family of bicyclic silylether organocatalysts that display some remarkable features. Apart from being extremely stable to hydrolytic conditions and possessing excellent catalytic performances, the rigidity of the bicyclic structure imposes a synclinal endo disposition of the bulky substituents with respect to the pyrrolidine ring, opposed to the more stable synclinal exo conformations of Jørgensen–Hayashi
Enantioselective synthesis of tetrahydrocarbazoles via trienamine catalysis and their anxiolytic-like activity
作者:Tushar Janardan Pawar、Edson E. Maqueda-Cabrera、Angel Josabad Alonso-Castro、José Luis Olivares-Romero、David Cruz Cruz、Clarisa Villegas Gómez
DOI:10.1016/j.bmcl.2020.127063
日期:2020.5
organocatalytic strategy via trienamine activation. The in situ ortho-quinodimethane species, formed by the condensation of the N-protected 2-methylindole acrylaldehyde with a sterically hindred diarylsilylprolinol ether derivative as catalyst, easily participate in a Diels–Alder reaction with the ethyl cyanophenyl acrylate as dienophile, in good yields and excellent stereoselectivity. These compounds showed
providing a facile entry to highly complex molecular frameworks with excellent stereocontrol. For the Diels-Alder reactions with 3-olefinic oxindoles, spirocyclic oxidoles are formed in high yields, and with enantioselectivities in the range of 94-98% ee. It is demonstrated, that some of these products can be transformed into the hexahydrofuro[2,3-b]indole fragment. The organocatalytic trienamine concept