Isophorone reduction

Isophorone usually contains 2—5% of the isomer P-isophorone [471-01-2] (3,5,5-trimethyl-3-cyclohexen-l-one). The term a-isophorone is sometimes used ia referring to the a,P-unsaturated ketone, whereas P-isophorone connotes the unconjugated derivative. P-lsophorone (bp 186°C) is lower boiling than isophorone and can be converted to isophorone by distilling at reduced pressure ia the presence of -toluenesulfonic acid (188). Isophorone can be converted to P-isophorone by treatment with adipic acid (189) or H on(Ill) acetylacetoate (190). P-lsophorone can also be prepared from 4-bromoisophorone by reduction with chromous acetate (191). P-lsophorone can be used as an iatermediate ia the synthesis of carotenoids (192). 

Highly mesoporous carbon supported Pd catalysts were prepared using sodium formate and hydrogen for the reduction of the catalyst precursors. These catalysts were tested in the enantioselective hydrogenation of isophorone and of 2-benzylidene-l-benzosuberone. The support and the catalysts were characterized by different methods such as nitrogen adsorption, hydrogen chemisorption, SEM, XPS and TPD. 

Selective 1,4-reduction of unsaturated aldehydes and ketones by 6 occurs smoothly in THF between —25 °C and room temperature within a few hours (Eq. 5.7). Particularly noteworthy is the realization that phosphines are noticeably absent from the reaction medium. The analogous combination of CuCl/BusSnH in N-methyl-2-pyrrolidinone (NMP) or DMF does not behave identically [22], failing to react with the hindered substrate isophorone, whereas a 72% yield of the corresponding reduced ketone is formed with reagents XCu(H)Li/Bu3SnH. Nonetheless, a form of CuH is being generated in this more polar medium, effectively utilized by Tanaka to arrive at 3-norcephalosporin 8 upon reaction with allenic ester 7 (Scheme 5.3). 

Reduction of a, ji-epoxy ketones with NaHTe (typical procedure) ji-Epoxy ketonesP To a solution of NaHTe (prepared from Te (1.30 g, 10 mmol) and NaBH (0.90 g, 0.24 mmol)) in EtOH is added isophorone oxide (0.616 g, 4 mmol) in EtOH (4 mL). An instantaneous... 

Environmental Fate. Sensitized photolysis studies in water and oxidation/reduction studies in both air and water are lacking, as are biodegradation studies in surface and groundwaters. These kinds of studies are important, since they represent the fundamental removal mechanisms available to isophorone in the environment. In addition, the kinetic studies for the atmospheric reactions are important for understanding the significance of a removal mechanism and predicting the reactions that may control the fate of a chemical in the environment. 

An alternative procedure is to convert the carbonyl compound into the toluene-p-sulphonylhydrazone,12 followed by reduction with either sodium borohydride in acetic acid,13 or with catecholborane, followed by decomposition of the intermediate with sodium acetate or tetrabutylammonium acetate.14 The former method is illustrated by the conversion of undecan-6-one into undecane (Expt 5.6), and the latter by the conversion of acetophenone into ethylbenzene (Expt 6.4, Method B). A feature of these methods is that with a, / -unsaturated ketones, migration of the carbon-carbon multiple bond occurs thus the tosylhydrazone of isophorone gives 3,3,5-trimethylcyclohex-l-ene, and the tosylhydrazone of oct-3-yn-2-one gives octa-2,3-diene. 

Reduction of C=C Bonds. The reduction of the C=C double bond of isophorone (26) with Pd/C in the presence of (S)-proline yields the saturated ketone (27) with 60% optical purity (eq 10). - With (S)-proline ester/Pd (or Pt) systems the hydrogenation of ethyl pyruvate, an a-keto ester, was investigated, but only insignificant enantioselectivities were reached. ... 

A technical synthesis of (4i ,6/ )-4-hydroxy-2,2,6-trimethylcyclohexanone (85) starting from the readily available oxo-isophorone (86) has been described. (85) is an ideal precursor for the synthesis of optically active hydroxylated carotenoids (e.g. zeaxanthin). Chirality was introduced at C-6 (C-3, carotene numbering) by a stereoselective reduction of the double bond by baker s yeast." ... 

Further reactions on these compounds lead to other oxidised products in which the lack of stereochemical control in the epoxidation is unimportant, so, for example isophorone oxide rearranges with various catalysts to the cyclopentanone 182 (80% yield) while both isomers of pulegone oxide 179 gives the cycloheptadione29 183 (78% yield). Exhaustive methylation of the extended enolate produced by reduction of 181 gives 184 in good yield.28... 

Kinetic investigation of the Pd/carbon-(S)-proline system in reduction of isophorone and acetophenone and comparison with known enantioselective hydrogenations were carried out. An addition reaction of (S)-proline with the substrates, and the selective hydrogenation of this adduct results in the optically active products, the kinetic analysis verified this mode of action these are rather diastereoselective reactions. 

Farkas and Tungler et al. studied the support effects in the enantioselective hydrogenation of isophorone over Pd catalysts prepared on different carbon supports with different specific surface areas and on activated carbons with different surface chemistries. The Pd catalysts, obtained by different reduction methods of the catalyst precursors had different dispersions, and the... 

Sipos, E., Farkas, G., Tungjer, A., Figueiredo, J.l. (2002) Enantioselective hydrogenation of isophorone with titania supported Pd catalysts modified with (-)-dihydroapovincaminic acid ethyl ester effect of the support and the reduction method, J. Mol. Catal. A. Chem. 179,107-112. 

A key step in the large-scale production of isophorone diamine (IPDA, Degussa) is simultaneous hydrogenation of a nitrile group and reductive amination of a keto function from isophoronenitrile (IPN) to give the corresponding diamine using a catalyst based on cobalt, nickel or ruthenium or mixtures thereof (Eq. 8-15) [4] ... 

Kutney s approach started with isophorone 84, which was converted into the dibenzoate 85, and thence to the acid 86 on treatment with indolyhnagnesium iodide. Conversion to the acid chloride followed by treatment with indolylmagnesium iodide, induced cyclization to the trans-taseA tetracycle 87. Base-catalyzed epimerization to the cM-fused tetracyclic ketone 88, followed successively by hydride reduction, conversion into the benzoate, treatment with the indole Grignard reagent, and deprotection, gave YCK (73) (Scheme 4). The overall yield was however low (4%), but the method allows access to 6a-c z-YCK via the ketone 87 (57,55). 

General procedure for a CuH-catalyzed asymmetric 1,4-reduction of isophorone in... 

A route to the key synthon (47 ,67 )-4-hydroxy-2,2,6-trimethylcyclo-hexanone had previously been developed by Leuenberger et al. 124) starting from the readily available isophorone. The chiral centre was introduced by enantioselective reduction with bakers yeast, and regio-selective reduction of one keto group was achieved by chemical reduction with nickel catalyst or by triisobutylaluminium under conditions where the desired trans diastereomer was the major product. 

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