2- Methylcyclohexanone, and

The magnitude of the preference for the formation of the less substituted enamine from unsymmetrical ketones as expressed by the general rule given above is not entirely clear. House and Schellenbaum 48) have reported that 2-methylcyclohexanone and pyrrolidine produce a product mixture of tetra- and trisubstituted enamines in a ratio of 15 85. The estimate of this ratio was made from NMR data. In contrast Stork and co-workers (9) report the formation of 100% trisubstituted enamine as determined by NMR spectroscopy. 

In contrast, 2-methylcyclohexanone and 2-methylindanone were racemized during imine hydrolysis with sodium acetate/acetic acid/pentanc/water8. In the preparation of 2-isopropyIcy-clohexanone and 2-isopropyl-6-methylcyclohexanone enantiomeric excess of the final products was low due to racemization8. 

THE FORMATION AND ALKYLATION OF SPECIFIC ENOLATE ANIONS FROM AN UNSYMMETRICAL KETONE 2-BENZYL-2-METHYLCYCLOHEXANONE AND 2-BENZYL-6-METHYLCYCLOHEXANONE... 

Chiral 2,2-disubstituted cycloalkanones.1 The imine 2 prepared from racemic 2-methylcyclohexanone and (S)-( - )-l, reacts with methyl vinyl ketone to form an adduct that is hydrolyzed to the (R)-( + )-diketone 3 in 91% ee with recovery of 1 in almost quantitative yield. The reaction is described as a deracemizing alkylation. ... 

Methylcyclohexanone and suberone (cycloheptanone) oximes correspondingly give 7-methyl-4,5,6,7-tetrahydroindole (33, yield 70%), its N-vinyl derivative [34, yield 80% (75MI1)], and 4,5,6,7,8-pentahydro-l//-cyclohepta[6]-pyrrole [35, yield 79% (76MIP1 80KGS1299)] (Table XIX). 

The deuteriated (97%) imines 363 and 365, and the hydrazone 364 have been prepared396-399 by treating 2,6,6-trideuterio-2-methylcyclohexanone and 2,2,6,6-tetradeuteriocyclohexanone with the corresponding deuteriated ammonium salts (RND3CI) and used in the KIE studies of the metalation of the above C=N compounds with lithium diisopropylamide (LDA) in THF, in N, N, N A -tetramethyl ethylenediamine (TMEDA) and in dimethylethylamine (DMEA) solvents (equation 200). The rates, d[imine]/dt of that of imines 363 and 364 metalation are zero order with respect to [THF], [TMEDA]... 

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... 

It was shown that the rate of formation of the enamine of 3,3-dimethylaziridine is 5 to 10 times faster than that of pyrrolidine with 2-methylcyclohexanone and 1-tetralone, probably due to decreased steric hindrance. However, the yields of monomethylated products are significantly lower with the azetidine enamine92. 

Cyclopentenone annelation, The isomeric adducts 1 of 2-methylcyclohexanone and propargyi alcohol both cyclize regiospecifically to the hydrindanone 2 (70%... 

Palladium(0)-catalyzed a-allylations of TMS enol ethers can be carried out cleanly with allylic carbonates. These reactions are highly regioselective, e.g. the mtne- and less-substituted TMS enol derivative of 2-methylcyclohexanone cf. Scheme 37) gave 2-allyl-2-methylcyclohexanone and 2-methyl-6-allylcyclohexanone, respectively. Allylations of aldehyde silyl enol ers occur similarly. Allylations of enol acetates occur with allyl carbonates in the presence of catalytic amounts of palla-dium(0) complexes and tri-n-butyltin methoxide. ... 

Isopropylidenation of ketones, >C=0>C=C(CH3)2. Posner et al. have developed an efficient two-step method for effecting isopropylidenation of ketones. The ketone is treated with dibromomethylenetriphenylphosphorane, generated in situ from triphenylphosphine and carbon tetrabromide (4, 550-551). This reaction proceeds in good yield (80-85%) in the case of unhindered ketones hindered ketones such as 2-methylcyclohexanone and 5-non-anone do not undergo dibromomethylenation. The second step involves reaction... 

