Halo-acids, reaction with

Cleavage reactions of various alkyl 4,6-0-alkylidene-2,3-dideoxy-2,3-epimino-hexopyranosides having the D-allo, u-manno, D-ido, and u-galacto configurations have been performed with azide anion, halo acids, and with ammonium halides. 

Fatty acids, as we might expect, undergo reactions typical of carboxylic acids (see Chapter 17). They react with LiAIH4 to form alcohols, with alcohols and mineral acid to form esters, with bromine and phosphorus to form a-halo acids, and with thionyl chloride to form acyl chlorides ... 

Already in the last century Hantzsch (155) observed that reaction of a-halo acids (127) with excess hydroxylamine leads to oximes of a-keto acids (31) as the result of an oxidation-reduction process (Scheme 28). This process, as a method of synthesis of (31), was later thoroughly studied by Barry and Hartung (156). The oxidation-reduction reaction is responsible for the fact that later attempts to obtain the title compounds (1) from (127) by this route were never efficient (81,100) although sometimes they were patented (157). 

Substitution Reactions. Reaction with nitrous acid in dilute aqueous solutions yields the corresponding hydroxy acid or in solution containing a hydrohahc acid, the corresponding a-halo acid, with inversion in many cases. 

KRdHNKE - ORTOLEVA PyndiniumSalts Formation oi kelo pyndinium salts by reaction of alpha halo katona darrvatives with pyndine and th cleavage to caiboxytic acids... 

The second general method is the aluminum halide-catalyzed reaction of acid halides with ethylene to give g-halo ketones which are subsequently converted to ketals. ... 

Bromination of the substituted butyric acid, 26, by the Hell-Volhardt-Zelinsky procedure affords the a-halo acid bromide (27). Reaction of this with urea affords directly bromisovalum (28). 

Reaction of halo sulfonic acid esters with boranes 10-125 Alcoholysis of sulfonic acid derivatives 13-15 Vicarious substitution of aryl nitro compounds... 

Thus, the reaction of alkyl halides and a-halo esters with sodium nitrite provides a very useful synthetic method for nitroalkanes and a-nitro esters. However, ethyl bromoacetate is exceptional in that it fails to give ethyl nitroacetate on treatment with sodium nitrite.93 This is due to the acidic hydrogen of the ethyl nitroacetate, which undergoes a further reaction with sodium nitrite to give the oxidized products (see Section 6.1, which discusses the Nef reaction). In a similar way, the reaction of benzyl bromide with sodium nitrite at 25 °C gives benzoic acid predominantly. To get phenylnitromethane, the reaction must be carried out at low temperature (-16 °C) (Eq. 2.48).93... 

The second method of intramolecular cyclization to 2,5-DKPs involves formation of the Ni—Ce bond. This reaction entails acylation of glycinamide with an a-halo acid halide, followed by ring closure under basic conditions. ... 

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