Subject acyl chlorides

The 1,3,2-dioxastannolanes are important in organic synthesis because they can readily be derived from dialkyltin oxide and 1,2-diols, as in carbohydrates the reaction can be carried out in toluene in a few minutes under microwave irradiation.387 The dioxastannolanes can then be subjected to regioselective reaction with an electrophile such as an acyl chloride (Equation (140)) or sulfonyl chloride, or an isocyanate. The acylation or sulfonation can be carried out with catalytic amounts of the dialkyltin oxide, including the recoverable (C6F13CH2CH2)2Sn0.388... 

Dechlorination of 4-chloro-6-methylthieno[2,3-d]pyrimidine 164 with zinc in ethanol and acetic acid at 80°C gave compound 165. The latter was subjected to the Reissert reaction using two equivalents each of tributyltin cyanide and acyl chloride in dichloromethane at room temperature. With benzoyl chloride the mono-Reissert adduct 166 was obtained, whereas with acetyl chloride the di-Reissert product 167 (86JHC545). 

Single acylation reactions of dianionic cuprates have already been shown in Table 4. After the acylation reactions of these cuprates with one equivalent of an acyl chloride, the resulting lithium enolates can be subjected to a second acylation or alkylation28. The first example shown in Scheme 18 demonstrates such a case, in which the second acylation using benzoyl chloride gave a triketone (Scheme 18). The second example deals with the treatment of the enolate with iodomethane, which resulted in the corresponding 2-methyl-1,4-diketone. 

The procedure shown here describes the preparation of a-silyl ketones from aldehydes and acyl chlorides. The a-silyl ketones undergo Cram addition of various nucleophiles to produce diastereoselectively p-hydroxysilanes. These compounds are then subjected directly to elimination in situ under basic or acidic conditions to produce the corresponding alkenes. 

It was also shown, that dicarbollide ions could be subjected to similar reactions with other electrophilic agents, such as acyl chlorides,14 trialkylsilyl chlorides,15 diphenyl chloro phosphine16 etc., and yield boron sigma-bonded derivatives of dicarba-wufo-unde-caborates. 

The reactions of phosgene with nitriles have been the subject a series of publications [1343,1544,2227,2228,2230] and the general reactions of acyl chlorides (including the special... 

The acetamide was shown unexpectedly to be subject to transacylation upon treatment with another acyl chloride. ... 

Having streamlined the synthesis of acyl chloride 54, the indirect preparation of methyl enol ester 51a was addressed. As previously discussed, attempts to synthesize 53a from formyl Meldrum s acid 58 had proven unsuccessful. However, Cossy and coworkers have reported the preparation of 53a via the ozonolysis of alkene 82 and subsequent use of the crude aldehyde in the total synthesis of octalactin. Thus, methyl vinyl acetate (82) was subjected to ozonolysis at —78 °C, followed by a reductive quench to provide formyl acetate 53a (Scheme 24). The crude methyl formyl acetate was acylated with acyl chloride 54, using the previously optimized conditions, to afford methyl enol ester 51a in 74% yield over two steps. This modification to the synthesis removes a further two reactions from the sequence with a formal synthesis of (—)-7-deoxyloganin (24) now achieved in 10 steps, a length more in keeping with the complexity of this target. 

These organocopper intermediates were successfully trapped with electrophiles such as allyl bromide, acyl chlorides, and diphenylchlorophosphine, but not with benzaldehyde and methyl iodide. The resulting products were subjected to in situ oxidation with elemental sulfur to form stable alkenylphosphine sulfides 353 [103]. Owing to its synthetic potential, the regioselective carbometallation of substituted ynol ethers has recentiy witnessed a renaissance [91aj. Thus, the alkynyl ethers 354 were treated under different carbocupration conditions (Scheme 10.121). 

The catalytic cycle of this NHC-catalyzed reaction originates by the addition of the NHC to the vinylketene 39, which in turn was created from the acyl chloride 43 in basic media, to afford the diene A as an intermediate (Scheme 17). The diene A and ketone 47 are subjected to hetero—Diels—Alder (HDA) cycloaddition reaction or undergoes a stepwise vinylogous aldol reaction with intramolecular cyclization to afford the zwitterionic B. The breakdown of zwitterionic B gives the dihydropyra-none 48 and recreates the NHC catalyst (Scheme 17) (2011MI1943). 

