Enantioselective organocatalytic formal [3 + 3]-cycloaddition of alpha,beta-unsaturated aldehydes and application to the asymmetric synthesis of (-)-isopulegol hydrate and (-)-cubebaol.
[reaction: see text] The first highly enantioselective organocatalyzed carbo [3 + 3] cascade cycloaddition of alpha,beta-unsaturated aldehydes is reported. Using this methodology, crotonaldehyde is converted to 6-hydroxy-4-methylcyclohex-1-enecarbaldehyde, which is used in the synthesis of (-)-isopulegol hydrate, (-)-cubebaol, and p-tolualdehyde as well as (-)-6-hydroxy-4-methyl-1-cyclohexene-1-methanol acetate, an intermediate in the total synthesis of lycopodium alkaloid magellanine. Other alpha,beta-unsaturated aldehydes give rise to chiral cyclohexadienes via formal [4 + 2] reactions.
Hong
Bor-Cherng
BC
Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, Taiwan, ROC. chebch@ccu.edu.tw
Wu
Ming-Fun
MF
Tseng
Hsing-Chang
HC
Liao
Ju-Hsiou
JH
D000447:Aldehydes / Q000737:chemistry*; D000470:Alkaloids / Q000096:biosynthesis; D002384:Catalysis; D003500:Cyclization; D000081005:Cyclohexane Monoterpenes; D032502:Lycopodium / Q000737:chemistry; D015394:Molecular Structure; D011392:Proline / Q000031:analogs & derivatives / Q000737:chemistry*; D013237:Stereoisomerism; D013729:Terpenes / Q000138:chemical synthesis* / Q000737:chemistry
D000447:Aldehydes; D000470:Alkaloids; D000081005:Cyclohexane Monoterpenes; D013729:Terpenes; C409816:isopulegol; D011392:Proline; C012796:2-butenal