Oxalyl chloride, 1,3-cycloaddition

Saalfrank, Hoffmann and co-workers performed a number of reactions with tetra-alkoxyallenes such as 196 (Scheme 8.47) [1, 41, 105, 114—116] and demonstrated that this class of donor-substituted allenes can serve as a 1,3-dianion equivalent of malonic acid. Treatment of 196 with cyclopropyldicarboxylic acid dichloride 197 produces 2,4-dioxo-3,4-dihydro-2H-pyran 198 through release of two molecules of ethyl chloride [115]. Similarily, the reaction of this allene 196 with oxalyl chloride gives 3-chloromalonic acid anhydride derivative 199. This intermediate is a reactive dieno-phile which accepts 2,3-dimethyl-l,3-butadiene in a subsequent [4+2] cycloaddition to afford cycloadduct 200 in good yield [116]. 

The energetic 1,3,4-oxadiazole (22) is synthesized from the reaction of the tetrazole (20) with oxalyl chloride. In this reaction the tetrazole (20) undergoes a reverse cycloaddition with the expulsion of nitrogen and the formation of the 1,3-dipolar diazoalkane (21) which reacts with the carbonyl groups of oxalyl chloride to form the 1,3,4-oxadiazole rings. 

Chen C, XI C, Jiang Y, Hong X (2005) 1,1-cycloaddition of oxalyl dichloride with dialkenylmetal compounds formation of cyclopentadienone derivatives by the reaction of 1,4,-dilithio-l,3-dienes or zirconacyclopentadienes with oxalyl chloride in the presence of CuCl. J Am Chem Soc 127 8024-8025... 

Cycloaddition of vinylketenes, produced in situ from the dehydrohalogenation of appropriately substituted unsaturated acid chlorides, with alkenes provides a convenient source of 2-vinyl-cyclobutanones. Oxidation with ruthenium(III) chloride trihydrate gave the corresponding P-oxo acid, which by treatment with oxalyl chloride and diazomethane, successively, led to the desired 2-(2-diazoacetyl)cyclobutanones. These diazo ketones are thermally labile and rearrange upon brief heating in refluxing xylene to give the spiro[cyclopropane-l,5 -furan-2 (5 i/)-ones] 2 (Table 2). ... 

Many methods have been developed for p-lactam synthesis, including cyclisation of the corresponding amino acids. The most widely used methods are two-component couplings, which occur via concerted cycloaddition or two-step mechanisms. Another simple route to 3-functionalised azetidinones is the reaction of aziridine-2-carboxylic acid sodium salt with oxalyl chloride or thionyl chloride. ... 

Preparation of Carboxylic Acid Chlorides (and Anhydrides). Oxalyl chloride has found general application for the preparation of carboxylic acid chlorides since the reagent was introduced by Adams and Ulich. Acid chlorides produced by this means have subsequently featured in the synthesis of acyl azides, bromoalkenes, carboxamides, cinnolines, diazo ketones, (thio)esters, lactones, ketenes for cycloaddition reactions, intramolecular Friedel-Crafts acylation reactions, and the synthesis of pyridyl thioethers. ... 

Triazoles are obtained via 1,3-dipolar cycloadditions between azides and al-kynes, and they are probably the most common nitrogen heterocycles prepared on solid supports via 1,3-dipolar cycloaddition. A wide variety of 1,2,3-triazoles have been prepared on solid supports, with an alkyne or azide attached to the resin. In addition, various linkers have been studied. Alkyne-functionalized alcohol was attached to the MeOPEG resin with an oxalyl chloride linkage (Scheme 11.23). Cycloaddition of alkynes with carbohydrate-derived azides gave resin-bound 1,2,3-triazoles, and reductive cleavage with sodium borohydride released the products as primary alcohols. 

In 2005, Xi and coworkers reported that 1,1-cycloaddition of oxalyl chloride with l,4-dilithio-l,3-dienes 379 or zirconcyclopentadienes 397 afford CPDNs 399 in the presence of CuCl (Scheme 6.100a), in which the carbon-carbon bond of the 1,2-dicarbonyl component cleaves during nucleophilic addition [239]. They also found that no reaction is observed when 397 is treated with isocyanates. However, multiply substituted ICPDs 400 are formed from Lewis acid-promoted reactions (BF3-Et20) by a one-pot three-component coupling process (Scheme 6.100b) [240]. 

Snider has documented a series of investigations of intramolecular cycloaddition reactions of ketenes with olefins. High diastereoselectivity was observed with substrates that incorporate a stereocenter on the tether linking the reaction partners. Treatment of 166 with oxalyl chloride and base, for example, led to the generation of a ketene intermediate that underwent cycloaddition to afford 167 (dr=90 10. Equation 13) [120]. 

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