Hydroxymethylene compounds

In addition to previously described syntheses4-5 by diazo group transfer with deformylation,6 2-diazocyclohexanone has been prepared by two variants of this method. In one, the reaction of 2-(hydroxymethylene)cyclohexanone with -toluene-sulfonyl azide is carried out in ether/diethylamine, and an enamine is assumed to be formed as an intermediate 7 in the other, the sodium salt of the hydroxymethylene compound was treated with the lithium salt of p-carboxybenzenesulfonyl azide... 

Regioselective isomerization of these p-methylenaldehydes in Et2NH produce the compound (E Z 97/3). These synthons were synthesized by formylation of ionones and concomitant acetalysation of the sodium salts of the hydroxymethylenic compounds. Wittig reaction and acidic hydrolysis of the p-methyleneacetals produced the p-methylenealdehydes. 

S, 7R)-7,8,8- Trimethyl-4,5,6,7-tetrahydro-4,7-methano-2-indazole. A solution of 40.0 g (0.222 mole) of the hydroxymethylene compound in 250 mL of absolute ethanol in a 1-L, round-bottomed flask is treated with 20 mL (21 g, 0.42 mole) of hydrazine hydrate.5 The flask is fitted with a condenser and the solution is heated to reflux for 48 h, after which the volume is reduced to... 

The compounds separate from the condensation as sodium salts. From the simple ketones, the compound formed is not stable and undergoes change on precipitation from its sodium salt. The formation of a hydroxymethylene compound is used as proof of the presence of the group—CH2—CO—in camphor. The following preparation shows the details of the method. 

Yield.—66% theoretical (10 gms.). Colourless crystals insoluble in water M.P. 61° gives a deep violet coloration with ferric chloride and a bluish-green crystalline precipitate of copper benzoyl acetone with alcoholic copper acetate. This shows the compound to be tautomeric, a little of the enol form being present at ordinary temperatures. The acidity of the hydroxyl group in the enol form is not so marked as it is in the case of the hydroxymethylene compounds nevertheless, the metallic salts of benzoyl acetone and such di-ketones are remarkably stable, and on account of their great crystallising power have been used for the determination of the valency and atomic weight of the rare elements. They are also of importance in the modern theory of co-ordination. (C., 1900,1., 588 B., 34, 2584.)... 

Camphorquinone (249) is responsible for the yellow colour of freshly prepared 3-hydroxymethylenecamphor it is formed by oxidation, and can be made from the hydroxymethylene compound by treatment with a diamine, the resulting bis-aminomethylenecamphor being even more readily oxidized in air. ... 

The results of the Hofmann degradation show that the ethylene chain forming ring D extends from the nitrogen atom to either Ca or C3,. The formation of a hydroxymethylene compound from a-dihydrocaranone and ethyl formate eliminates the possibility of ring D attachment at the 2-position. 

Diphenyl-4-oxothiopyran-3-carboxaldehyde (100) was produced in high yield by an unusual oxidation of 4-chloro-2,6-diphenyl-2//-thiopyran-3-carboxaldehyde by Se02 as well as from the hydroxymethylene compound (Scheme 1). Numerous potentially useful conversions of reduced thiopyrans and thiopyrans have been described. ... 

Sodium acetate Japp-Klingemann reaction with hydroxymethylene compounds Hydrazones from diazonium salts... 

Since the jS-ketoaldhydes that result from acidification exist with the formyl group extensively enolized, the compounds are often referred to as hydroxymethylene derivatives. The formation of the product is governed by thermodynamic control therefore, the dominant product expected from unsymmetrical ketones can be predicted on the basis of considerations of relative stability. Once formed, hydroxymethylene compounds have several synthetic uses. A hydroxymethylene group can be converted to methyl via reaction with a mercaptan followed by reduction. ... 

The formation of 1,3-dithianes from hydroxymethylene compounds, which are enol tautomers of j3-keto aldehydes, has been shown to be useful in itself. When followed by desulphurization the net reaction is the decar-bonyladon to the ketone. This has been used to advantage in the formation of the methyl ketone (17) in equation (24). Similarly the methyl ketone (18) was formed from its hydroxymethylene derivative. ... 

A positive reaction is obtained, however, with a series of nonphenolic compounds aromatic amines, ends or hydroxymethylene compounds, tautomeric jS-diketones, j -ketoesters, derivatives of malonic acid esters or of cyanoacetate with a negative substituent at the -- CH2 group, some isonitrites, hydroxylamine derivatives, oximes, hydroxamic acids, and certain derivatives of sulfur. 

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