a sequential condensation followed by tandem oxidative cyclization and rearrangement of readily available methyl/benzyl carbazates and aldehydes as starting substrates. The presence of iodine and base promotes intramolecular C–O bond