Gold-catalyzed homo- and cross-annulation of alkynyl carboxylic acids: a facile access to substituted 4-hydroxy 2-pyrones and total synthesis of pseudopyronine A

• Published in: Organic & biomolecular chemistry 2020-11, Vol.18 (42), p.8716-8723
• Main Authors: Gayyur, Choudhary, Shivani, Saxena, Anchal, Ghosh, Nayan
• Format: Article
• Language: English
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/d0ob01700k

A Au( i )-catalyzed homo- and cross-annulation reaction of alkynyl carboxylic acids offering 3,6-disubstituted 4-hydroxy 2 H -pyrones has been demonstrated. The reaction tolerates various substituted alkynyl carboxylic acids and moderate to good yields of α-pyrone scaffolds have been observed. Later, a gram-scale reaction of the acid and the total synthesis of the natural product pseudopyronine A have been carried out successfully. A single-step protocol for the synthesis of 3,6-disubstituted 4-hydroxy 2 H -pyrones under goldcatalyzed conditions is developed from alkynyl acids. The total synthesis of pseudopyronine A is achieved with an overall 24% yield.