Diazo compounds alcohols

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). ... 

Regarding carbon nucleophiles, phosphoric acids have been applied as organocatalysts in multicomponent reactions between diazo compounds, alcohols, or amines, and aldehydes, imines, or Michael acceptors [76]. Diazo compounds can be converted into the respective metallocarbenes in the presence of dirhodium (n) carboxylates complexes [77], Such intermediates can suffer a nucleophilic attack from alcohols or amines generating oxygen or nitrogen ylides that may undergo a proton shift, furnishing the respective O-H or N-H insertion products (insertion pathway. Scheme 26.14). 

The fact that practically all aromatic amines are readily converted into diazo compounds contributed greatly to Griess s success. The original method (Griess, 1858) by which he diazotized picramic acid (1.1 see Scheme 1-1) consisted of passing nitrous gases, prepared by the reduction of nitric acid with starch or arsenious acid, into an alcoholic solution of the amine. 

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... 

Carboxylic acids can be converted to esters with diazo compounds in a reaction essentially the same as 10-15. In contrast to alcohols, carboxylic acids undergo the reaction quite well at room temperature, since the reactivity of the reagent increases with acidity. The reaction is used where high yields are important or where the acid is sensitive to higher temperatures. Because of availability, the diazo compounds most often used are diazomethane (for methyl esters) ... 

Alkylation of alcohols or phenols with diazo compounds... 

Three potential routes from 14 to 2, shown in Scheme 2.6, were identified and evaluated. Option A was the original plan of preparation. Hydroboration of the carbon-carbon double bond in 14 followed by oxidation provided primary alcohol 19 (P=H). Beta-ketoester 19 was converted to the corresponding diazo compound... 

Iodorhodium(III) porphyrins generally lead to alkylrhodium(III) porphyrins (Scheme 42)398>. This is also true for the reaction with ethyl diazoacetate in the presence of HOAc or an alcohol, and the insertion product 412 (M = Rh) could not be detected, in contrast to the corresponding cobalt porphyrin. A mechanistic scheme, which includes the diverse reaction modes of metalloporphyrins towards diazo compounds, has been proposed by Callot 393,398). 

The use of copper as a catalyst in carbenoid transfer has its roots in the Amdt-Eistert reaction, Eq. 1 (3). Although the original 1935 paper describes the Wolff rearrangement of a-diazo ketones to homologous carboxylic acids using silver, the authors mention that copper may be substituted in this reaction. In 1952, Yates (4) demonstrated that copper bronze induces insertion of diazo compounds into the X-H bond of alcohols, amines, and phenols without rearrangement, Eq. 2. Yates proposal of a distinct metal carbenoid intermediate formed the basis of the currently accepted mechanistic construct for the cyclopropanation reaction using diazo compounds. 

Shortly after Perkin had produced the first commercially successful dyestuff, a discovery was made which led to what is now the dominant chemical class of dyestuffs, the azo dyes. This development stemmed from the work of Peter Griess, who in 1858 passed nitrous fumes (which correspond to the formula N203) into a cold alcoholic solution of 2-aminO 4,6 dinitrophenol (picramic acid) and isolated a cationic product, the properties of which showed it to be a member of a new class of compounds [1]. Griess extended his investigations to other primary aromatic amines and showed his reaction to be generally applicable. He named the products diazo compounds and the reaction came to be known as the diazotisation reaction. This reaction can be represented most simply by Scheme 4.1, in which HX stands for a strong monobasic acid and Ar is any aromatic or heteroaromatic nucleus. 

The catalytic activity of rhodium diacetate compounds in the decomposition of diazo compounds was discovered by Teyssie in 1973 [12] for a reaction of ethyl diazoacetate with water, alcohols, and weak acids to give the carbene inserted alcohol, ether, or ester product. This was soon followed by cyclopropanation. Rhodium(II) acetates form stable dimeric complexes containing four bridging carboxylates and a rhodium-rhodium bond (Figure 17.8). 

A Sandmeyer reaction leading to the 3-chloro derivatives was observed upon treatment of 3-diazotriazoles with aqueous hydrochloric acid [1898LA33 26JCS1729 78ZN(B)216]. 3-Diazotriazole was reduced to the parent triazole by treatment at 0°C with primary and secondary alcohols [86DIS(B) (46) 3052]. The mechanism is not clear, but the process may be envisaged as involving hydride transfer from the intermediate 244 obtained by nucleophilic addition of alcohols to the diazo compound (Scheme 70). 

The mixture of 5 and 6 can be converted to 9 by reduction, separation and then epimerization/reduction of one isomer. Alcohol 9 is then further subjected to similar procedure as for 1 to give tricyclic ether 12, through the same Cu(tfacac)2-catalyzed ylide formation/[2,3]-sigmatropic rearrangement of diazo compound 10 (Scheme 2). 

Reaction between alkoxides or arox-ides and alkyl halides (Williamson) 0-14 Reaction between alkoxides or arox-ides and inorganic esters 0-15 Alkylation of alcohols or phenols with diazo compounds 0-16 Dehydration of alcohols 0-17 Transetherification 0-19 Alkylation of alcohols with onium salts... 

Carbenoids derived from the metal catalysed decomposition of diazo compounds undergo various chemical transformations. Control of chemoselectivity by choice of the appropriate catalyst has significantly increased the synthetic viability of catalytic cyclopropanation reactions. Intermolecular reaction of unsaturated alcohols with carbenoids derived from catalytic decomposition of alkyl diazoesters has been reported by Noels and... 

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