With Acid Chlorides or Anhydrides

Earlier in this section it was mentioned that 1,2-dihydro- and 2,4-dihydropyrazol- 

4-(2-aminobenzyl)pyrazol-3-ones 40a,b in acetic anhydride for 1 h under reflux afforded pyrazol-4-yl(methyl)(phenyl)acetamides 44a,b. 

Similar reaction conditions were used for both acetylation and benzoylation of 

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Isoquinoline can be reduced quantitatively over platinum in acidic media to a mixture of i j -decahydroisoquinoline [2744-08-3] and /n j -decahydroisoquinoline [2744-09-4] (32). Hydrogenation with platinum oxide in strong acid, but under mild conditions, selectively reduces the benzene ring and leads to a 90% yield of 5,6,7,8-tetrahydroisoquinoline [36556-06-6] (32,33). Sodium hydride, in dipolar aprotic solvents like hexamethylphosphoric triamide, reduces isoquinoline in quantitative yield to the sodium adduct [81045-34-3] (25) (152). The adduct reacts with acid chlorides or anhydrides to give N-acyl derivatives which are converted to 4-substituted 1,2-dihydroisoquinolines. Sodium borohydride and carboxylic acids combine to provide a one-step reduction—alkylation (35). Sodium cyanoborohydride reduces isoquinoline under similar conditions without N-alkylation to give... 

Normal Fischer esterification of tertiary alcohols is unsatisfactory because the acid catalyst required causes dehydration or rearrangement of the tertiary substrate. Moreover, reactions with acid chlorides or anhydrides are also of limited value for similar reasons. However, treatment of acetic anhydride with calcium carbide (or calcium hydride) followed by addition of the dry tertiary alcohol gives the desired acetate in good yield. 

Benzodiazepinone A-oxides 23 are converted into rearranged 3-(acyloxy)-l H-, 4-benzodiaze-pin-2(3//)-ones 24 by treatment with acid chlorides or anhydrides.236... 

The mechanism of the condensation in Part D probably involves thioformylation of the metallated isocyanoacetate followed by intramolecular 1,1-addition of the tautomeric enethiol to the isonitrile. This thi2izole synthesis is analogous to the formation of oxazoles from acylation of metallated isonitriles with acid chlorides or anhydrides. " Interestingly, ethyl formate does not react with isocyanoacetate under the conditions of this procedure. Ethyl and methyl isocyanoacetate have been prepared in a similar manner by dehydration of the corresponding N-formylglycine esters with phosgene and trichloromethyl chloroformate, respectively. The phosphoryl chloride method described here was provided to the submitters by Professor U. Schollkopf and is based on the procedure of Bohme and Fuchs. The preparation of O-ethyl thioformate in Part C was developed from a report by Ohno, Koi/.uma, and Tsuchihaski. " ... 

The relative stability of the oxiranes to bases at room temperature allows the selective ammonolysis of carboxylic ester groups with ammonia in methanol,49 and, conversely, free hydroxyl groups may be esterified with acid chlorides or anhydrides in pyridine without affecting the oxirane ring. Hydroxyl groups may also be converted into alkyl ethers by using either the Haworth50 or the Purdie-Irvine procedure.5152... 

Azole approach. Vicinal amino-cyano groups react with acid chlorides or anhydrides, the product being a pyrimidinone, as in the reaction of the substituted isoxazole (65) (73GEP2249163). 

The typical reactions of the alcohol group include their conversion to ethers and esters by reaction with alkyl halides and with acid chlorides or anhydrides, respectively (Scheme 6.2). The benzyl ether group is readily cleaved by hydrogenolysis and is often used as a protecting group for alcohols. Primary alcohols are oxidized initially to the aldehyde and then to the carboxylic acid. 

Acetylenic ketones can be prepared in moderate yield by the reaction of acetylenic Grignard reagents with acid chlorides or anhydrides [Eq. (41) 75-78]. Alkynyl magnesium chloride reacts with acetic anhydride to give acetylenic ketones in good yield (see Table 4, entry 17). 

Treatment of urea with acid chlorides or anhydrides yields ureides. Of special... 

New syntheses, based on the condensation of a-haloketones with acid chlorides or anhydrides catalyzed by Sml2,51 or C-acylation of enoxysilanes catalyzed by a mixture of BiCl3/NaI or BiCl3/ Znl2, have been proposed (Equation (6)) 52... 

Acylation of olefins with acid chlorides or anhydrides catalyzed by Lewis acids. When performed in the presence of a saturated hydrocarbon, the product is the saturated ketone. 

Ketones are formed from pyridylzinc halides on acylation with acid chlorides or anhydrides in reactions with benzoyl chloride or benzoic anhydride, pyridyl ketones (307) are formed in moderate yields. Reactions with 3-iodoquinoline gave the 3-benzoyl derivative 308. Organostannanes may be a better choice for ketone formation (see above). 

Propene derivatives produce pyrylium salts 28 (Balaban synthesis) by a double acylation with acid chlorides or anhydrides in the presence of Lewis acids, e.g. AICI3 ... 

Acylations of the hydroxy function of the picolinic acid residue occurred readily using standard acylation procedures reaction of pristinamycin with acid chlorides or anhydrides in the presence of pyridine or triethylamine afforded the corresponding esters (15) and the use of N or 0-chlorocarbonyl reagents afforded carbamates or carbonates. 

Substituted amides are formed by the reaction of amines with acid chlorides or anhydrides ... 

The anion of a-trimethylsilyloxybenzylphosphonate reacts with acid chlorides or anhydrides to give good yields of mixtures of a-ketols in which the benzylic alcohol predominates [equation (33)]. ... 

Esters can be prepared by reaction of alcohols with carboxylic acids under acidic catalysis but can be hydrolyzed in either acid or basic solution. They can also be prepared by reaction of alcohols with acid chlorides or anhydrides. 

Mechanism of Action. Under photolysis, acidic, and electron bombardment conditions, the transformation of o-nitrobenzyl alcohol or its derivatives involves an internal redox reaction sequence followed by liberation of the deprotected alcohol or amine (eq 1). Analogously, the photorearrangement of esters of o-NBA, obtained through its reaction with acid chlorides or anhydrides, also induces an internal redox reaction (eq 2). 

Myers has documented a highly selective, comprehensive method involving the alkylation of pseudoephedrine-derived N-acyl amides (Scheme 3.27) [97, 98]. Importantly, both enantiomers of pseudoephedrine (167) are readily available as inexpensive commodity chemicals. N-Acylation of pseudoephedrine with acid chlorides or anhydrides provides the corresponding tertiary amides, such as 168, in high yields. These amides and their alkylation products often display a propensity to be crystalline, potentially simpli-... 

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