Tandem Synthesis of Pyrroloacridones via [3 + 2] Alkyne Annulation/Ring-Opening with Concomitant Intramolecular Aldol Condensation
摘要:
An efficient cascade strategy for the direct synthesis of pyrrolo[3,2,1-de]acridones 4a-v, 5a-h from iodopyranoquinolines 2a-i by the palladium-catalyzed regioselective [3 + 2] alkyne annulation/ring-opening followed by intramolecular aldol condensation under microwave irradiation is described. The chemistry involves the in situ formation of pyrroloquinolines Y, via palladium-catalyzed selective [3 + 2] annulation of iodopyranoquinolines and internal akynes with ring-opening and successive intramolecular cross-aldol condensation. Both the symmetrical and unsymmetrical internal alkynes were reacted smoothly to provide the desired pyrroloacridones in good yields. This methodology provides the facile conversion of easily accessble iodopyranoquinoline into highly functionalized biologically important pyrroloacridones in a single process.
Chemoselective Azidation of <i>o</i>-Alkynylaldehydes over [3 + 2] Cycloaddition and Subsequent Staudinger Reaction: Access to Benzonaphthyridines/Naphthyridines
作者:Pradeep Kumar、Trapti Aggarwal、Akhilesh K. Verma
DOI:10.1021/acs.joc.7b01016
日期:2017.6.16
conditions is described. Mechanisticstudies confirm the formation of azido-pyranoquinolines through nucleophilic attack of azide on pyrilium intermediate over [3 + 2] cycloaddition of the azide on the alkyne. The synthesized azido-pyranoquinolines were transformed into benzonaphthyridines via Staudinger reaction. The mechanistic pathway was supported by deuterium labeling experiment and X-ray crystallographic