Acid chloride reagents

The seven-membered ring analog, 327, showed different properties than those observed for 324 (eq. 64).85 Complete regioselective formation of 328 was observed for the acryloyl or crotyl derivatives. In these aza-annulation reactions, the use of acid chloride reagents resulted in higher yields than the corresponding ethyl esters. 

Tin Derivatives. 5-Stannylated or 5-zincated 1-benzyloxy-l,2,3-triazole, 114 and 115, respectively, is available from the 5-lithiated species by quenching with the respective metal halide (Scheme 49). Either metal complex is a good substrate for ketone formation 116 in the 5-position with acid chloride reagents. ... 

Figure 8 Reaction of substoichiometric amounts of acid chloride reagents with dendrimers to produce the all or nothing phenomena.

Esters (a) and acid chlorides (6) readily react with Grignard reagents to give ketones, which immediately react with a second equivalent of the reagent as in (5) to give tertiary alcohols as before. 

The main use of organocadmium compounds is for the preparation of ketones and keto-esters, and their special merit lies in the fact that they react vigorously with acid chlorides of all types but add sluggishly or not at all to multiple bonds (compare addition of Grignard reagents to carbonyl groups). Some t3rpical syntheses are ... 

The reaction giving A is chloromethylation, a reliable metliod of adding a CH2OH equivalent to an aromatic ring. You may have been surprised at the use of reagent B to make an acid chloride. B is oxalyl chloride and is often used when pure acid chlorides are wanted - the other products are gases (which ). 

Sulfur tetrafluoride [7783-60-0] SF, replaces halogen in haloalkanes, haloalkenes, and aryl chlorides, but is only effective (even at elevated temperatures) in the presence of a Lewis acid catalyst. The reagent is most often used in the replacement of carbonyl oxygen with fluorine (15,16). Aldehydes and ketones react readily, particularly if no alpha-hydrogen atoms are present (eg, benzal fluoride [455-31-2] from benzaldehyde), but acids, esters, acid chlorides, and anhydrides are very sluggish. However, these reactions can be catalyzed by Lewis acids (HP, BF, etc). 

Hydride reagents Aldehyde Ketone Acid chloride Ester Carboxyhc acid Carboxyhc salt Amide... 

Acid Chloride Formation. Monoacid chlorides of maleic and fumaric acid are not known. Treatment of maleic anhydride or maleic acid with various reagents such as phosgene [75-44-5] (qv), phthaloyl chloride [88-95-9] phosphoms pentachloride [10026-13-8] or thionyl chloride [7719-09-7] gives 5,5-dichloro-2(5JT)furanone [133565-92-1] (4) (26). Similar conditions convert fumaric acid to fumaryl chloride [627-63-4] (5) (26,27). NoncycHc maleyl chloride [22542-53-6] (6) forms in 11% yield at 220°C in the reaction of one mole of maleic anhydride with six moles of carbon tetrachloride [56-23-5] over an activated carbon [7440-44-4] catalyst (28). 

Sulfosahcyhc acid is prepared by heating 10 parts of sahcyhc acid with 50 parts of concentrated sulfuric acid, by chlorosulfonation of sahcyhc acid and subsequent hydrolysis of the acid chloride, or by sulfonation with hquid sulfur trioxide in tetrachloroethylene. It is used as an intermediate in the production of dyestuffs, grease additives, catalysts, and surfactants. It is also useful as a colorimetric reagent for ferric iron and as a reagent for albumin. Table 9 shows the physical properties of sahcyhc acid derivatives. 

Other Rea.ctlons, The anhydride of neopentanoic acid, neopentanoyl anhydride [1538-75-6] can be made by the reaction of neopentanoic acid with acetic anhydride (25). The reaction of neopentanoic acid with acetone using various catalysts, such as titanium dioxide (26) or 2irconium oxide (27), gives 3,3-dimethyl-2-butanone [75-97-8] commonly referred to as pinacolone. Other routes to pinacolone include the reaction of pivaloyl chloride [3282-30-2] with Grignard reagents (28) and the condensation of neopentanoic acid with acetic acid using a rare-earth oxide catalyst (29). Amides of neopentanoic acid can be prepared direcdy from the acid, from the acid chloride, or from esters, using primary or secondary amines. 

Chlorination with Other Reagents. Chlorotoluenes can also be obtained in good yields by the reaction of toluene with stoichiometric proportions of certain Lewis acid chlorides such as inon(III) chloride, as the chlorinating agent (51). Generally, the product mixture contains /)-chlorotoluene as the principal component. Several modifications have been proposed to improve product yields (52,53). 

Acid chlorides are useful reagents, but when the pyrazole is N- unsubstituted a dimerization occurs and the diketopiperazine (254) is isolated (Section 4.04.2.3.3(x)). However, (254) reacts with many compounds as an acid chloride would, for example with amines to yield amides (67HC(22)l). The difunctional pyrazole derivative (441) affords polymers by reaction with diphenols (69RRC763). Cyanopyrazoles can be hydrolyzed to the corresponding carboxylic acids (68CB829). 

Trichloroben2oyl chloride reagent tor esteniication of acids via a mixed anhydnde, also used tor large ring iactonization with OMAP (see also Steglich-Hassner). 

Caibamates ate formed from an amine with a wide variety of reagents, of which the chloroformate is the most common amides are formed from the acid chloride. -Alkyl caibamates are cleaved by acid-catalyzed hydrolysis A/-alkylamides are cleaved by acidic or basic hydrolysis at teflux. conditions that cleave peptide bonds. 

Fmoc-N3, NaHC03, aq. dioxane, 88-98% yield.This reagent reacts more slowly with amino acids than does the acid chloride. It is not the most safe method for Fmoc introduction because of the azide. 

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