Cyclo Heptanones

Introduce a solution of 100 g. of sodium bisulphite in 200 ml. of water and continue the stirring, preferably for 10 hours with exclusion of air. A thick precipitate separates after a few minutes. Collect the bisulphite compound by suction filtration, wash it with ether until colourless, and then decompose it in a flask with a lukewarm solution of 125 g. of sodium carbonate in 150 ml. of water. Separate the ketone layer, extract the aqueous layer with four 30 ml. portions of ether, dry the combined organic layers over anhydrous magnesium sulphate, remove the ether at atmospheric pressure, and distil the residual oil under reduced pressure from a Qaisen flask with fractionating side arm (Fig. II, 24, 5). Collect the cyclo-heptanone at 64r-65°/12 mm. the yield is 23 g. 

A 8-endo-trig cyclization leading to a cyclo-octanone, foreseeable in the case of a o-homoallylic benzoyl tellnride, did not occnr. Snch a resnlt was achieved, however, with a more conformationally nnstrained snbstrate A. Treatment of the product with H2O2 furnishes a 3.7 1 mixture of the desired dibenzocyclooctanone B and the methylene cyclo-heptanone C. 

Tropolone has been made from 1,2-cycloheptanedione by bromination and reduction, and by reaction with N-bromosuccinimide from cyclo-heptanone by bromination, hydrolysis, and reduction from diethyl pimelate by acyloin condensation and bromination from cyclo-heptatriene by permanganate oxidation from 3,5-dihydroxybenzoic acid by a multistep synthesis from 2,3-dimethoxybenzoic acid by a multistep synthesis from tropone by chlorination and hydrolysis, by amination with hydrazine and hydrolysis, or by photooxidation followed by reduction with thiourea from cyclopentadiene and tetra-fluoroethylene and from cyclopentadiene and dichloroketene. - The present procedure, based on the last method, is relatively simple and uses inexpensive starting materials. Step A exemplifies the 2 + 2 cycloaddition of dichloroketene to an olefin, " and the specific oycloadduot obtained has proved to be a useful intermediate in other syntheses. " Step B has been the subject of several mechanistic studies, " and its yield has been greatly improved by the isolation technique described above. This synthesis has also been extended to the preparation of various tropolone derivatives. - " ... 

Addition, of potassium cyanide to diethyl benzalmalonate, 30, 84 of sodium bisulfite, to cyclo-heptanone, 34, 25 to phenanthrenequmone, 34, 76 Adipyl azide, 36, 70 Adipyl hydrazide, 36, 69 Alanine, 33, 1 Aldehjde collidine, 30, 42 Aldehydes, stabilization against autoxidation, 37, 40 Aldehyde synthesis, 31, 92... 

Enamines derived from relatively reactive amines, such as pyrrolidine and sterically unhindered cyclic ketones, are formed rapidly either with or without acid catalysis35,42. In the case of 2-substituted cyclic ketones (2-methylcyclohexanone,l-tetralone), cyclo-heptanone and higher cyclic ketones on the one hand, and with weakly basic (e.g. morpholine) or hindered amines on the other, the use of toluene solvent and a catalytic amount of p-toluenesulphonic acid affords good yields and shortens the reaction time. 

Cyclic ketones. Diazomethane ring expansion of cyclohexanone gives cyclo-heptanone in yields as high as 63% and smaller amounts of cyclooctanone and methylenecyclohexane oxide. The cycloheptanone is easily separated from the... 

Cyclooctenones 36 were made by cleavage of 8-halo- or 8,8-dihalo-l-(trimethylsiloxy)bi-cyclo[5.1.0]octanes 35, promoted by tetrabutylammonium fluoride in tetrahydrofuran. The cy-clooctenone was usually accompanied by 10-15% of the corresponding (a-halomethyl)cyclo-heptanone 37." For example, 8,8-dichloro-3,3,7-trimethyl-l-(trimethylsiloxy)bicyclo[5.1.0]oc-tane (35, X = Y = Cl) gave a mixture of 36 (Y = Cl, 43%) and 37 (X = Y = Cl, 11%). ... 

Ring contraction of appropriately substituted 1,6-di- or tetrahalocycloheptatrienes or -cyclo-heptanones provides access to the bicyclo[4.1.0]heptene system. Thus l-bromo-6-chlorocyclo-hepta-l,3,5-triene reacted with butyllithium directly to alford benzocyclopropene (la) in 50% yield, presumably via a norcaradiene intermediate. The 2-methyl derivative lb was... 

Cyclohexanones can be dehydrogenated to enones by treatment of the corresponding enol silanes with DDQ in the presence of a catalytic amount of the bis-silyl derivative of acetamide. However, the yields fall off drastically when the reaction is applied to cyclopentanones and cyclo-heptanones. Another new method for dehydrogenation of carbonyl compounds consists of conversion to their pyridine-2-sulfIde derivatives, followed by oxidation (MCPBA), and by mild heat. ... 

Intramolecular Friedel-Crafts acylation provides a useful synthetic approach to cyclic ketones. The cyclization is well-suited to the preparation of six- and particularly five-membered rings, as used in key steps in routes to methyl dihydrojasmonate (equation 3), and precursors to some marine sesquiterpenes (equation 4) and the theoretically interesting spiro[4.4]nonatetraene (equation 5). Extension to cyclo-heptanones has been achieved, - but tars were formed on attempting to prepare cyclooctanones. ... 

Tropidine readily forms a methiodide. When the methiodide is treated with moist silver oxide and the aqueous solution distilled the doubly unsaturated a-methyltropidine (XXVII) is obtained in good yield. The purification of this oil proved difficult for isomerization to /3-methyltropidine occurs at 140-150° (121). The isomerism involves a shift of the double bonds. The /3-isomer is soluble in cold hydrochloric acid but on warming an insoluble and unsaturated ketone (oxime, phenylhydrazone), tropilene, settles out (121). Oxidation of tropilene gives adipic acid, while cyclo-heptanone is formed by its catalytic reduction (160). The preparation of... 

Fischer indole synthesis to cyclohexanone-2-troponylhydrazone and dehydrogenation of the product to indolo[2,3-h]tropone the 8- and 10-isopropyl-, and 7-bromo-analogues, were also prepared. Treatment of the 2-troponylhydrazones of cyclo-heptanone and JV-benzylpiperidinone with acid gave analogous products. Tndolo[2,3-h]tropone was converted into benzo[h]-l-aza-azulene. ... 

There is also considerable Raman data on cyclo-heptanones [44, 45, 189]. 

Equimolar amounts of the startg. cyclopropanone mercaptal and water dissolved at room temp, in trifluoroacetic acid, and allowed to react 5-10 hrs. cyclo-heptanone. Y 90%. F. e. s. D. Seebach, M. Braun, and N. DuPreez, Tetrah. Let. 1973, 3509. 

Though a number of ketones can be reduced on a preparative scale by nicotinamide adenine dinucleotide and sodium dithionite, cyclo-heptanone, -octanone, and -nonanone are not reduced at a practical rate. ... 

A semipinacol rearrangement of symmetrically substituted six-membered cyclic P-hydroxy-a-diazo esters with chiral carboxylic acids was reported to give chiral cyclo-heptanones (Scheme 59)7" ... 

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