NaH Promoted One-Pot Tandem Reactions of 3-(1-Alkynyl) Chromones to Form 2-Nitrogen-Substituted Xanthones.

ABSTRACT: A silver-catalyzed dimerization of ethyl isocyanoacetates could trigger the tandem reaction of 3-(1-alkynyl) chromones under the basic condition in a one-pot reaction to afford xanthone skeletons with 2-imidazolyl substitution in an efficient manner. With the control experiment in hand, a mechanism including dimerization of isocyanoacetate/deprotonation/Michael addition/ring-opening/cyclization 1,2-elimination was deduced. Further investigation for the base was carried out, resulting in NaH as an optimal base to avoid the dimerization of 3-(1-alkynyl) chromones. The scope of this methodology was extended on the different substituents of 3-(1-alkynyl)-chromones and the potential of other N-heterocycle glycine ester anions to give the novel functional 2-nitrogen-derived xanthones.

SUBMITTER: Duan WD 

PROVIDER: S-EPMC7288716 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature