2-„-Butyl-2-methylcyclohexanone

Butyl hypochlorite, reaction with cy-clohexylamine, 46, 17 2- -Butyl-2-methylcyclohexanone, 48,40... 

The two isomers cis- and fmns-4-tert-butyl-2-methylcyclohexanone are iivterconverted by base treatment. Which isomer do you think is more stable, and why ... 

Finally, with the aim of discovering novel chiral oxomolybdenum catalysts able to perform enantioselective alkene epoxidations, Kuhn et al. have reported the exploration of the catalytic behaviour of a series of dioxomolybdenum(VI) complexes with chiral cw-8-phenylthiomenthol ligands derived from ( + )-pulegone. Therefore, the epoxidation of c -p-methylstyrene using t-butyl-hydroperoxide as the oxidant and performed in the presence of ( + )-(2i ,5i )-2-[1-methyl-l-(phenylthio)ethyl]-5-methylcyclohexanone oxime as the ligand, did not produce, however, a significant optical induction in these conditions. 

In a 1-1. three-necked flask equipped with a dry ice-acctone condenser and a sealed mechanical stirrer is placed 700 ml. of commercial, anhydrous, liquid ammonia. To the stirred ammonia is added a small piece of potassium metal. (Caution1 Care should he exercised in handling potassium metal, since it is extremely reactive and it ignites on contact with water, atmospheric moisture, or alcohol. It should he manipulated under toluene or xylene, and blotted with filter paper before addition.) After the appearance of a blue color a few crystals of ferric nitrate hydrate (ca. 0.1 g.) are added, followed by small pieces of freshly cut potassium metal until 7.0 g. (0.18 g. atom) has been added. After all the potassium has been converted to the amide (Note 7), 24.9 g. (0.154 mole) of sodio-2-formyl-6-methylcyclohexanone is added carefully through a powder funnel (Note 8). After 1 hour a solution of 28.2 g. (0.21 mole) of w-butyl bromide (Note 9) in 50 ml. of anhydrous ether is added dropwise from an addition funnel. The mixture is stirred for 3 hours, and then the dry ice-acetone condenser is replaced by a water condenser. A steam bath is placed under the flask, and the ammonia is evaporated (Caution ) as 400 ml. of anhydrous ether is added. When the... 

A higher-boiling fraction consisting of 2-formyl-6- -butyl-6-methylcyclohexanone, b.p. 201-203° (20 mm.), is obtained if hydrolysis is not complete. 

The present method affords 2-w-butyl-2-methylcyclohexanone uncontaminated by the isomeric 2- -butyl-6-methylcycIohex-anone. 

Different stereoisomeric cyclohexanols resulted also from reduction of ethyl 4-/ r/-butyl-2-methylcyclohexanone-2-carboxylate with sodium borohydride (equatorial hydroxyl) or with aluminum isopropoxide (axial hydroxyl) [1088]. 

A) (23), was obtained in an improved yield using the modified literature procedure (28) starting from benzene diazonium chloride (1054) and hydroxymethylene-5-methylcyclohexanone (1055). A biomimetic coupling of l-hydroxy-3-methylcarba-zole (O-demethylmurrayafoline A) (23) by reaction with di-ferf-butyl peroxide l(t-BuO)2] afforded the dimer of O-demethylmurrayafoline A (204). Finally, oxidation of 204 with PCC afforded (+ )-bismurrayaquinone-A (215). The resolution of atropo-enantiomers was achieved by chiral HPLC using Chiracel OF. The assignment of the absolute configuration of the two enantiomers (S)-215 and (f )-215 was achieved by comparison of their theoretical and experimental circular dichroism (CD) spectra (166,167,661) (Scheme 5.164). 

Uans-4-itti-butyl-2-methylcyclohexanone dimethylhydrazone, yield 95% 99% dc [(E)j(Z)] 1 1... 

Alternatively, metalation of cyclohexanone imines can be performed with isopropylmagnesium bromide by refluxing in THF for 2 hours1,24. Alkylation of the magnesium azaenolate of the (E)-2-amino butyl ether derivative at —78 °C provides (E)-2-methylcyclohexanone in an overall yield of 52% and 81% enantiomeric excess24. 

Schaefer and Weinberg have reported (126) that the deuterolysis of 4-t-butyl-1-morpholino cyclohexene (477) produced specifically 2-8-deuterio-4-1 -butyl-cyclohexanone (478). Malhotra and Johnson (148) have shown that the enamine of 2-methylcyclohexanone gives on hydrolysis the oU-deuteromethylcyclohexanone 481. This enamine is known to exist in conformation 479 with the methyl group axial. Consequently, axial protonation must have taken place on 479 to give first the imini urn ion 480 which was then hydrolyzed to 481. 

