Diazo with alcohols

Reaction with alcohols is general for diazo compounds, but it is most often performed with diazomethane to produce methyl ethers or with diazo ketones to produce ot-keto ethers, since these kinds of diazo compounds are most readily available. With diazomethane the method is expensive and requires great caution. It is used chiefly to methylate alcohols and phenols that are expensive or available in small amounts, since the conditions are mild and high yields are obtained. Hydroxy compounds react better as their acidity increases ordinary alcohols do not react at... 

The nitrile group in 82 has been transformed into other versatile functional groups, and the derivatives so obtained have been used in the synthesis of various naturally occurring C-nucleosides and their analogs. Reduction of 82 with lithium aluminum hydride gave the amine 90 which was, in turn, transformed84 into the ureido and N-ni-troso derivatives (91-93) by treatment with nitrourea, followed by benzylation, and nitrosation.85 The diazo derivative 94, obtained by treatment of 93 with alcoholic potassium hydroxide, was a key intermediate in the synthesis of formycin B and oxoformycin B (see Section III,2,a,b). 

Alcohols Yield Ethers.—With alkalies a similar reaction does not occur, the more stable diazotates being formed (p. 591). When heated with alcohols, however, the diazo compounds act in an exactly analogous way to that with water. In this case if an aliphatic alcohol... 

The compound CigHxaNs [43, 49] has already been mentioned as the product obtained on boiling the primary diazo-compound of phenosaffranine with alcohol. Its salts have a magenta-red colour and do not fluoresce in alcoholic solution. Concentrated sulphuric acid dissolves them with a yellowish-green colour, and on dilution the colour changes through green to redj the blue phase does not occur. 

By treating chrysaniline, CJ9H15N3, with nitrous acid, two nitrogen atoms are converted into diazo-groups. On boiling the resulting diazo-compound with alcohol, phenylacridine is fonned ... 

The replacement of a diazo-group by hydrogen may be effected by other redudng agents. If, e.g., a diazo-compound is boiled with alcohol, the latter is converted into aldehyde, thus liberating two hydrogen atoms, by which the diazo-compound is reduced ... 

By boiling a diazo-compound with alcohol the reaction may take place in a different way at times the diazo-group is not replaced by hydrogen, but by the ethoxy (-OC2H5) group, thus giving rise to a phenol ether. 

Triplet sensitization of two 1,2-diaryIdiazoethanes in methanol solution gave rise to stilbenes, by intramolecular 1,2-H shifts, and ethers, by reaction of the corresponding carbenes with methanol.This method of generating the intermediate carbenes bypasses the singlet excited diazo compounds, and thus eliminates the possibility that the products arise by direct reaction of these excited species. The results go some way towards establishing that 1,2-H and 1,2-C shifts can compete with alcohol trapping of a spin-equilibrated carbene. 

The isolation of products of trapping with alcohols when the diazo compound 59 or the diazirine 60 are irradiated (cf. Section III.A.2.C and equation 76) led the authors to postulate the intermediate formation of 1-methyl-2,3,4,5-tetraphenylsilabenzene as well as the isomeric silafulvene 63, presumably formed by rearrangement of the primary carbene photoproduct128,249. 

Rhodium carboxylates. 13, 266-269 15, 278-280 16, 289-292 17, 298-302 a-Alkoxy esters. Rhodium carbenoids derived from a-diazo esters undergo O-H bond insertion in the reaction with alcohols or phenols. Low to moderate asymmetric induction from chiral esters is observed. ... 

In this way a nitro group is introduced into the ring in a position meta to the methyl radical. In order to obtain nitro-toluene from the nitrotoluidine formed in this way, the amino group present in the latter must be removed. This is accomplished by converting the amine into a diazo compound (513), and boiling the latter with alcohol, when the diazo group is replaced by hydrogen —... 

Photfrfysis of a-Diazo Carbonyl Compounds - Some recent advances in the matrix photochemistry of diazoketones, including some heterocyclic species, have been reviewed. Flash photolysis of 10-diazo-9(10//)-phenanthrenone (35) in aqueous solution led to the detection of two transient species on the pathway to the final product, fluorene-9-carboxylic acid. These were identified, from solvent isotope effects and the nature of the observed acid-base catalysis, as fluorenylideneketene (36, X = CO) and the enol of fluorene-9-carboxylic acid (36, X = C(0H)2), formed by hydration of the ketene. In related studies, fluorenylideneketene was found to react with amines to give ylides as intermediates on the route to the amide final products. The product distribution from the photochemical reactions of 2-diazo-3-oxo-5,10,15,20-tetraphenylchlorins with alcohols strongly depends on the central metal ion of the irradiated diazoketones. ... 

The reaction of isocyanates with alcohols and with water can be catalyzed by amines and by organometallic compounds. Tertiary amines, such as l,4-diazo-[2.2.2]-bicyclooctane (DABCO) or triethylamine, are particularly effective in promoting the isocyanate-water reaction, while organometallic complexes, such as dibutyltin dilaurate or stannous octoate, are very useful for catalyzing isocyanate-alcohol reactions. Numerous articles have been written on various aspects of the catalysis of isocyanate reactions and representative examples are cited in refs. 8-10. 

Dimerization Reaction. Dimerization is another commonly encountered reaction of diazo compounds. Alcohol (16) is initially transformed into diazoester (17) with compound (1) and then converted to bisdiazocarbonyl compound (18). The Intramolecular coupling of this mixed diazo compound with a catalytic amount of Rh2 (OAc)4 produces a 1 1 mixture of (19) and (20). Furthermore, treatment of (19) with a catalytic amount of iodine quantitatively converts (19) to (20) (eq 12). ... 

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