CeCl3-Mediated Addition of Grignard Reagents to 1,3-Diketones

✍ Scribed by Prof. Dr. Giuseppe Bartoli; Dr. Enrico Marcantoni; Prof. Dr. Marino Petrini

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 255 KB
• Volume: 32
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.199310611

✦ Synopsis

Diketones have been always perceived as a practical source of stabilized carbanions owing to the enhanced acidity of the active methylene hydrogen atoms.['] The alkylation of 1,3-diketones can be carried out with almost complete regio-and stereocontrol of the products.121 Every attempt at attacking the carbonyl group with organometallic species led to unsatisfactory results, since these nucleophilic reagents are basic enough to promptly deprotonate the active methylene hydrogen atoms. The resulting enolate anion has an extremely stable cyclic structure with pseudoaromatic character and hence it is completely inert towards nucleophilic attack.[31

We report here that Grignard reagents can be directly added to 1,3-diketones in the presence of dry CeCI, (Scheme 1). Through the addition of the diketone to a sus-

Scheme 1. Synthesis of B-hydroxyketones 2a-h. la.