Diels-Alder reaction of R-(−)-carvone with isoprene

✍ Scribed by Tony K.M. Shing; Ho Y. Lo; Thomas C.W. Mak

• Book ID: 104209304
• Publisher: Elsevier Science
• Year: 1999
• Tongue: French
• Weight: 346 KB
• Volume: 55
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(99)00145-3

✦ Synopsis

Diels-Alder reactions of R-(-)-carvone with isoprene using different Lewis acids as catalysts have been studied. The best results were obtained with EtAICI2 at 25 °C for 48 hours. The yields are quantitative and the d.e. is 86.8%. Regioselective dihydroxylation at the endocyclic double bond of the cycloadduct followed by acetonation gave a crystalline acetonide, the structure and stereochemistry of which were confirmed by an X-ray crystallographic analysis. Hence the stereochemical outcome of the Diels-Alder reaction is now established and the reaction occurred preponderantly in an anti orientation with respect to the isopropylene group in R-(-)carvone.