Asymmetric phase-transfer-catalyzed intramolecular N-alkylation of indoles and pyrroles: a combined experimental and theoretical investigation.
Asymmetric phase-transfer catalysis (PTC) has risen to prominence over the last decade as a straightforward synthetic methodology for the preparation of pharmacologically active compounds in enantiomerically pure form. However, the complex interplay of weak nonbonded interactions (between catalyst and substrate) that could account for the stereoselection in these processes is still unclear, with tentative pictorial mechanistic representations usually proposed. Here we present a full account dealing with the enantioselective phase-transfer-catalyzed intramolecular aza-Michael reaction (IMAMR) of indolyl esters, as a valuable synthetic tool to obtain added-value compounds, such as dihydro-pyrazinoindolinones. A combined computational and experimental investigation has been carried out to elucidate the key mechanistic aspects of this process.
Bandini
Marco
M
Dipartimento di Chimica G. Ciamician, Alma Mater Studiorum-Università di Bologna, via Selmi 2, 40126 Italy. marco.bandini@unibo.it
Bottoni
Andrea
A
Eichholzer
Astrid
A
Miscione
Gian Pietro
GP
Stenta
Marco
M
D000478:Alkylation; D002384:Catalysis; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D008962:Models, Theoretical; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D007211:Indoles; D011758:Pyrroles