35124-13-1Relevant articles and documents
Enzyme-mediated preparation of (+)- and (-)-cis-α-irone and (+)- and (- )-trans-α-irone
Brenna, Elisabetta,Fuganti, Claudio,Fronza, Giovanni,Malpezzi, Luciana,Righetti, Annalisa,Serra, Stefano
, p. 2246 - 2259 (1999)
The preparation of (-)- and (+)-trans-α-irone (1a and 1b, resp.) and of (+)- and (-)-cis-α-irone (1c and 1d, resp.) from commercially available Irone alpha is reported. The relevant step in the synthetic sequence is the initial chromatographic separation
Enzyme-Mediated Preparation of (+)- and (-)-β-Irone and (+)- and (-)-cis-γ-Irone from Irone alpha
Brenna, Elisabetta,Delmonte, Marco,Fuganti, Claudio,Serra, Stefano
, p. 69 - 86 (2007/10/03)
The (-)- and (+)-β-irones ((-)- and (+)-2, resp.), contaminated with ca. 7-9 percent of the (+)- and (-)-trans-α-isomer, respectively, were obtained from racemic α-irone via the 2,6-trans-epoxide (+/-)-4 (Scheme 2). Relevant steps in the sequence were the LiAlH4 reduction of the latter, to provide the diastereoisomeric-4,5-dihydro-5-hydroxy-trans-α-irols (+/-)-6 and (+/-)-7, resolved into the enantiomers by lipase-PS-mediated acetylation with vinyl acetate. The enantiomerically pure allylic acetate esters (+)- and (-)-8 and (+)- and (-)-9, upon treatment with POCl3/pyridine, were converted to the β-irol acetate derivatives (+)- and (-)-10, and (+)- and (-)-11, respectively, eventually providing the desired ketones (+)- and (-)-2 by base hydrolysis and MnO2 oxidation. The 2,6-cis-epoxide (+/-)-5 provided the 4,5-dihydro-4-hydroxy-cis-α-irols (+/-)-13 and (+/-)14 in a 3:1 mixture with the isomeric 5-hydroxy derivatives (+/-)-15 and (+/-)-16 on hydride treatment (Scheme 1). The POCl3/pyridine treatment of the enantiomerically pure allylic acetate esters, obtained by enzymic resolution of (+/-)-13 and (+/-)-14, provided enantiomerically pure cis-α-irol acetate esters, from which ketones (+)- and (-)-22 were prepared (Scheme 4). The same materials were obtained from the (9S) alcohols (+)-13 and (-)-14, treated first with MnO2, then with POCl3/pyridine (Scheme 4). Conversely, the dehydration with POCl3/pyridine of the enantiomerically pure 2,6-cis-5-hydroxy derivatives obtained from (+/-)-15 and (+/-)-16 gave rise to a mixture in which the γ-irol acetates 25a and 25b and 26a and 26b prevailed over the α- and β-isomers (Scheme 5). The (+)- and (-)-cis-γ-irones ((+)- and (-)-3, resp.) were obtained from the latter mixture by a sequence involving as the key step the photochemical isomerization of the α-double bond to the γ-double bond. External panel olfactory evaluation assigned to (+)-β-irone ((+)-2) and to (-)-cis-γ-irone ((-)-3) the strongest character and the possibility to be used as dry-down note.
Acetylation of racemic cis- and trans-α-irols, mediated by Porcine Pancreatic Lipase (PPL) - A new route to (-) and (+)-cis-α-irone
Aleu, Josefina,Bergamo, Beatrice,Brenna, Elisabetta,Fuganti, Claudio,Serra, Stefano
, p. 3031 - 3038 (2007/10/03)
The mixture of the four racemic stereoisomers of α-irol (5-8) was submitted to PPL-mediated acetylation; cis-α-irol 8b was converted more quickly than any other diastereoisomer and in enantiopure fashion. By chance, this latter derivative was the precursor of (-)-cis-α-irone, the stereoisomer showing the strongest Orris butter character. Suitable manipulation of the material left changed by PPL provided (+)-cis-α-irone. PPL's mode of transformation of epoxy trans- and cis-α-irols was investigated, in order to ascertain the effect of chemical structure on the discriminating properties of this enzyme.
Synthesis of both enantiomers of cis-α-irone and cis-γ-irone, principal constituents of iris oil, via resolution of (±)-2,2,4-trimethyl-3-cyclohexene-1-carboxylic acid
Inoue, Takahiro,Kiyota, Hiromasa,Oritani, Takayuki
, p. 3807 - 3818 (2007/10/03)
The principal constituents of iris oil, (-)-cis-α-irone and (-)-cis-γ-irone, and their enantiomers, were synthesized from (-)- and (+)-2,2,4-trimethyl-3-cyclohexene-1-carboxylic acids. The racemic acid was resolved by recrystallization of its salt with a chiral amine, or by enzymatic hydrolysis of the corresponding alcohol. The fragrances of (-)-(1R,5S)-cis-α-irone and (-)-(1R,5S)-cis-γ-irone were superior to those of (+)-(1S,5R)-cis-α-irone and (+)-(1S,5R)-cis-γ-irone. Copyright (C) 2000 Elsevier Science Ltd.
Synthesis of (+)- and (-)-cis-α-irones
Ohtsuka,Itoh,Oishi
, p. 2540 - 2544 (2007/10/02)
A stereocontrolled total synthesis of natural (+)-cis-α-irone (1) is described. The key intermediate (+)-hemiacetal 15 was prepared from the diene 10 in six steps. The crucial optical resolution of (+)-15 was achieved by initial stereoselective conversion into the corresponding l-menthyl acetals 16 and 17 followed by separation and hydrolysis. One of the optically pure enantiomers of 15 was transformed to (-)-18 and then to (+)-1 in seven steps. The synthetic (+)-1 was found to be identical with the natural (+)-cis-α-irone. The isomeric (-)-cis-α-irone was also synthesized from the other enantiomer of 15, via (+)-18.
