Hexan-3-one

In the rearrangement of 4,4-diphenylcyclohexenone to 5,6-diphenylbicyclo-[3.1.0]hexan-2-one, there is a strong preference for formation of the endo phenyl... 

Photochemical cyclohex-2-enoneH> bicyclo (3.1.0) hexan-2-one rearrangement irradiation of testosterone acetate, 322 Photochemical rearrangements of cross-conjugated cyclohexadienones and their photoisomers... 

Photochemical cyclohex-2-enone bicyclo (3.1.0)hexan-2-one rearrangement, 320 Photochemical a-cyclopropyl ketone isomerization, 313... 

The carbonyl complex [Ru(EDTAH)(CO)] has been reported to be a very good catalyst for reactions like hydroformylation of alkenes, carbonylation of ammonia and ammines as well as a very active catalyst for the water gas shift reaction. The nitrosyl [Ru(EDTA)(NO)] is an oxygen-transfer agent for the oxidation of hex-l-ene to hexan-2-one, and cyclohexane to the corresponding epoxide. 

The identification and quantification of potentially cytotoxic carbonyl compounds (e.g. aldehydes such as pentanal, hexanal, traw-2-octenal and 4-hydroxy-/mAW-2-nonenal, and ketones such as propan- and hexan-2-ones) also serves as a useful marker of the oxidative deterioration of PUFAs in isolated biological samples and chemical model systems. One method developed utilizes HPLC coupled with spectrophotometric detection and involves precolumn derivatization of peroxidized PUFA-derived aldehydes and alternative carbonyl compounds with 2,4-DNPH followed by separation of the resulting chromophoric 2,4-dinitrophenylhydrazones on a reversed-phase column and spectrophotometric detection at a wavelength of378 nm. This method has a relatively high level of sensitivity, and has been successfully applied to the analysis of such products in rat hepatocytes and rat liver microsomal suspensions stimulated with carbon tetrachloride or ADP-iron complexes (Poli etui., 1985). 

In the simplest case, the reaction of allyl diazoacetate, the catalyst (iS )-198 or (f )-198 in a concentration as low as 0.1 mol% can still catalyze the formation of enantiomeric-3-oxabicyclo[3.1.0]hexan-2-ones with 95% ee (Scheme 5-60). Substituted alkyl diazoacetates undergo intramolecular cyclopropanation, with similarly high enantiomeric excess (Scheme 5-61).110... 

In some photochemical reactions both Si and T take part in the reaction. For example, both the Si and Tt states of aliphatic ketones, such as hexan-2-one, take part in Norrish type 2 reactions ... 

Stern-Volmer analysis for the quenching of the Norrish type 2 reaction of hexan-2-one by penta-1,3-diene results in a nonlinear plot... 

Intraactions between elections in three-membered rings and unsaturated groups in the same molecule have been detected via 13C chemical-shift variations in a number of instances. Thus, introduction of the carbonyl function in tricy-clo[3.2.1,02,7]decane (e.g., 274) leads to significant downfield shifts of the signals of C(l) (+8.0), C(2) (+15.5), and C(7) (+7.7) (385), whereas corresponding effects in bicyclo[3.1.0]hexan-2-one (275) are smaller (385,386). A corresponding dependence was reported for 276 and 277 and related to more effective electron withdrawal in 276 (387). An even more pronounced deshielding effect was observed by Murata and co-workers (388,389) in the ketone 278 when they compared it with 279. 

R,5S)-(-)-6,6-Dimethyl-3-oxabicyclo[3.1,0]hexan-2-one. Highly tnantioselective Intramolecular Cyclopropanation Catalyzed by Dirhodium(ll) Tetrakis[methyl 2-pyrrolidone-5(R)-carboxylate],... 

The reduction of 2-methylthiophene, however, yielded only small amounts of dihydro-2-methylthiophene and a high yield of pcntcnethiol. It was apparent that substitution in the 2-position inhibited the production of the dihydrothiophene and favored more complete reduction. It was interesting to note that the reduction of 2,5-dimethylthiophene furnished small amounts of hexan-2-one. It was believed that the crude hexenethiol probably contained some hexene-2-thiol-2 which is capable of isomerization to hexane 2-thione from which the ketone can be formed by the action of alkali as follows ... 

The analogous 2,3-dihydro-2,5-dimethylfuran (11.171, R = R = Me) was formed in rats from 5-hydroxyhexan-2-one (11.170, R = R = Me), itself a primary metabolite of hexan-2-one [178], These studies are relevant in the search for the toxic metabolites of alkanes and ketones responsible for... 

Intramolecular hydrogen abstraction from a g carbon occurs when certain ketones are irradiated. For e.g., vapours of Hexan-2-one on photolysis gives an alkene and a ketone (via the enol form). It is referred to as Norrish type II cleavage. 

In a study of the photoisomerization of 4,4-dimethyl-2-cyclohexenone (8) to 6,6-dimethylbicyclo[3.1.0]-hexane-2-one (9) and 3-isopropyl-2-cyclo-pentenone (10), Chapman and Wampfler48 accounted for the pronounced effect of sensitizer concentration by such a self-quenching mechanism. The phenomenon was exhibited by four ketones with () lowest triplet states but not by benzophenone or acetophenone which have (w, n) triplet states.49... 

Special interest has been paid to the synthesis of bridged four-membered rings. The smallest system of this type, the bicyclo[1. l.l]pentane skeleton 6, could be prepared by photolysis of 3-diazobicyclo[2.1.1]hexan-2-one in methanol,43 however, the yield was very low ( 2%). 

Another limitation is seen when extra strain is included in the compound to be reduced. Dehalogenation of 3,3-dichlorobicyclo[2.2.0]hexan-2-one with zinc/ammonium chloride in methanol gave, at best, a 25% yield of 3-chlorobicyclo[2.2.0]hexan-2-one (14) together with cyclohexenone and 6-chlorohex-5-enoic acid.128 The best results were achieved with the zinc/ acetic acid system, while addition of water, silver-promoted zinc reduction in methanol, tri-butyltin hydride reduction or hydrogenolysis with palladium in methanol did not result in formation of 14, but various other ring-opened products. 

Diarylcyclohex-2-enones undergo a different photorearrangement to bicydol3.1.0]hexan-2-ones, in which an aryl substituent migrates from C-4 to C-3 (4.641. This reaction finds a parallel in the di-n-methane rearrangement of 3-phenylalkenes (see p. 54). It is usually efficient (<> — 0.1-0.2), it occurs by way of the (n.Jt ) triplet... 

Irradiation of 4,4-dimethyl-2-cyclohexenone (Formula 83) in tert-butyl alcohol gives 6,6-dimethylbicyclo[3.1.0]hexan-2-one (Formula 84) in good yield with small amounts of 3-isopropyl-2-cyclopentenone (Formula 85) (46). The 3-isopropyl-2-cyclopentenone is formed by photochemical rearrangement of the bicyclic ketone (Formula 84) (46). 

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