Homologization of ketones with

The aluminium trichloride-catalysed homologation of ketones with diazomethane has been applied to the synthesis of D-bishomo-steroids." Thus,... 

Homologation of ketones with diazoacetic esters. Under catalysis with this Lewis acid or antimony pentachloride, diazoacetic esters react with ketones to form the homologated iS-keto esters (equation I). Reactions of this type have... 

Homologization of ketones with diazo compounds from oc Diketones... 

A novel alkoxycarbonylmethylene carbon-carbon insertion process is reported to occur in the triethyloxonium fluoroborate-catalysed homologation of ketones with ethyl diazoacetate i -ketoesters are produced in high yield. Although the analogous reaction with diazoacetone does not occur, the intramolecular counterpart is successful, providing a route to polycyclic /3-diketones, e.g. the conversion of (85) into (86). 

Alkylidenes (alkylidene carbenes) are valence isomers of alkynes. They have been prepared by alkyne pyrolysis, by homologation of ketones, and by generation of alkenyl anions bearing oc-leaving groups. Generated by any of these means, an alkylidene will insert intramolecularly into a remote C- H bond to form a new C—C bond and thus a cyclopentene. A concerted two-electron process, this reaction proceeds with retention of absolute configuration at the C - H site. 

Homologaton of ketones.3 The reagent is generally superior to diazomethane for homologation of ketones, particularly alicydic ones. The reaction with fluorcnone, followed by hydrolysis, gives 9-phenanthrol in 80% yield. 

Homologation of ketones. 1 Ketones undergo homologation when treated with trimethylsilyldia/omelhane in the presence of Bl , elherate. Yields are generally superior to those obtained with dia/omcthanc Another advantage is that the... 

OL-Hydroxy aldehydes. A new method for one-carbon homologation of ketones to a-hydroxy aldehydes involves Darzens condensation with chloromethyl phenyl sulfone to give an ex,p-epoxy sulfone followed by ring opening by hydroxide ion. The anhydrous potassium hydroxide obtained by controlled addition of water to potassium /-butoxide (8,... 

The oximes of ketones with large hydrocarbon radicals like the acetyl-phenanthrenes are readily prepared by die action of hydroxylamine hydrochloride in the presence of pyridine. Special studies have been made for the synthesis of 1,2-cyclohexanedione dioxime as well as the next higher homolog. Dimethylglyoxime, CH,C(=NOH)C(=NOH)CH is... 

Two types of products are generally obtained by reaction of ketones with diazoalkanes a homologous carbonyl compound and a small amount of oxirane. The reaction scheme is presented in Eq. 85. 

Ketones.- A new synthesis of cyclopentadienes by the reactions of allylidenetriphenylphosphonium ylides (40) with a-halogenocarbonyl compounds has been reported.33 Wittig reactions of the ylide derived from the phosphonium salt (41) provide the hydrazones (42).34 This reaction combined with hydrolysis of (42) constitutes a method for the n-i-2 homologation of ketones and aldehydes (Scheme 8). 

OLy -Enals p-Keto diethylacetals, obtained by reaction of ketones with this reagent, can be converted into one-carbon-homologated a,p-enals by reduction (NaBH4) and acid-catalyzed rearrangement. 

Ketone homologation. The adducts of ketones with methoxymethy 1 phenyl sulfone... 

Emmert reaction. Formation of 2-pyridyldial-kylcarbinols by condensation of ketones with pyridine or its homologs in the presence of aluminum or magnesium amalgam. 

Reaction of ketones with lithium trimethylsilyldiazomethane 2 (Peterson olefination) to give after rearrangement the homologous alkynes. 

Alkynes. Deoxygenative homologation of ketones is accomplished simply by treatment with lithiated trimethylsilyldiazomethane. 

Homologation. The lower basicity of the anion derived from (1), compared with that of the dimethyl phosphonate, is useful for homologation of ketones containing acidic a-hydrogens, including cyclopentanone and P-tetralones. The products are ketene Jithioacetals. 

A similar transformation (Scheme 12) can be achieved by allowing the carbanion derived from a-chloroethyltrimethylsilane to react with an aldehyde or ketone to give the a/3-epoxysilane, which is readily hydrolysed to the methyl ketone. Similarly chloromethyltrimethylsilane provides aldehydes through homologation of ketones and aldehydes. Direct conversion of the intermediate epoxysilanes into the corresponding aldehyde protected as the ketal or dithioketal is also described. ... 

Although males of some species of Centris mark territories with chemicals released by the mandibular glands (Vinson et al., 1982), males of those species with enlarged hind legs use secretions applied to substrates with the hind legs. These femoral/tibial secretions contain a homologous series of ketones with pentadecanone dominating, acetates and ethyl myristate (Williams et al., 1982). 

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