Asymmetric protonations. Deprotonation (LDA) of the imine (2b) obtained from racemic 2-methylcyclohexanone and lb followed by protonation with ethanol and hydrolysis gives (S)-2-methylcyclohexane (3) in 90% ee. The enantioselectivity depends in part on the R group when R = H (2a), (R)-3 is formed in 22% ee. When (-butyl alcohol is used as the proton source, completely inactive 3 is obtained by the same sequence. No enantioselectivity is observed in protonation of the lithioenamine of 2-methylcyclohexanone and nonsupported la.2... 

Reduction of cyclic and bicyclic ketones. This hydride reduces 4-r-butyl- and 3-methylcyclohexanone with some bias favoring formation of the more stable isomer. In contrast, 2-methylcyclohexanone is reduced preferentially to the less stable cis-isomer (72%). Essentially, only the ra-isomer is formed on reduction of 2-f-butylcyclohexanone (98% stereoselectivity). Norcamphor is reduced to the endo-alcohol in > 99% stereoselectivity, whereas the more hindered camphor is reduced to the exo-alcohol with 98% stereoselectivity. 

True solvents are considered to be those solvents that provide resin solutions which can be diluted to infinity without resin precipitation. True solvents for epoxies include MEK, diacetone alcohol, methylcyclohexanone, and most glycol ethers and their acetates. Acetone, not a true solvent, can be used to prepare 40% solutions of high-MW DGEBA epoxy resin, but not a 20% solution. Aromatic solvents such as toluene and xylene, as well as simple alcohols, such as isopropyl and n-butyl alcohol, are not active solvents for DGEBA resins however, they can be used in combination with other solvents to improve solubility. 

The stereochemical course of the annulation process has been determined by reaction of acryloyl chloride with the morpholine enamine of 4-f-butyl-2-methylcyclohexanone. The bicyclic dione was obtained in 76% yield as a 4 1 mixture of two isomers (Scheme 150). X-ray analysis of the main isomer showed that reaction had occurred by axial attack from the same side as the C-2 methyl group. In order for regeneration of the enamine system to occur under conditions of stereoelectronic control, the intermediate ketene-iminium salt presumably adopts a twist conformation. Cyclization of the ketene... 

Stereoselective selenenylation of ketones with chiral selenamines has been utilized as a facile entry to optically active 4-substituted 2-cyclohexenones 9, but with low optical purity6. Thus, the reaction of 4-te/T-butyl- or 4-methylcyclohexanone with chiral selenamines in benzene or tetrahy-drofuran at various temperatures and/or times affords diastereomeric 2-arylseleno-4-/< /7-butyl-and 2-arylseleno-4-methylcyclohexanone (8). Oxidation of these selenides with hydrogen peroxide produces (S)-4-/erf-butyl- or (.S )-4-methyl-2-cyclohexenone (9) in quantitative yield6. 

SH-tert-fiury/- and (S)-4-Methyl-2-cycIohexenone (9) A mixture of 0.37 mmol of 2-arylseleno-4-rerr-butyl- or 2-arylseleno-4-methylcyclohexanone, 0.1 mL of 30% aq H/)2 and THF is stirred at r.t. for 2.5-5 h. The mixture is extracted three times with 20-mL portions of Et,0. The ethereal extracts are combined, washed with 10 mL of 10% aq Na,S,07, dried and concentrated under reduced pressure. The residua oil is subjected to preparative TLC (benzene) to give 9. 

Oxadiazines have also been prepared by the reaction of dibenzoyldiazene with enamines of 4-/er/-butyl- and 2-methylcyclohexanonc, and are further hydrolyzed to disubstituted cyclohexanones18. Mixtures of diastereomers 9 are produced from 2-methylcyclohexanone enamines. but the c 4-2,6-disubstituted cyclohexanone 10 is the exclusive product after acidic hydrolysis and heating in the presence of acetic acid18. 

Reduction of a series of cyclohexanones (2- and 4-methyl, 4-isopropyl, 4-r-butyl and 3,3,5-trimethyl), both in the presence and absence of proton donors gave a 99 1 ratio of equatorial to axial alcohol. For 3-methylcyclohexanone the ratio was 94 6. Also, reduction of menthone (4) affords a 97 3 ratio of equa-... 

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