Isobutyl chloroformate

An isobutyl carbonate was prepared by reaction with isobutyl chloroformate (Pyr,... 

Isobutyl chloroformate [543-27-1] M 136.6, b 123-127 /atm, 128.8 /atm, d 1.053, n 1.4070. It can be dried over CaCl2 and fractionated at atm press while keeping moisture out. Its purity can be checked by conversion to the phenyl urethane derivative with PhNCO [Saunders et al. J Am Chem Soc 73 3796 7957.] IR v 1780cm [Thompson and Jameson Spectrochim Acta 13 236 7959 Rose Justus Liebigs Ann Chem 205 227 1880]. 

An isobutyl carbonate was prepared by reaction with isobutyl chloroformate (Pyr, 20°, 3 days, 73% yield), to protect the 5 -OH group in thymidine. It was cleaved by acidic hydrolysis (80% AcOH, reflux, 15 min, 88% yield). ... 

This is a very general and mild method for the preparation of amides, applicable to large structural variations in both the acid and the amine. A variety of chloro-formates can be employed, but isobutyl chloroformate is used most often. The solvent is not critical, but generally, THE is used. 

D-Phenylglycine 7-Amino-cephalosporanic acid Isobutyl chloroformate... 

A 0.60 g portion of N-carbobenzoxy-D-phenylglycine is dissolved in 10 ml of dry tetra-hydrofuran. The solution is cooled in an ice-salt bath, and to it is added 0.29 ml of tri-ethylamine with stirring over a period of 10 minutes, followed by 0.29 ml of isobutyl chloroformate, after which stirring is continued for 10 minutes at -5°C. During this time,... 

Methoxy-5-methylsulfonylbenzoic acid Isobutyl chloroformate N,N-diethylethylenediamine... 

Iron tricarbonyl dieme complex, 57, 16 Isobutyl chloroform.ate, 59, 165 Isobutylene, 59, 164 Isobutyl fluoride, 5, 73 Isobutyryl chloride, 59, 29 Isocyanato acid chlotrides, from amino acids, 59, 200... 

Isobutyl chloroformate Formic acid, chloro-, isobutyl ester (8) Carbonochloridic acid, isobutyl ester (9) (543-27-1) S-tcrf-Butyl-L-cysteine ferf-butyl ester L-Cysteine, S-(l,l-dim-ethylethyl), 1,1-dimethylethyl ester (9) ( —) acetate (38024-19-0) hydrochloride (2481-11-0)... 

Like the carbodiimide method, the mixed anhydride method results in an amide complex (Table 5, Figure 17). The acid-containing hapten is dissolved in a dry, inert, dipolar, aprotic solvent such as p-dioxane, and isobutyl chloroformate is added with an amine catalyst. The activated mixed anhydride is chemically stable and can be isolated and characterized. The aqueous protein solution is added to the activated acid and the pH is maintained at around 8.5. A low temperature (around 10 °C) is necessary during the reaction to minimize side reactions. 

H Nedev, H Naharisoa, T Haertle. A convenient method for synthesis of Fmoc-amino acidp-nitroanilides based on isobutyl chloroformate as condensing agent. Tetrahedron Lett 34, 4201, 1993. 

The triethylamine salt of 7-aminocephalosporanic acid (1605) was acy-lated at -5°C with anhydride 1606, prepared from diethyl (carboxymeth-ylamino)methylenemalonate and isobutyl chloroformate in the presence of triethylamine at -15°C, to give compound 1607 in 62% yield (74GEP2362978). 

Mixed anhydrides. Ethyl chloroformate and isobutyl chloroformate are the reagents most often used. 

The reactions of A -BOC-protected a-amino acids 424 and diazomethane in the presence of iV-methylmorpholine-polystyrene and isobutyl chloroformate resulted in formation of diazoketones 425, which, on treatment with indium(lll) triflate, were cyclized to 4-substituted-tetrahydro-l,3-oxazine-2,5-diones 426 in high overall yields (Scheme 82) <2006TL7969>. 

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