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Gold‐Catalyzed Cyclization of Furan‐Ynes bearing a Propargyl Carbonate Group: Intramolecular Diels–Alder Reaction with In Situ Generated Allenes
Author(s) -
Sun Ning,
Xie Xin,
Chen Haoyi,
Liu Yuanhong
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201603055
Subject(s) - furan , chemistry , propargyl , moiety , aromatization , intramolecular force , cycloaddition , medicinal chemistry , phosphine , catalysis , organic chemistry
Gold‐catalyzed cyclization of various furan‐ynes with a propargyl carbonate or ester moiety results in the formation of a series of polycyclic aromatic ring systems. The reactions can be rationalized through a tandem gold‐catalyzed 3,3‐rearrangement of the propargyl carboxylate moiety in furan‐yne substrates to form an allenic intermediate, which is followed by an intramolecular Diels–Alder reaction of furan and subsequent ring‐opening of the oxa‐bridged cycloadduct. It was found that the steric and electronic properties of phosphine ligands on the gold catalyst had a significant impact on the reaction outcome. In the case of 1,5‐furan‐yne, the cleavage of the oxa‐bridge in the cycloadduct with concomitant 1,2‐migration of the R 1 group occurs to furnish anthracen‐1(2 H )‐ones bearing a quaternary carbon center. For 1,4‐furan‐yne, a facile aromatization of the cycloadduct takes place to give 9‐oxygenated anthracene derivatives.