- PROCESS FOR THE PREPARATION OF OPTICALLY-ACTIVE COMPOUNDS
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A method of preparing enatiomerically enriched 3a,6,6,9a-tetramethyl-dodecahydro-naphtho[2,1-b]furan, formula (I), from (E,E)- homofarnesic acid or (E)-monocyclohomofarnesic acid by (a) reacting firstly with a chiral alcohol, (b) reacting the product of (a) with an acid to cause a first cyclisation, (c) producing an alcohol by reacting the product of (b) with a reducing agent and (d) causing a second cyclisation by reacting the product of (c) with an acid. The product of this process gives a mixture of both enantiomers with one in excess.
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Page/Page column 11-13
(2008/06/13)
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- Synthesis of Ambrox from labdanolic acid
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A synthesis of the valuable amber-type odorant Ambrox from labdanolic acid (main diterpenoid of the acid fraction of non-polar extracts of Cistus ladaniferus L.) is reported. The conversion is based on (a) the α,β-dehydrogenation of methyl labdanolate using an organoselenium reagent, (b) subsequent oxidative degradations of the side chain, and (c) final acid-promoted cyclization of the resulting tetranorlabdan-8α,12-diol. The influence of the temperature and solvent in the cyclization of the diol with p-toluenesulfonic acid is also described. Thus, Ambrox has been obtained by a six-step procedure in 33% overall yield from methyl labdanolate.
- Castro, Juan M,Salido, Sofía,Altarejos, Joaquín,Nogueras, Manuel,Sánchez, Adolfo
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p. 5941 - 5949
(2007/10/03)
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- Total Synthesis of (-)-Ambrox from S-(+)-Carvone (part 6)
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Conjugate addition of cyanide and allyl nucleophiles to S-(+)-carvone followed by annulation with methyl vinyl ketone gave the substituted decalones 2 and 3 stereoselectively.Both decalones were transformed into (-)-Ambrox via modification of the sidechain, methylation, conversion of the isopropenyl group and cyclization.
- Verstegen-Haaksma, Anja A.,Swarts, Henk J.,Jansen, Ben J. M.,Groot, Aede de
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p. 10095 - 10106
(2007/10/02)
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