Carboxylic acid from methyl ketones

METHYL KETONES FROM CARBOXYLIC ACIDS CYCLOHEXYL METHYL KETONE... 

Methyl ketones from carboxylic acid chlorides.13 The reagent, 3 moles, prepared in ether solution, reacts with acid chlorides (1 mole) at —78° in 15 minutes to give the corresponding methyl ketones in excellent yield. The acid chloride can be... 

Methyl ketones from carboxylic acid chlorides Synthesis with addition of 1 C-atom... 

Methyl ketones from carboxylic acids COOH COGH3... 

Methyl ketones from carboxylic acids via sodium earboxylates, carboxylic acid chlorides, a-diazokctoncs, and a-chloroketones... 

Aluminum amalgam Methyl ketones from carboxylic acid esters via / -ketosulfoxides... 

Acylmalonic acid esters s. 11, 835 methyl ketones from carboxylic acids cf. H. Muxfeldt, B. 92, 3122 (1959)... 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

The preferred route for reducing the molecular weight of PVA involves chain scission at the 1,3-diketone site (see Fig. 6). As the diketone element is chemically not very stable, a spontaneous degradation of oxidised PVA was also discussed [80]. Nevertheless, the preferred degradation pathway is most likely the biochemical process because enzymes were identified that showed high activity with diketone substrates [81], especially with oxidised PVA. The p-diketone hydrolase (BDH EC 3.7.1.7) hydrolyses aliphatic p-diketones to form methyl ketones and carboxylic acids in equimolar amounts [82]. The enzymatic cleavage of C-C bonds in p-diketones is not well studied [83]. BDH enzymes could be isolated from different PVA-degrading strains, purified, characterised and cloned [84]. 

KETONES FROM CARBOXYLIC ACIDS AND GRIGNARD REAGENTS METHYL 6-OXODECANOATE (Oecanolc acid, 6-oxo-, nethyl ester]... 

The use of the haloform reaction for the conversion of methyl ketones into carboxylic acids (Sections 5.11.1, p. 667) is also applicable in the aromatic field. The conditions may be readily adapted from those described for the conversion of aliphatic methyl ketones into carboxylic acids (Expt 5.124). 

Ketones from Carboxylic Acids and Grlgnard Reagents Methyl 6-Oxodecanoate... 

Potassium hypochlorite, KOCI, acts like sodium hypochlorite. This reagent is prepared in situ from potassium hydroxide and chlorine and oxidizes primary alcohols to aldehydes [702] and methyl ketones to carboxylic acids [703]. 

Despite its age, the Haloform reaction remains a unique and powerful transformation of methyl ketones to carboxylic acids. The range of substrates is truly enormous. In addition to the examples shown below, the Haloform reaction has been employed to synthesize these carboxylic acids (from the corresponding methyl ketones) 3-... 

A hydrolase, named BDH, was purified from a culture broth of Pseudomonas vesicularis PD. The / -diketone moiety was hydrolytically cleaved to produce methyl ketone and carboxylic acid terminals as shown in Fig. 14.15 (Sakai et al., 1981, 1984, 1985b,c, 1986). 

Electrochemical reduction of oxazolinium salts 36 gives the anions 37, which add efficiently to alkyl halides or, in the presence of McsSiCl, to methyl acrylate, methyl vinyl ketone, and acrylonitrile. Simple acid hydrolysis then gives the ketone products 38 and 39, and this method is quite general since the starting salts are readily prepared from carboxylic acids, R C02H (87TL4411). 

In a detailed study of the reaction of methylene ketones with carboxylic acids in the presence of polyphosphoric acid, pyran-4-ones were obtained from l,3-diphenylpropan-2-one, phenylpropan-2-one and pentan-3-one (61JA193). In the first case, formation of 2,6-dimethylpyran-4-one ( 14 R = H) rather than the 2-benzyl-6-methyl-3-phenyI isomer... 

Methyl ketones from esters (12, 126).1 The reaction of a carboxylic acid or ester with CH3Li and ClSi(CH3)3 to provide a methyl ketone has been used to obtain a silyl protected (S)-3-hydroxy-2-butanone (2) from ethyl lactate (1). The addition of... 

Methyl ketones are often directly prepared from carboxylic acids by reaction with methyllithium. Other simple alkyl ketones may also be prepared in the same fashion, making this a method that should be considered whenever these substrates are required. An important demonstration of this protocol was reported by Masamune and coworkers in their synthesis of chiral propionate surrogates (Scheme 13). The ethyl and cyclopropyl ketones are important starting materials for macrolide total synthesis and have been prepared on a large scale. The overall yield for the ethyl ketone is 65% using 3.5 equiv. of ethyllithium without protection of the hydroxy group. 

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