Regio- and stereoselective palladium-catalyzed functionalizations of dienes. Synthesis of (±)-sativene

✍ Scribed by Thomas Antonsson; Christer Malmberg; Christina Moberg

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 144 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)82243-1

✦ Synopsis

Palladium-catalyzed telomerization of IJ-butadiene and N,N-dimethylallylamine and palladiumcatalyzed oxidative cyclization of a 1,5-diene unit constitute the key steps in a new regio-and stereoselective synthesis of the sativene precursor 4. In a recently reported synthesis of the sesquiterpene (f)-sativene (1) starting from 3-methoxy-2cyclopentenone, the txicyclic system was constructed by an internal Diels-Alder reaction of the trimethylsilyl enol ether of methyl (E)-5-(2-methyl-4-oxo-2-cyclopentenyl)-2-pentenoate (2) to give keto ester 3.l This ester was reduced in three steps to keto alcohol 4, which in turn was transformed in nine steps to 1. The dienophile moiety of 2 was obtained by a Wadsworth-Emmons reaction resulting in a 4: 1 mixture of the E and Z isomers, necessitating chromatographic separation. Herein is reported a new regio-and stereoselective synthesis of the crucial intermediate 4 from inexpensive and readily available starting materials.