Asymmetric synthesis of pent-3-yl (R)-6-methyl-cyclohex-1-ene carboxylate
Garrido NM., Díez D., Domínguez SH., García M., Sánchez MR., Davies SG.
An expeditious asymmetric synthesis of pent-3-yl (R)-6-methyl-cyclohex-1-enecarboxylate has been achieved in four steps in 42% overall yield employing as the key step a domino reaction initiated by a highly diastereoselective lithium amide 1,4-conjugate addition to a nona-2,7-diendioic diester followed by a 6-exo-trig cyclisation of the thus formed enolate. Cope elimination protocol of the cyclic adduct affords, depending on the lithium amide used, the corresponding nitro-compound or the expected cyclohexene derivative. The methyl group attached to the cyclohexane ring is achieved by selective ester hydrolysis and subsequent Barton decarboxylation. © 2006 Elsevier Ltd. All rights reserved.