Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Hydrazoic acid with aldehydes

The Reactions of Hydrazoic Acid with Aldehydes and Ketones. . . . 314... [Pg.307]

The reaction of carboxylic acids, aldehydes or ketones with hydrazoic acid in the presence of a strong acid is known as the Schmidt reaction A common application is the conversion of a carboxylic acid 1 into an amine 2 with concomitant chain degradation by one carbon atom. The reaction of hydrazoic acid with a ketone 3 does not lead to chain degradation, but rather to formation of an amide 4 by formal insertion of an NH-group. [Pg.251]

In 2008, Wang and Zhu s group reported the catalytic asymmetric Passerini-type reaction of aldehydes, isocyanides and hydrazoic acid with... [Pg.203]

Reaction of carboxylic acids, aldehydes or ketones with hydrazoic acid... [Pg.251]

The Schmidt reaction of ketones works best with aliphatic and alicyclic ketones alkyl aryl ketones and diaryl ketones are considerably less reactive. The reaction is only seldom applied to aldehydes as starting materials. The hydrazoic acid used as reagent is usually prepared in situ by treatment of sodium azide with sulfuric acid. Hydrazoic acid is highly toxic, and can detonate upon contact with hot laboratory equipment. [Pg.253]

There are actually three reactions called by the name Schmidt reaction, involving the addition of hydrazoic acid to carboxylic acids, aldehydes and ketones, and alcohols and alkenes. The most common is the reaction with carboxylic acids, illustrated above.Sulfuric acid is the most common catalyst, but Lewis acids have also been used. Good results are obtained for aliphatic R, especially for long chains. When R is aryl, the yields are variable, being best for sterically hindered compounds like mesi-toic acid. This method has the advantage over 18-13 and 18-14 that it is just one laboratory step from the acid to the amine, but conditions are more drastic. Under the acid conditions employed, the isocyanate is virtually never isolated. [Pg.1413]

Thus in the reaction of aldehydes with hydrazoic acid, nitriles are generated from the unprotonated form (B) and the formanilides from the protonated form (BH+) of the aldehyde. A relationship between the ratio of the concentrations of the nitrile [N] and formanilide [F] and the pKa value is given in equation 16. [Pg.330]

A similar approach started with (45)-(2 )-5-acetoxy-4-formyloxy-2-pentenal (11) or the de-formylated (4S)-(2 )-5-acetoxy-4-hydroxy-2-pentenal (12), which were prepared from tri-O-acetyl-D-glucal55. Both aldehydes added hydrazoic acid to afford, after acidic cyclization and alkylation, an almost 1 1 mixture of the 3-azido-2,3-dideoxypentoses 13 in 79% total yield from 12 and 31 % total yield from 11. The structures of the products are confirmed by their NMR spectra and by further conversion to 3 -azido-3 -deoxythymidine (AZT) and its stereoisomers, the absolute configurations of which are known. [Pg.1106]

Reaction of ketones with hydrazoic acid proceeds similarly to the Beckmann rearrangement to give amides, while aldehydes yield nitriles and formamides under analogous reaction conditions (equations 4 and 5). [Pg.798]

The reaction of aldehydes and ketones with hydrazoic acid is more difficult to interpret. If we assume that the transformation proceeds through the intermediates LXXXVIII to XCIII and XCV (which are similar to those which were proposed for the reaction of 2,4,6-trimethyl-benzoic acid with hydrazoic acid), we see that the final product should be the amide XCIII or XCV, depending upon whether an alkyl group or a hydrogen atom with a pair of electrons migrates. [Pg.68]

Several routes to 4-alkyl-2,5-dihydrooxazoles, which were not available by previous methods, have been discovered. Thermolysis of allyl a-azidoalkyl ethers (181) gives 2,5-dihydrooxazoles via triazoline intermediates <88JOC27>. The starting materials are obtained from aldehydes, allyl alcohol, and hydrazoic acid (Scheme 89). A hlorination of oxazolidines with r-butyl hypochlorite, followed by dehydrochlorination using potassium superoxide, also provides 4-alkyl-2,5-dihydrooxazoles in 40-93% yield <92TL7751>. [Pg.309]

When the Gattermann aldehyde synthesis (hydrogen cyanide-zinc chloride) is applied to some benzyl alkyl or aryl ketones, isoquinolines are formed [2268]. Application of the Schmidt reaction to tra/u-dibenzoylstilbene at a temperature slightly above that of the surroundings converts it into a 4-benzoylquinoline [2216]. Care should be exercised with the use of hydrazoic acid. The acetal... [Pg.220]

The essentially nucleophilic isocyanides react with acid-activated aldehydes and ketones in combination with a nucleophile such as water, hydrazoic acid or carboxylic acids to yield a-hydroxycarbox-amides or some of their derivatives. Such reactions are the topic of this section. [Pg.1084]

Besides water and the carboxylic acids (3), hydrazoic acid (34) is the only acid that can be combined with carbonyl compounds (4) and isocyanides (5) to form a tetrazole derivative (37), a three-component adduct, in 7-95% yield.2 -32 With sterically hindered aldehydes and ketones considerably higher yields of (36) (68-86% vs. 8-32%) are obtained by the use of aluminum azide (35) instead of (34). ... [Pg.1086]


See other pages where Hydrazoic acid with aldehydes is mentioned: [Pg.820]    [Pg.820]    [Pg.191]    [Pg.252]    [Pg.502]    [Pg.1195]    [Pg.226]    [Pg.252]    [Pg.414]    [Pg.907]    [Pg.329]    [Pg.386]    [Pg.940]    [Pg.444]    [Pg.1288]    [Pg.798]    [Pg.820]    [Pg.330]    [Pg.396]    [Pg.397]    [Pg.462]    [Pg.94]    [Pg.139]   
See also in sourсe #XX -- [ Pg.907 ]




SEARCH



Aldehydes acidity

Hydrazoic acid

With hydrazoic acid

© 2024 chempedia.info