Metal-Free, DBU-Mediated, Microwave-Assisted Synthesis of Benzo[c]xanthones by Tandem Reactions of Alkynyl-1,3-diketones

A base-mediated, green, microwave-assisted efficient preparation of a diverse benzoxanthone library from variety of readily accessible gamma-alkynyl 1,3-diketones is reported. The synthesis is based on tandem reactions involving intramolecular cyclization, propargyl-allenyl isomerization, and electrocyclization in one pot. Some of the benzoxanthones are also synthesized by the one-pot reaction of 1,3-diketone and alkynyl bromide under basic heating conditions. This transformation also results in the construction of one new C-C bond and one new C-O bond.

Automated summary

A base-mediated, green, microwave-assisted efficient method for the synthesis of a diverse benzoxanthone library from readily accessible gamma-alkynyl 1,3-diketones was reported in this study. The synthesis involves tandem reactions including intramolecular cyclization, propargyl-allenyl isomerization, and electrocyclization in one pot, resulting in the formation of new C-C and C-O bonds.