D-3-Methylcyclohexanone

Information regarding the position of the substituents can be obtained from the mass spectra of the enamines of cyclic ketones. For instance in the case of the morpholine enamine of 3-methylcyclohexanone, which is shown to be a 2 1 mixture of/ and isomers by NMR spectroscopy, the fragmentation of the radical ion from the /) isomer results in the loss of a methyl radical from the C-3 position. The d isomer gives a complicated spectrum due to the loss of the hydrogen radical. 

FIGURE 12. (a) (+)-trmethylcyclohexanone conformations and octant projection diagrams. (b) CD spectra in methanol (-------) and isooctane (---). [Reproduced from D. A. Lightner,... 

Figure 8 Guest-dependent polymorphism in CA inclusion crystals with (a) acetophenone, (b) y-valerolactone, (c) ethynylbenzene, (d) 2-fluoropropiophenone, (e) m-chloroaniline, (f) water (Form I), (g) water (Form II), (h) 3-methylcyclohexanone, (i) acetic acid, (j) m-fluoroaniline, (k) 1,2,3-trimethylbenzene, and (1) acrylonitrile. Hydrogen atoms are omitted for clarity. Carbon, nitrogen and oxygen atoms are represented by open, gray and tilled circles, respectively. 

At an early stage Kitagawa and co-workers followed a path which, unfortunately, did not reach the goal (57). Starting from d-camphor, building block 43 (Scheme 10) was reached via various steps (58). Resolution of diastereomeric ketals of cyclopropanated 3-methylcyclohexanone likewise yielded the chiral... 

Minato et have reported the isolation of acorenone (149) from Acorus calamus L. The physical properties (m.p., [ajp) which they ascribe to this compound are markedly different from two previous sets of data. Hydrogenation ofacorenone is reported to give isoacorone (150 R = Me, = H)andacorone (150 R = H, R = Me). Recently, Conia et al. have demonstrated that thermal cyclization (220 °C) of the appropriately substituted cyclohexanone (151) [derived from (-+- )-3-methylcyclohexanone] yielded four isomeric spiro-diketones closely related to the acorane skeleton. The intermediacy of the isopropylidene isomer (152) was indicated and from a detailed study of n.m.r. solvent shifts and c.d. spectra it was concluded that these four spiro-diketones can be represented as (153)—(156). 

With the aid of molecular models and diagrams, indicate whether you would expect the following to be chiral (a) trans-cyclohexane-1,2-dicarboxy Lie acid (b) 3-methylcyclohexanone (c) 1,1,4-trichlorocyclobexane (d) 1,1,2-trichlorocyclohexane (e)... 

This bond selection by functionahty is not very stringent. With many moderately functionahzed targets a large proportion of all skeletal bonds will be dictated in this way, partly because for n functionahzed sites there are ( ) functionality pairs and partly because there are several bonds dictated for construction by any given functional group or any pair (Table 1). As illustration, application of functionahty dissection from Table 1 dictates all skeletal bonds as construction candidates in 3-methylcyclohexanone or in 5, and in cholesterol (d) points to the eleven bonds marked in boldface for construction. 

Ans. (a) 3-Methylcyclohexanone. (b) Common names are used for ketones where one (or both) substituent(s) attached to the carbonyl carbon is (are) cyclic (aromatic or nonaromatic) 2-chloro-phenyl ethyl ketone or o-chlorophenyl ethyl ketone, (c) 4-Methyl-2-heptanone. (d) 2-Chloro-cyclohexanecarbaldehyde. 

Fig. 5 Various host frameworks of CA with (a) methanol (b) acetophenone (c) y-valerolactone (d) ethylnylbenzene (e) 2-fluoropropiophenone (f)m-chloroaniline (g) water (h) acetonitrile (i) 3-methylcyclohexanone (j) acetic acid (k) m-fluoroaniline and (1) 1,2,3-trimethylbenzene.

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. 

Problem 19.4 How would you carry out the following reactions More than one step may be required, (a) 3-Hexvne 3-Hexanone, (b) Benzene —> m-Bromoacetophenone I (c) Bromobenzene —> Acetophenone (d) 1-Methylcyclohexene — 2-Methylcyclohexanone... 

Figure 5. Stereochemical drawings showing the absolute configuration of (a) M-hexahelicene, (b) (5R)-cyclohexa-1,3-diene, (c) (3R)-methylcyclohexanone and (d) (25)-phenylbu-tane.

A sample of racemic 2-methylcyclohexanone-1- 3 was prepared by methylation of the lithium cyclohexanolate-l-13 , with methyl iodide (VI ) The enolate was prepared from the cyclohexanone-1-13c by way of the trimethyl silyl derivative following the pro-" cedure of House and coworkers (12). A sample of trans-D,l-2-methylcyclohexanol-l -13C was then obtained by reduction of the ketone with lithium aluminum hydride in the presence of aluminum chloride as prescribed by Eliel and coworkers (13). 

The solvent is removed by distillation through a 15-cm. Vigreux column, first at atmospheric pressure and finally at reduced pressure (water aspirator). The residue is satisfactory for the preparation of 2-methyl-2-cyclohexenone described below (part B). Distillation through the column gives, after a small fore-run, 243-248 g. (83-85%) of colorless 2-chloro-2-methylcyclohexanone, b.p. 94-96°/27 mm., d 1.4672, df 1.088 (Note 3). 

More recently, the use of high pressure with tetra-n-butylammonium fluoride as catalyst allowed these reactions to be accomplished with cyclic ketones. Thus, the Henry reaction of nitroalkanes with 3- and 4-methylcyclohexanones in THF at 30 C and 9 kbar (1 bar = 100 kPa) afforded fair to high yields (60-90% after 4 d) of the corresponding nitro alcohols, while with 2-methyIcyclohexanones it was possible to obtain addition products, although in moderate yields. These facts explain the modest utility of the Henry reaction as a chain-lengthening reaction when the carbonyl component is a ketone, but also show the difference in reactivity of aldehyde and ketone C==0 groups with respect to nitromethane, primary and secondary nitroalkanes in the presence of a base as catalyst. Such a difference in reactivity can be considered as the most evident chemoselectivity of this reaction. 

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