Diazo compounds, alkylation acids

S-Alkylation with diazo compounds Dithiocarboxylic acid esters s. 19, 683 SH -> SR... 

Research into the mechanism of diazotization was based on Bamberger s supposition (1894 b) that the reaction corresponds to the formation of A-nitroso-A-alkyl-arylamines. The TV-nitrosation of secondary amines finishes at the nitrosoamine stage (because protolysis is not possible), but primary nitrosoamines are quickly transformed into diazo compounds in a moderately to strongly acidic medium. The process probably takes place by a prototropic rearrangement to the diazohydroxide, which is then attacked by a hydroxonium ion to yield the diazonium salt (Scheme 3-1 see also Sec. 3.4). 

Reagents that provide UV adsorptive derivatives of carboxylic acids are fairly numerous. The preparation of the simple benzyl esters by reacting the carboxylic ion with alkyl halides or diazo compounds has been unsuccessful due to their having unacceptable toxicity. The... 

Alkylation of Carboxylic Acids With Diazo Compounds... 

The reaction of diazo compounds with amines is similar to 10-15. The acidity of amines is not great enough for the reaction to proceed without a catalyst, but BF3, which converts the amine to the F3B-NHR2 complex, enables the reaction to take place. Cuprous cyanide can also be used as a catalyst. The most common substrate is diazomethane, in which case this is a method for the methylation of amines. Ammonia has been used as the amine but, as in the case of 10-44, mixtures of primary, secondary, and tertiary amines are obtained. Primary aliphatic amines give mixtures of secondary and tertiary amines. Secondary amines give successful alkylation. Primary aromatic amines also give the reaction, but diaryl or arylalkyl-amines react very poorly. 

Alkylation of carboxylic acids with diazo compounds... 

Two methods for converting carboxylic acids to esters fall into the mechanistic group under discussion the reaction of carboxylic acids with diazo compounds, especially diazomethane and alkylation of carboxylate anions by halides or sulfonates. The esterification of carboxylic acids with diazomethane is a very fast and clean reaction.41 The alkylating agent is the extremely reactive methyldiazonium ion, which is generated by proton transfer from the carboxylic acid to diazomethane. The collapse of the resulting ion pair with loss of nitrogen is extremely rapid. 

Protected 6-amino-hexahydro-l,7-dioxopyrazolo[l,2-4]pyrazole-2-carboxylic acid 274 is available by a thermolytic decomposition of diazo compound 273 via the Wolff rearrangement. The starting compound is simply available by alkylation of racemic 272 with the corresponding bromoacetoacetate and subsequent diazo transfer reaction (Scheme 35) <1996TL4891>. 

Acceptor-monosubstituted diazomethanes can be further converted into other types of diazo compound. C-Acylation of diazoacetic esters generally requires very reactive acylating agents, such as acid chlorides [969,970] or bromides [971]. C-Alkylations of acyldiazomethanes are best accomplished by metallation followed by treatment with a carbon electrophile [972-977], C-alkylation can also occur without any base if sufficiently electrophilic aldehydes or ketones are used [973,978 -982] or if the alkylation proceeds intramolecularly [983]. 

In 2007, Maruoka et al. introduced chiral dicarboxylic acids consisting of two carboxylic acid functionalities and an axially chiral binaphthyl moiety. They applied this new class of chiral Brpnsted acid catalyst to the asymmetric alkylation of diazo compounds withA-Boc imines [91]. The preparation of the dicarboxylic acid catalysts bearing aryl groups at the 3,3 -positions of the binaphthyl scaffold follows a synthetic route, which has been developed earlier in the Maruoka laboratory [92]. 

Alkylation of Carboxylic Acids with Diazo Compounds Hydro,acyloxy-de-dlazo-bisubstitution... 

Alcoholysis of trihalides 0-6 Hydrolysis of ortho esters 0-20 Alcoholysis of acyl halides 0-21 Alcoholysis of anhydrides 0-22 Esterification of carboxylic acids 0-23 Transesterification 0-24 Alkylation of carboxylic acid salts 0-25 Cleavage of ethers with anhydrides 0-26 Alkylation of carboxylic acids with diazo compounds... 

Alkyldiazonium Ions. The intermediacy of alkyldiazonium ions in a variety of organic reactions is well established.450 152 They are common intermediates in the acid-catalyzed decomposition of diazo compounds and the nitrous acid-induced deamination of aliphatic primary amines. The evidence for RN2+ (R = alkyl) intermediates come from both rate data and product analysis studies. However, direct investigation of alkyldiazonium ions has been difficult due to their instability. 

You met diazonium salts in Chapter 23. Arene diazonium saits are stabie compounds, but alkyl diazonium saits, whlph are formed by protonation of diazo compounds, are not. They decompose rapidiyto carbocations—this was how the carboxyiic acid got methylated at the beginning of... 

The thioesters (70) are available both by action of alkyl halides upon the corresponding dithiols (72), and by alkylation with diazo compounds.18 They are not attacked by hot dilute sodium hydroxide, but dissolved in hot acids giving yellow solutions from which they are precipitated unchanged on dilution with water. On the reactivity see Refs. 14, 15, 17, and 125. 

For example, unbranched aliphatic acids with an even number of carbon atoms will be generously represented, while one finds a nearly complete absence of odd-numbered and branched acids. Nature produces an incredible diversity of the most ingeniously constructed cyclic products containing cycloaliphatic, aromatic, or heterocyclic moieties, but such derivatives like aniline or thiophe-nol, as well as plethora of other simple representatives of these classes, are not in the list of naturally occurring substances. Such important types as alkyl halides, nitro compounds, and diazo compounds would be sparsely represented by very rare (if any) examples. Even the simplest compounds like formaldehyde, chloroform, diethyl ether, dioxane, etc., which are trivial to organic chemists, turn to be rather exotic for Nature. In the list of items provided by Nature one will notice the almost complete absence of various organometallic compounds, as well as many other classes of structures of immense scientific and practical significance. 

Finally, we note that deamination could in principle be achieved by generating an aliphatic diazonium ion in the presence of a hydride source this could lead to an alkane either via the diazene, or by Sn2 attack with loss of N . Protonating an aliphatic diazo compound, or treating an /V -alkyl, N -aryltriazene with protic or Lewis acid in the presence of a suitable reducing agent (NaBHsCN, NaBH(OAc)3 or RsSiH) might achieve this transformation. 

Diazo Esters.—Before taking up the reactions of decomposition of diazo compounds there is one other class of derivatives which should be mentioned. As an acid compound benzene diazo hydroxide yields esterSy not by the direct action of alcohols, but by the action of alkyl halides upon silver diazotate. These esters are stable compounds like... 

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