35124-15-3

Upstream product

• 35124-16-4 (+)-(1'S,3'R,3E)-4-(2',3',3'-trimethyl-6'-methylidenecyclohex-1'-yl)but-3-en-2-one 
• 67-56-1 methanol 
• 35124-13-1 (+)-(2R:6S)-cis-α-irone 
• 7732-18-5 water 
• 86119-84-8 phosphoric acid 
• 82850-90-6 3-<1R-(2,2,3R-trimethyl-6-methylenecyclohexyl)>acrylonitrile 
• 333983-56-5 (-)-(2S,5S,6R,9S)-4,5-dihydro-5-hydroxy-trans-α-irol acetate 
• 333983-03-2 (+)-(2R,5R,6R,9R)-4,5-dihydro-5-hydroxy-cis-α-irol acetate 
• 333983-62-3 (-)-(2R,5R,6R,9S)-4,5-dihydro-5-hydroxy-cis-α-irol acetate 
• 333982-66-4 (+)-(2R,5R,6S,9R)-4,5-dihydro-5-hydroxy-trans-α-irol acetate 
• 333983-53-2 (-)-(2R,5R,6S,9S)-4,5-dihydro-5-hydroxy-trans-α-irol acetate 
• 333983-21-4 (+)-(2S,5S,6R,9S)-4,5-dihydro-5-hydroxy-trans-α-irol 
• 333983-44-1 (+)-(2R,5R,6R,9S)-4,5-dihydro-5-hydroxy-cis-α-irol 
• 333983-18-9 (-)-(2R,5R,6S,9S)-4,5-dihydro-5-hydroxy-trans-α-irol 

Downstream Products

• 124115-56-6 1t-((X)-2.2.3.6-tetramethyl-cyclohexen-⁽⁶⁾-yl)-buten-⁽¹⁾-one-⁽³⁾-(4-phenyl semicarbazone) 

Relevant academic research and scientific papers

Enzyme-Mediated Preparation of (+)- and (-)-β-Irone and (+)- and (-)-cis-γ-Irone from Irone alpha

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.

Synthesis of The Natural Enantiomers of Irones from (+)-Citronellal

Some irone isomers with the natural chirality have been synthesised from (+)-citronellal (7). (+)-Methyl citronellate (21) obtained from compound (7) was methylated stepwise to give methyl 2,2,3,7-tetramethyloct-6-enoate (23).After hydrolysis of the ester