Ethyl oxalyl chloride

A mixture of 100 ml. of water, 100 g. of potassium acetate, and 143 g. (0.98 mole) of diethyl oxalate is stirred and heated on a water 

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The ready access to compound 204 also provided efficient routes to additional monosubstituted indolo[3,2-()]carba2oles, as reaction with ethyl oxalyl chloride... 

Reaction of (S)-(+)-2-aminobutyrate hydrochloride with ethyl oxalyl chloride followed by replacing of the ethyl ester with amino alcohol, oxidation with Dess-Martin periodinate and cyclization using TFA/TFAA in acetic acid gave the cyclic product, which was further converted to the bromide. Sub-... 

A modified literature procedure [10] provided a long-term high yield manufacturing process to the oxadiazole fragment, as depicted in Scheme 6.11. Amidation of tetrazole 40 with ethyl oxalyl chloride (41) afforded intermediate 42 which was... 

Disulfuryl dilluoride, 4326 f Ethyl chloroformate, 1164 Ethyl oxalyl chloride, 1456 /V-Ethy l-/V-propylcarbamoyl chloride, 2468... 

Acyl chlorides are converted in good yield into symmetrical carboxylic acid anhydrides upon treatment with dilute aqueous sodium hydroxide at -I0°C in the presence of a tetra- -butylammonium salt [76, 77]. Yields are considerably lower when Aliquat is used. In a similar manner, chloroformates and ethyl oxalyl chloride are converted into carbonic hemi-ester anhydrides. 

Ketoester 208 derived from l-(2-nitrophenyl)-lH-pyrrole and ethyl oxalyl chloride can be selectively reduced at the keto group with zinc iodide and sodium cyanoborohydride. Further reduction of the nitro group and cyclization to lactam 209 has been accomplished by treatment with stannous chloride in refluxing ethanol (Scheme 43 (2003BMCL2195)). 

Replacement of the chlorine in 487b with isopropylamine is accomplished, then the secondary amine product is acylated with ethyl oxalyl chloride (Equation 184). Again reduction of the nitro group allows cyclization to 489 to occur <2001H(55)1963>. 

The amino group of 3-amino-6-benzylidene-6,7,8,9-tetrahydro-ll//-pyrido[2,l-b]quinazolin-ll-one was acylated with ethyl oxalyl chloride in AW-dimethylacetamide in the presence of pyridine at ambient temperature, and the amido group of compound 161 (R = H, R1 = Et) was alkylated with methyl iodide. The ester groups of compounds 161 (R = H, Me, R1 = Et) were hydrolyzed (84GEP3326511). 

The 1,3,4-oxadiazole moiety, in analogy to the 1,2,4-oxadiazole discussed in Section 11.2.5.1, has been used extensively as an ester or amide bioisostere, but also has only recently been applied as an amide replacement in actual peptide segments.1104-1071 The synthesis of the peptide surrogate 1,3,4-oxadiazole derivative 60 is shown in Scheme 18.11021 The N-protected amino acid Boc-Ala-OH (56) was coupled with ethanol to form the ester 57 which was subsequently reacted with hydrazine to form the amino acid hydrazide 58.11(1X1 The hydrazide 58 was reacted with ethyl oxalyl chloride at — 30 °C to room temperature to provide the diacylhydrazide 59. This intermediate was subsequently dehydrated with thionyl chloride in refluxing toluene to form the desired 1,3,4-oxadiazole 60 in >95% ee. Although the overall yields are only moderate, the reported enantioselectivities of the final compounds are very good (Table 4).11021... 

Ethyl oxalyl chloride (0.24 mL, 2.1 mmol) was added to a chilled (—30 °C) mixture of the hydrazide 58 (0.407 g, 2.0 mmol) and TEA (0.29 mL, 2.1 mmol) in THF. The soln was gradually allowed to warm to rt and stirred for 3h. The triethylammonium hydrochloride was filtered off, and the filtrate was concentrated. The residue was partitioned between Et20 and H20. The organic layer was extracted with sat. aq NaHC03 and 1M NaHS03, dried (MgS04), filtered, and concentrated. The crude product 59 was used in the next step without further purification. 

In the second method, ethyl oxalyl chloride is converted first into ethyl a-oxo-1 //-imidazole-1 -acetate, which is then treated with a Grignard reagent.192 The precedent for this reaction is that acylimidazolides are highly reactive towards Grignard reagents to yield ketones without further significant reaction with the carbonyl function to give tertiary alcohols.193... 

Notes. (1) Ethyl oxalyl chloride should be handled with care in a fume cupboard since it is lachrymatory. 

Ethyl chloroglyoxylate, see Ethyl oxalyl chloride, 1452 Ethyl iV-chloro-iV-sodiocarbamate, 1155 f Ethyl crotonate, 2430 Ethyl cyanoacetate, 1883... 

Disulfuryl dichloride, 4097 Disulfuryl difluoride, 4320 f Ethyl chloroformate, 1160 Ethyl oxalyl chloride, 1452 /V-Ethyl-iV-propylcarbamoyl chloride, 2462... 

Dimethylmethyleneoxosulfanenickel(O) diethylene complex, 2852 l,3-Dioxol-4-en-2-one, 1084 Disulfur dichloride, 4108 Ethyl oxalyl chloride, 1452... 

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