Di-ferf-butyl dicarbonate

The functionalized allene, DIMETHYL 2,3-PENTADIENEDIOATE, the first in the series, is an intriguing substrate for various addition and cycloaddition reactions. Finally, a new reagent, DI-ferf-BUTYL DICARBONATE, for he formation of A-f-BOC derivatives which eliminates the use o the hazardous fert-BUTYL AZIDOFORMATE (WARNING) is intrqduced. 

To a stirred solution of cyclododecanone oxime (1 mmol) in EtOH (10 mL) were added PMHS (180 mg, 3.0 mmol), di-ferf-butyl dicarbonate (240 mg, 1.1 mmol), and 10% Pd/C (10 mg). The reaction mixture was stirred at 40-50° for 7 hours, after which time it was filtered and the filtrate concentrated under vacuum. The crude product was purified by column chromatography to give N-Boc-cyclododecylamine 80%. 

FIGURE 3.17 Reagents for protection of amino groups as the ferf-butoxycarbonyl derivatives. terf-Butyl chloroformate is rarely used because of its low boiling point. The oxime is 2-ferf-butoxycarbonyloximino-2-phenylacetonitrile,45 Boc20 = di-ferf-butyl dicarbonate, or di-terf-butyl pyrocarbonate.46 (Tarbell et al., 1972 Pozdvev, 1974). Acylations are carried out at pH 9 to avoid dimerization. 

In a 50 mL round-bottomed flask equipped with a magnetic stir bar were placed 5 (454 mg, 1.0 mmol), di-ferf-butyl dicarbonate (267 mg, 1.2 mmol), A,A-diisopro-pylethylamine (260 mg, 2 mmol) and dichloromethane (20 mL). The solution was stirred at room temperature for 4h. The resulting solution was washed with 5 % aq. HCl. The organic phase was separated, dried over anhydrous sodium sulfate and... 

Starting from the commercially available (+)-3-carene, the cycloaddition of chlorosulfonyl isocyanate [228] has been reported to furnish the enantiomeric (3-lactam in a regio- and stereoselective manner [229]. Treatment of the (3-lactam with di-ferf-butyl dicarbonate resulted in iV-Boc (3-lactam, that could be readily opened under mild conditions (Scheme 104). 

In amino acid and peptide chemistry, the di-ferf-butyl dicarbonate (BocaO) is an extensively used reagent for the clean and rapid Boc-protection of amine functionalities.It is also an efficient ferf-butoxycarbonylating agent for alcohols, thiols, and carbon nucleophiles, and it has been used for the conversion of amines into isocyanates, carbamates, and urea derivatives.The reaction of amino acids with chloroformates to produce N-urethane-protected amino acids if not performed under optimal conditions is accompanied by the formation of N-protected oligomers this has been well documented in the case of and... 

Predict the product of the reaction of valine with the following reagents (a) CH3CH2OH, acid (b) Di-ferf-butyl dicarbonate... 

A number of reagents have been developed to meet these requirements. Three that are often used are benzyl chloroformate, di-ferf-butyl dicarbonate (sometimes abbreviated B0C2O, where Boc stands for rert-butyloxycarbonyl), and 9-fluorenylmethyl chloroformate ... 

Di-ferf-butyl dicarbonate is a low-melting solid that is a liquid at or near room temperature and hydrolyzes readily to give ferf-butyl alcohol and carbon dioxide. Wear latex gloves when handling this chemical and do not breathe it or allow it to come in contact with your skin. If contact occurs, immediately flood the affected area with cold water and then rinse with 5% sodium bicarbonate solution. Dispense di-ferf-butyl dicarbonate only at a hood and minimize its exposure to atmospheric moisture by keeping the bottle tightly closed when not in use. 

Set-Up and Reaction Place 0.90 g of L-alanine in a 50-mL round-bottom flask containing a stirbar. Add 5 mL of a 3 A/f solution of aqueous sodium hydroxide and 5 mL of fert-butyl alcohol to the round-bottom flask and stir the mixture until all of the solids have dissolved. With continued stirring, add 2.5 mL of di-ferf-butyl dicarbonate and then stir the reaction mixture for 45 min at room temperature. 

A detailed review on the reactions of di-ferf-butyl dicarbonate (B0C2O), in conjunction with 4-dimethylaminopyridine (DMAP), with amines and alcohols has been given by Hassner and Basel [664]. Many general procedures for reactions of B0C2O with common alcohols 930 are presented therein. In most cases, either O-Boc derivatives 933 and/or symmetrical carbonates 934, or mixed 931 and/or symmetrical carbonic-carbonic anhydrides 932 are formed. 

In the first group, primary amines are reacted with carbonyl insertion compounds such as phosgene [727, 729], and sometimes phosgene substitutes such as triphosgene [507], various carbonates [503, 730, 731], bis(4-nitrophenyl)carbonate [503], di-ferf-butyl dicarbonate [664], S,S-dimethyl thiocarbonate [577], and N,N -carbonyldiimidazole [732], l,l-carbonylbis(benzotriazole) [728], and trihaloacetyl chlorides. Most of these compounds have been utilized as safer reagents that can be stored and handled without special precautions. 

The reagent most often used to protect the amino group of an amino acid is di-terf-butyl dicarbonate. Notice that the amino group rather than the carboxylate group of the amino acid reacts with di-ferf-butyl dicarbonate because the amino group is a better nucleophile. When glycine reacts with d/-terf-butyl dicarbonate in an addition-elimination reaction, the anhydride bond breaks, forming CO2 and tert-butyl alcohol. 

Write the mechanism for the reaction of an amino acid with di-ferf-butyl dicarbonate. 

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