Cycloheptanone 4- -2,2-dimethyl

The reaction of methyl propiolate (82) with acyclic enamines produces acyclic dienamines (100), as was the case with dimethyl acetylenedicarboxylate, and the treatment of the pyrrolidine enamines of cycloheptanone, cyclooctanone, cycloundecanone, and cyclododecanone with methyl propiolate results in ring enlargement products (100,101). When the enamines of cyclohexanone are allowed to react with methyl propiolate, rather anomalous products are formed (100). The pyrrolidine enamine of cyclopentanone forms stable 1,2-cycloaddition adduct 83 with methyl propiolate (82). Adduct 83 rearranges to the simple alkylation product 84 upon standing at room temperature, and heating 83 to about 90° causes ring expansion to 85 (97,100). 

Cyclooctanone has been prepared by distilling the calcium and thorium salts of azelaic acid, by heating azelaic acid with barium oxide in the presence of iron, by the action of nitrous acid on l-(aminomethyl)-cycloheptanol, by Dieckman cyclization of azelaic acid dimethyl ester and diethyl ester, and by ring expansion of cycloheptanone with diazomethane. ... 

H-Isoindol 6-Amino-l,2-dimethyl-E6b/1, 485 (Lactam + R —M) Malonsaure Cycloheptyliden- -dinitril E6a, 229 (Cycloheptanon + NC-CH2-CN)... 

In hydrogenolyses with HAICU, the dimethyl acetals of cyclobutanone and cyclohexanone are cleaved more slowly than that of 3-pentanone, while those of cyclopentanone and cycloheptanone are cleaved more rapidly (Table 1), as would be expected for a carbonium ion process. The differences in rate are small, suggesting that carbonium ion character is not strongly developed in the transition state. With the dimethyl acetal of 4-t-butylcyclohexanone, the hydride addition step occurs with strongly predominating axial addition when HAlCh is used Zn(BH4)2 with TMS-Cl, and TMS-H with TMSO-Tf are less selective (Table 2). Equatorial attack predominates, however, in the reduction of the ketone itself with TBDMS-H and TBDMS-OTf. ... 

Butadiene telomerizes with chiral cyclohexanone-derived enamines under substrate control with (5)-2-(methoxymethyl)pyrrolidine (SMP) or its a,a-dimethyl analog as chiral auxiliary12. After removal of the auxiliary by hydrolysis, 2-[( )-2,7-octadienyl]cyclohexanone (6) is obtained in 57 % yield with 72 % ee (R = H) or in 60 % yield with 92 % ee (R = CH3). Cyclopen-tanones, cycloheptanones and cyclooctanones can be similarly converted. 

Full details have been published on the hydroboration of acyclic oteo-dienes, using monochloroborane etherate, and on the conversion of the cyclic boranes so obtained into carbocycles. Thus hexa-1,5-diene was treated with monochloroborane to give a mixture of chlorodialkylboranes which were thermally depolymerized and treated with methanol (Cl - OMe) and dichloromethyl methyl ether to give a mixture of cycloheptanone and 2-methylcyclohexanone (74% total yield) in a 90.5 9.5 ratio, respectively. 2,5-Dimethylhexa-1,5-diene was similarly converted into 3,6-dimethyl-cycloheptanone. ° Hepta-1,6-diene has been converted into cycloheptane (67%) by treatment with diborane and then alkaline AgNOj in a new cyclization procedure. Diketones (35 n = 1, 2, or 3) cyclize to give acylcyclopentenes rather than cyclo-heptenones. ... 

Under slightly different conditions, using 1,3-propanedithiol, acyloins and acyloin acetates lead to the formation of 1,3-dithianes where hydrogen has replaced the hydroxyl or acetoxyl groups . Hydrolysis to the ketone provides a method of converting acyloins to ketones and desulphurization allows conversion of acyloins to hydrocarbons (equation 10). Reduction of l,l-dimethyl-5-hydroxysila-4-cycloheptanone gave l,l-dimethylsila-4-cycloheptanone by this method (equation 11) . A similar reaction is believed to be involved in the action of D-proline reductase . ... 

An equimolecular amount of ethereal ca. 0.5 N mesitylmagnesium bromide added dropwise to an ethereal soln. of l,l-dimethyl-2-cycloheptanone, after... 

A soln. of N,N -dimethyl-N,N -dinitroso6xamide in methanol added dropwise with stirring and cooling to a mixture of cyclohexanone, K-carbonate, Na-sulfate, and methanol, the product isolated after 1 hr. when the Liebermann test is negative cycloheptanone. Y 71.5%. Also prepn. of diazomethane, as gas and in soln., as well as other diazoalkanes, by adding an ethereal soln. of N,N -dialkyl-N.N -dinitroso6xamide to a soln. of Na in butanol, s. H. Reimlin-ger, B. 94, 2547 (1961) prepn. of diazomethane from bis-(N-methyl-N-nitroso)-terephthalamide cf. J. A. Moore and D. E. Reed, Org. Synth. 47, 16 (1961) from N-methyl-N-nitrosourethan cf. P. Gourtot, Bl. 1962, 1493. 

Bromocycloheptanone is reduced to cycloheptanone by titanocene dichloride and magnesium. Vinyl acetates, including 1- and 2-acetoxycyclohepta-1,3-dienes, have been prepared from vinyl bromides using copper(i) acetate. a-Formylcyclo-heptanone reacts with 2,2-dimethyl-3-dimethylamino-2ff-azirine to give adduct (320). Electrochemical reduction of some seven-membered cyclic P-diketones has been studied polarographically/ ... 

Recently, Li NMR spectroscopy has been used to establish that, in many cases, these oligomers do remain intact in solution. Thus, the enolate of cyclohexanone is dimeric in solution when TMEDA, Me2NCH2CH2NMe2, is added, but is a cubic tetramer in THE solutions. The predominance of dimers in TMEDA seems to be fairly general, including the enolates of cyclopentanone, cycloheptanone, 3,3,-dimethyl-2-butanone, acetophenone, and 2,5- dimethylp entanone. 

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