A-Chloroacyl chlorides

Chlorine may be placed on the a-carbon of a side chain on the oxadiazole ring by allowing an amidoxime to react with an a-chloroacyl chloride.11,37 The chloromethyl group in 64 has reactivity of the order of... 

The three most important reactions for generating ketenes are the base-mediated dehydrochlorination of acyl chlorides, the dehalogenation of a-chloroacyl chlorides, and the transformation of a-diazoketones. These three methods have been explored under microwave conditions. 

Phenyl trifluoromethylketen, obtained by zinc dechlorination of the appropriate a-chloroacyl chloride, (itself derived from a-trifluoromethylmandelic acid), has found use as a reagent for the stereoselective acylation of chiral secondary... 

The Stolle Oxindole Synthesis (the Stolle Reaction) " refers to the conversion of a-chloroacyl chlorides (1) to oxindoles (3) in the presence of a Lewis acid. The reaction occurs via amide formation and subsequent annulation via an intramolecular Friedel-Crafts alkylation. 

From 1913 to 1930, R. Stolle published several manuscripts describing the synthesis of oxindoles from anilines and a-chloroacyl chlorides. His typical substrates were chloroacetanilides or the corresponding MA -diphenylamide. The manuscripts also described the synthesis of isatines (2,3-dioxindoles) from arylamines and oxalyl chloride. The reactions require high temperatures (typically > 150 °C) to complete the cyclization step. 

Reductive dechlorination of a-chloroacyl chlorides by zinc or the zinc-copper couple is frequently used in ketene chemistry.243 Sonochemical improvements minimizing side reactions were found (p. 345).244 Ordinary zinc can be used, and... 

The placement of a nitrogen atom directly on the benzilic carbon atom is apparently consistent with antispasmodic activity. Esterification of 2 (iV-piperidyl)ethanol by means of chloroacyl chloride (68) gives the basic ester (69). Displacement of the remaining halogen by piperidine gives dipiproverin (70). ... 

Carbonylation-Decarbonylation. These reactions constitute a large and important segment of the homogeneous catalytic literature. Catalysis by most of the group VIII noble metals has been found, and a variety of substrates have been converted. For example, olefins react with CO and PdCl2 or (< 3P)2PdCl2 to yield -chloroacyl chlorides (58) and unsaturated acyl chlorides (59), respectively, a, w-Dienes, such as... 

The following mechanism was proposed for the carbonylation of olefin-palladium chloride complex (10). The first step is coordination of carbon monoxide to the complex. Insertion of the coordinated olefin into the palladium-chlorine bond then forms a -chloroalkylpalladium complex (IV). This complex undergoes carbon monoxide insertion to form an acylpalladium complex (V), as has been assumed for many metal carbonyl-catalyzed carbonylation reactions. The final step is formation of a )8-chloroacyl chloride and zero-valent palladium by combination of the acyl group with the coordinated chlorine. 

The overall reaction and product stoichiometries for the degradation of chloroalkene substrates by O2 - in DMF are summarized in Table 7-1.20 Within the limits of a reaction time of 10 min or less, chloroethene, frflws-1,2-dichloroethene, Aldrin, and Dieldrin are not oxidized by O2 - in DMF. A reasonable mechanism for these oxidations is an initial nucleophilic addition of superoxide to the chloroalkenes [e.g., tetrachloroethene (Scheme (7-7)]. Subsequent loss of chloride ion would give a vinyl peroxy radical, which can cyclize and decompose to a chloroacyl radical and phosgene. t These would undergo subsequent facile reactions with O2 - to give bicarbonate and chloride ions. 

The first report of the oxidative carbonylation is reaction of alkenes with CO in benzene in the presence of PdCl2 to afford the /3-chloroacyl chloride 135 (path a) [14,55],... 

As early as 1963, Tsuji and colleagues described the reaction of olefin-palladium chloride complexes with CO to produce jS-chloroacyl chlorides [1,2]. Both internal and terminal aliphatic olefins were transformed into the corresponding chloroesters when the reaction was conducted in alcohols. Later on, in 1969, Yukawa and Tsutsumi reported on the reaction of a styrene-palladium complex with CO in alcohols [3]. Here, various cinnamates and phenylsuccinates were synthesized. Compared with Tsuji s work, they proposed a different reaction mechanism. They assumed that the oxidative addition of the alkyloxycarbonyl groups into styrenes is the key step, but a stoichiometric amount of palladium was stiU necessary to perform the reaction. Another version of a dialkoxycarbonylation of olefins was reported by Heck [4], using mercuric chloride as additive. 

Oxidative Carbonylation of Alkenes. Oxidative carbonylation of alkenes with PdCl2 in benzene affords /3-chloroacyl chlorides (eq 26). Oxidative carbonylation of alkenes in alcohol affords a,/3-unsaturated esters and 8-aIkoxy esters by monocarbonylation and succinate derivatives by dicarbonylation (eq 27). ... 

Chloroacylation of terminal aryl, alkyl or alkenyl alkynes [Le. the addition of RC(=0)-C1 across the CC triple bond] with aromatic acyl chlorides was catalysed by [IrCl(cod)(lPr)] (5 mol%) in good conversions (70-94%) in toluene (90°C, 20 h). Z-addition products were observed only, hitemal alkynes were umeactive. Surprisingly, a phosphine/[lr(p-Cl)(l,5-cod)]2 system under the same conditions provides decarbonylation products (Scheme 2.34) [117]. 

Oxalyl chloride yields COCl radicals on photolysis and this reaction has been used to directly substitute alkanes with the chloroacyl group (equation 30). Similarly, biacetyl reacts with alkanes in a benzoyl peroxide-initiated chain reaction to give ketones in ca. 60-70% yield (equation Cyanogen... 

If nucleophilic attack is slowed down by steric hindrance, for example in the formation of a trans decalin system (Table 13, entry 17)14, stereoscrambling can occur but otherwise complete retention of configuration is observed (Table 13, entries 15, 16 and 18). The starting material is readily available by palladium-catalyzed 1,4-chloroacylation of 1,3-dienes followed by chemo- and stereoselective substitution of the allylic chloride. 

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