In their paper on the preparation of trimethylsilyl enol ethers, House et al. [1] illustrate the generation of lithium enolates with the reaction between 2-methylcyclohexanone and LDA using 1,2-dimethoxyethane as a solvent. The authors do not indicate a temperature range for the lithiation of the ketone, but we found the deprotonation of a variety of ketones to proceed extremely fast and with excellent results at temperatures in the region of — 70 °C. In view of the possibility of aldol condensation, dropwise addition of the ketone to the LDA solution seems advisable. Attempts to prepare enolates from aldehydes RCH2CH=0 and LDA gave, after quenching with trimethylchlorosilane, only unidentified resinous products. 

The reaction of 2,3-dimethyl-4-thienyllithium, 2,5-dimethyl-3-thienyllithium, 2,5-dimethyl-3-thienyllithium and 2,5-dimethyl-4-bromo-3-thienyllithium, prepared by halogen-metal exchange, with (-)-menthone, 2-methylcyclohexanone and 2,6-dimethylcyclohexanone... 

Conjugate addition reactions, including the Robinson annulation, which make use of reactive Michael acceptors such as methyl vinyl ketone, can suffer from low yields of the desired adduct. The basic conditions required for enolate formation can cause polymerization of the vinyl ketone. Further difficulties arise from the fact that the Michael adduct 42 and the original cyclohexanone have similar acidities and reactivities, such that competitive reaction of the product with the vinyl ketone can ensue. These problems can be minimized by the use of acidic conditions. Sulfuric acid is known to promote the conjugate addition and intramolecular aldol reaction of 2-methylcyclohexanone and methyl vinyl ketone in 55% yield. Alternatively, a silyl enol ether can be prepared from the ketone and treated with methyl vinyl ketone in the presence of a Lewis acid such as a lanthanide triflate" or boron tri fluoride etherate (BF3 OEt2) and a proton source to effect the conjugate addition (followed by base-promoted aldol closure). 

Several efficient oxidation reactions with molecular oxygen were developed using transition-metal complexes coordinated by variuos ligands in combination with apprOTriate reductants. Recently, it was found that cyclic ketones such as 2-methylcyclohexanone and acetals of aldehyde such as propionaldehyde diethyl acetal were effectively employed in aerobic epoxidation of olefins catalyzed by cobalt(II) complexes. In the latter case, ethyl propionate and ethanol were just detected in nearly stoichiometric manner as coproducts (Scheme 12), therefore the reaction system is kept under neutral conditions during the epoxidation. 

Predict the position of acid-catalyzed bromination of each of the following ketones (a) 2-butanone, (b) 2-pentanone, (c) 3-methyl-2-butanone, (d) 2-methylcyclohexanone, and (e) methyl cyclohexyl ketone. 

The reduction of 2-methylcyclohexanone and 2-isopropylcyclohexanone by LiAlH was subjected to DFT analysis (B3LYP/6-31G(d,p)) to optimize the TSS. Four TSSs were located for each ketone for the axial and equatorial attacks by LiAlH4. Electronic potential maps were used to investigate the electronic effect of the substituents on TSS stabilization. The lowest unoccupied molecular orbital (LUMO) maps and natural bond orbital (NBO) analysis helped in elucidating the uneven distribution of molecular orbital around the carbonyl tt-plane, and the preference for the hydride attack in terms of tensional and electronic properties. ... 

PROBLEM 15.78 Could looking at symmetry allow you to assign the spectra of 4-methylcyclohexanone, 2-methylcyclohexanone, and 2,3-dimethylcyclopentanone,... 

Atlamsani, A., Bregeault, J. and Ziyad, M. (1993). Oxidation of 2-Methylcyclohexanone and Cyclohexanone by Dioxygen Catalyzed by Vanadium-Containing Heteropolyanions, J. Org. 

How can 2 methylcyclohexanone and 3-methylcyclohexanone be distinguished by acid-catalyzed enolization in D2O ... 

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