A General Synthesis of Bis-α-acyloxy-1,4- and -1,5-diketones Through Catalytic Oxidative Opening of Acylated THF and THP Diols

• Published in: European journal of organic chemistry 2013-03, Vol.2013 (9), p.1781-1789
• Main Authors: Piccialli, Vincenzo, D'Errico, Stefano, Borbone, Nicola, Oliviero, Giorgia, Centore, Roberto, Zaccaria, Sabrina
• Format: Article
• Language: English
• Subjects: Cyclization; Nitrogen ­heterocycles; Oxidation; Oxygen heterocycles; Ring-opening; Synthetic methods
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201201554

The first general synthesis of bis‐α‐acyloxy‐1,4‐ and ‐1,5‐diketones has been accomplished in a catalytic oxidative opening of bis‐acylated THF and THP (tetrahydropyran) diols, which were synthesised by osmium‐ or ruthenium‐catalysed oxidative cyclisation of 1,5‐ and 1,6‐dienes. The overall sequence corresponds to the regioselective double ketoacyloxylation of the starting diene. The synthesised bis‐α‐acyloxy‐1,5‐dicarbonyl compounds have been transformed into pyridine‐based oxido pincer ligands or pyrazinedimethanol substances, leading to the discovery of unprecedented aromatisation routes. The first general synthesis of bis‐α‐acyloxy‐1,4‐ and ‐1,5‐diketones is reported. The process features the catalytic oxidative opening of bis‐acylated THF and THP diols, which were synthesised by the transition‐metal‐mediated oxidative cyclisation of 1,5‐ and 1,6‐dienes. The 1,5‐diketone products were cyclised to give pyridinedimethanol derivatives. New aromatisation modes have been disclosed.