Nagireddy A, Singam MKR, Nanubolu JB, Sridhar Reddy M. Base-Mediated Cyclopentannulation of Ynones with Amino Crotonates for Regio- and Stereoselective Synthesis of Pentafulvenes and Cyclopenta[
c]quinolines.
J Org Chem 2020;
85:6970-6980. [PMID:
32421329 DOI:
10.1021/acs.joc.0c00203]
[Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A regio- and stereoselective synthesis of unsymmetrically substituted pentafulvenes is reported via the condensation of readily available ynones and amino crotonates under very mild conditions. The mechanism of this 3 + 2 annulation involved a vinylogous Michael addition followed by an intramolecular enamine aldol condensation. Substrates with o-bromo tether further cyclized to pentannulated hydroquinolines through an isomerization/SNAr in the same reaction pot at the elevated temperature.
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