Ketones, addition derivatives preparation

In addition to the parent ketones, some derivatives (such as the 2,4-dini-trophenylhydrazones and p-tolylsulfonylhydrazones) have been prepared by the same authors, and this work was covered by a patent.211... 

At an early date it was already recognized that the ketone (IX) derived from an oxidation of the C-18 carbinol function of methyl reserpate could be of considerable utility for further transformation of the reserpine pentacyclic ring system, but early attempts at the preparation of the desired compound by conventional oxidation, e.g., by Oppenauer s method, AAchlorosuceinimide, sodium dichromate, or chromic oxide in pyridine, were unsuccessful with both methyl reserpate and methyl 18-epireserpate. The ketone was finally obtained by heating methyl reserpate p-bromobenzene sulfonate with dimethyl sulfoxide in the presence of triethylamine (162), a method successfully used for simpler compounds (163). Subsequently, it was found that this oxidation could also be realized with other benzene sulfonate esters of methyl reserpate and 18-epireserpate. That the stereochemistry of the molecule was unaffected was proved by sodium borohydride reduction of the ketone, which gave equal amounts of methyl reserpate and its 18-epimer. This and other simple reactions of the ketone are sketched in Chart III, and additional observations will be given. 

Tlie Kresze reaction has also been used in the synthesis of N phosphinoyl imines derived from nonenolizable aldehydes, although usually in modest yields [25, 26]. The N phosphinoyl imine derived from trifluoromethyl ketones can be prepared via the ethanolate intermediate (Scheme 1.7) [27]. This adduct is directly used in the subsequent nucleophilic addition reaction. 

Boron or tin (II) Z-enolates are generated by reaction with the corresponding triflates with a carbonyl compound in the presence of tertiary amines like r-P NEt or. M-ethylpiperidine (except when using dicyclopentylboron triflate [407]). E-Enolates are prepared by using dicyclohexyl- or other cyclic chloroboranes in the presence of Et3N or Me NEt [407, 685, 686, 1246, 1247, 1248], Because enolization does not take place under such conditions with esters or aliphatic tertiary amides, thiophenyl esters RGH COSPh have been used as ester/amide substitutes. Furthermore, Z-boron enolates of ketones can be prepared by conjugate addition of acid derivatives of dialkylboranes to a-enones [687],... 

Chiral -substituted carbonyl compounds have been prepared in high optical purity (64-98%) by the use of organoaluminium chemistry. Thus treatment of an acetal derived from an a, 6-unsaturated aldehyde and R,R- tartaric acid diamide with a trialkylalane gives largely the 1,4- addition product from which the desired ketone is derived by ozonolysis (Scheme 12). 1... 

Hydroxy-ester enolates are oxidized by iodine at — 78°C to give the least hindered oxiran. Thus, by generating the /3-hydroxy-ester from a ketone and acetate enolates, the overall conversion represents a stereoselective Darzens condensation. Glycidic esters can also be obtained from the corresponding nitriles via iminoether derivatives prepared by alkoxide-catalysed addition of alcohols to the nitrile group. 

In addition, ketones can be prepared from certain carboxylic acid derivatives, just as aldehydes can. Among the most useful reactions of this type is that between an acid chloride and a lithium diorganocopper reagent, R2CuLi. We ll discuss lithium diorganocopper reagents later in this chapter (Section 14.11) and will look at preparing ketones from acid chlorides in Section 16.4. 

CHaCOCeHs 2 equivalents of 3-picoline in an equal volume of benzene added at 5° to 2 equivalents of a suspension of Na-diisopropyl-amide in benzene, stirred 30 min. at 5°, 1 equivalent of ethyl benzoate in an equal volume of benzene added, and stirred an additional hr. at 5° 3-phenacylpyridine. Y 78%.—Similarly, alkyl 3-picolyl ketones have been prepared, for the first time. F. e., also with other pyridine derivatives... 

Other modifications of the polyamines include limited addition of alkylene oxide to yield the corresponding hydroxyalkyl derivatives (225) and cyanoethylation of DETA or TETA, usuaHy by reaction with acrylonitrile [107-13-1/, to give derivatives providing longer pot Hfe and better wetting of glass (226). Also included are ketimines, made by the reaction of EDA with acetone for example. These derivatives can also be hydrogenated, as in the case of the equimolar adducts of DETA and methyl isobutyl ketone [108-10-1] or methyl isoamyl ketone [110-12-3] (221 or used as is to provide moisture cure performance. Mannich bases prepared from a phenol, formaldehyde and a polyamine are also used, such as the hardener prepared from cresol, DETA, and formaldehyde (228). Other modifications of polyamines for use as epoxy hardeners include reaction with aldehydes (229), epoxidized fatty nitriles (230), aromatic monoisocyanates (231), or propylene sulfide [1072-43-1] (232). 

Various alkylating agents are used for the preparation of pyridazinyl alkyl sulfides. Methyl and ethyl iodides, dimethyl and diethyl sulfate, a-halo acids and esters, /3-halo acids and their derivatives, a-halo ketones, benzyl halides and substituted benzyl halides and other alkyl and heteroarylmethyl halides are most commonly used for this purpose. Another method is the addition of pyridazinethiones and pyridazinethiols to unsaturated compounds, such as 2,3(4//)-dihydropyran or 2,3(4//)-dihydrothiopyran, and to compounds with activated double bonds, such as acrylonitrile, acrylates and quinones. 

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