31089-90-4

Upstream product

• 61899-98-7 2,6,6-trimethylcyclohex-2-en-1-ylidene ketene 
• 2622-05-1 allylmagnesium bromide 
• 28043-10-9 methyl 2,6,6-trimethyl-cyclohex-2-en-1-yl carboxylate 
• 49815-62-5 4-(2',6',6'-trimethyl-2'-cyclohexenyl)-1,6-heptadien-4-ol 
• 28897-23-6 1-(2,6,6-trimethyl-2-cyclohexenyl)-3-buten-1-ol 
• 61899-99-8 2,6,6-trimethyl-2-hexene-1-carbonyl chloride 
• 14505-74-9 α-cyclocitral 
• 113793-69-4 2,6,6-Trimethyl-cyclohex-2-enecarbothioic acid S-phenyl ester 

Downstream Products

• 24720-09-0 α-damascone 
• 116497-11-1 (2E)-1-[(S)-2,6,6-trimethylcyclohex-2-enyl]but-2-en-1-one 

Relevant academic research and scientific papers

SYNTHESIS OF α-DAMASCONE AND 1-(2,6,6-TRIMETHYL-2-TETRAHYDROPYRANYL)-2-ALKEN-1-ONES

α-Damascone was obtained by the reaction of α-cyclocitral with allyl bromide in the presence of zinc, followed by oxidation of the obtained alcohol with chromic acid to the ketone and isomerization of the latter with triethylamine as catalyst.The analogous synthesis of β-damascone from 1-(4,6,6-trimethyl-1,3-cyclohexadienyl)-2-buten-1-one was impossible on account of complications at the oxidation stage.The rearrangement of the acetylenic alcohols with polyvanadioorganosiloxane as catalyst led to 1-(2,6,6-trimethyl-2-tetrahydropyranyl)-2-alken-1-ones.

Reaction of Ester Enolates with Nucleophiles. Stereocontrolled Formation of Ketone and Aldehyde Enolates

Lithium enolates of carboxylic and thiocarboxylic esters react with nucleophiles to afford ketone and aldehyde enolates and subsequently their enol silyl ethers diastereoselectively.This reaction is applied to the synthesis of γ-damascone, α-damascone, β-safranal, and artemisia ketone.

172. β-Cleavage of Bis(homoallylic) Potassium Alkoxides. Two-Step Preparation of Propenyl Ketones from Carboxylic Esters. Synthesis of ar-Turmerone, α-Damascone, β-Damascone, and β-Damascenone

The transformation of 36 bis(homoallylic) alcohols VII to alkenones IX and X via β-cleavage of their potassium alkoxides VIIa in HMPA has been investigated (cf.Scheme 2).These studies have established an order of β-cleavage for 2-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2-propenyl, and benzyl groups in alkoxides 49a-56a and have allowed a comparison between the β-cleavage reaction and the oxy-Cope rearrangement in alkoxides 74a-83a.As illustrative synthetic applications, a two-step preparation of propenyl ketones 15-42 from carboxylic esters is described, together with syntheses of ar-turmerone (48), α-damascone ((E)-71), β-damascone ((E)-109), and β-damascenone ((E)-111).

GRIGNARD AND HYDRIDE ADDITION TO A KETENE INTERMEDIATE: A NOVEL ACCESS TO α-DAMASCONE AND α-CYCLOCITRAL

α-Damascone (1), a rose fragrance chemical, was synthesized by an allylmagnesium chloride addition to ketene 7 as key step.When the same ketene 7 was reduced by two different aluminium hydride reagents, α-cyclocitral was obtained.The presumed intermediates, enolates II and III, were first trapped as silyl enol ethers and then hydrolyzed with D2O to give the expected α-monodeuterated carbonyl compounds.Mixed aluminium hydride reduction of ketenes is recommended as a facile entry into the chemistry of aldehyde enolates.

Process for the preparation of polyunsaturated cycloaliphatic ketones

Polyunsaturated ketones of formula STR1 having a double bond in position 2' or 3' of the side chain and possessing either an isolated double bond in position 1 or 2, or two conjugated double bonds in positions 1 and 3 of the ring, as indicated by the dotted lines, and wherein index n stands for integer 1 or 2, and each of the symbols R1 to R7, identical or different, designates a hydrogen atom or a lower alkyl radical, are prepared by a process which makes use of tertiary diallyl carbinols as starting materials.

Alkenoyl-cyclohexadienes

New cycloaliphatic unsaturated ketones and their use as perfuming and odour-modifying agents in the manufacture of perfumes and perfumed products, and as flavouring and taste-modifying agents in the preparation of foodstuffs in general and imitation flavours for foodstuffs, beverages, animal feeds, pharmaceutical preparations and tobacco products. Methods for the preparation of said cycloaliphatic unsaturated ketones.