Treatment of acyl chlorides with pyridine and trifluoroacetic anhydride (TFAA) was assumed to involve generation of ketenes which can be subjected to electrophiUc attack by TFAA to afford jd-trifluoroacetylacetic acid derivatives 484. Quenching of the reactions with dienophiles resulted in construction of heterocycles 485 that clearly result from cycloaddition reactions of intermediate acylketenes generated by ehmination from 484 (Scheme 155) (1992TL1285, 1995T2573, 1995T2585). 

Preparation of Ketones. l-[(Trimethylsilyl)methyl]benzo-triazole reacts readily with acyl chlorides to provide the corresponding (benzotriazol-l-yl)methyl ketones in good yields. One example of such reactions is given in eq 1, and similar results are reported for reactions with benzoyl, acetyl, phenylacetyl, and other acyl chlorides. As shown by an example in eq 2, the benzo-triazolyl moiety in (benzotriazol-l-yl)methyl ketones is easily removed by reduction with zinc in acetic acid to provide the corresponding methyl ketones. To prepare higher ketones, lithi-ated l-[(trimethylsilyl)methyl]benzotriazole is alkylated first and then subjected to the regular reactions with acyl chlorides and zinc. Thus, in a reaction of l-[(trimethylsilyl)methyl]benzotriazole with -BuLi followed by benzyl bromide, l-[ l-(trimethylsilyl)-2-phenylethyljbenzotriazole is obtained in 81% yield. Subsequent treatment of this product with 4-methylbenzoyl chloride and then with zinc in acetic acid provides 4-methylphenyl 2-phenylethyl... 

The reaction of acyl chlorides with ammonia, primary, or secondary amines is probably the most generally applicable method of preparing amides in the laboratory. A large variey of acid chlorides are available commercially, others are readily prepared from the acids. Not only halides of carboxylic acids but also those of sulfonic and phosphonic acids and of picric acid may be converted to amides. Both aliphatic and aromatic amines may be subjected to acylation with acid halides. The reactions of aliphatic acid chlorides have been extensively reviewed [8]. 

Thus ring acylation of phenols is observed under Friedel-Crafts conditions because the presence of aluminum chloride causes that reaction to be subject to thermodynamic (equi librium) control... 

Enzymatic hydrolysis is also used for the preparation of L-amino acids. Racemic D- and L-amino acids and their acyl-derivatives obtained chemically can be resolved enzymatically to yield their natural L-forms. Aminoacylases such as that from Pispergillus OTj e specifically hydrolyze L-enantiomers of acyl-DL-amino acids. The resulting L-amino acid can be separated readily from the unchanged acyl-D form which is racemized and subjected to further hydrolysis. Several L-amino acids, eg, methionine [63-68-3], phenylalanine [63-91-2], tryptophan [73-22-3], and valine [72-18-4] have been manufactured by this process in Japan and production costs have been reduced by 40% through the appHcation of immobilized cell technology (75). Cyclohexane chloride, which is a by-product in nylon manufacture, is chemically converted to DL-amino-S-caprolactam [105-60-2] (23) which is resolved and/or racemized to (24)... 

Sulphated zirconia catalysts can be acidic or superacidic depending on the method of treatment. A variety of acid-catalysed reactions, referred to earlier in this section, can be carried out with sulphated zirconia. Yadav and Nair (1999) have given a state-of-the art review on this subject. Examples of benzylation of benzene with benzyl chloride / benzyl alcohol, alkylation of o-xylene with. styrene, alkylation of diphenyl oxide with 1-dodecene, isomerization of epoxides to aldehydes, acylation of benzene / chlorobenzene with p-chloro benzoylchloride, etc. are covered in the review. 

Because of the particular structural features of compound 4, pointed out in Section I, the D-glucofuranosyluronic halide anomers not only have inverse thermodynamic stabilities with respect to those of D-glucopyranosyl halides but also show a different behavior towards alcohols. For instance, 2,5-di-O-acyl-a-D-gluco-furanosylurono-6,3-lactone halides, which are difficult to prepare, do not react with alcohols, inasmuch as an endo approach of the reagent is inhibited.14 The /3-bromides and -chlorides, however, just like /3-D-glucopyranosyl chlorides, are subject to alcoholysis, with formation of /3-D-glucofuranosidurono-6,3-lactones.16... 

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