Di-tert-butyl dicarbonate

Indole (10mmol) was added to dry CH3CN (20 ml) and the mixture stirred while DMAP (122 mg, 1,00 mmol) and di-tert-butyl dicarbonate (2.62 g. 12 mmol) were added. Evolution of gas was noted and stirring was continued... 

B. Di-tert-butyl dicarbonate. A solution of 20.0 g. (0.076 mole) of di-i-butyl tricarbonate in 75 ml. of carbon tetrachloride is placed in a 600-ml. beaker fitted with a magnetic stirrer, and 0.10 g. (0.0009 mole) of freshly sublimed l,4-diazabicyclo[2.2.2]octane (DABCO) is added (Note 9). Rapid evolution of carbon dioxide begins at once. The reaction mixture is stirred at 25° for 45 minutes to complete the loss of carbon dioxide (Note 10), and then 35 ml. of water, containing sufficient citric acid to make the aqueous layer slightly acidic, is added. The layers are separated and the organic layer is dried over anhydrous magnesium sulfate and then concentrated at 25° with a rotary evaporator. The residual liquid is distilled under reduced pressure to separate 13.3-15.1 g. (80-91%) of di-butyl dicarbonate as a colorless liquid, b.p. 55-56° (0.15 mm.) or 62-65° (0.4 mm.) n T> 1.4071-1.4072 (Note 11). 

Di-tert-butyl dicarbonate and 4-dimethylaminopyridine were purchased from Alfa-Aesar Chemical Company and used without further purification. 

Triturating with diethyl ether was found to be necessary to successfully remove residual di-tert-butyl dicarbonate and di-tert-butyl iminodicarboxylate which may be produced as a result of residual traces of ammonia from step A. 

Certain reagents promote ring opening and subsequent cyclization to give other heterocycles. For example, di-tert-butyl dicarbonate induces the stereoselective ring transformation of N-alkyl aziridines 159 into oxazolidin-2-ones 160 <96TET2097>. 

N-Substituted pyrrolidines were subjected to catalytic transfer hydrogenolysis affording pyrrolidines, but the yields were low. However, when di-tert-butyl dicarbonate was added to the N-substituted pyrrolidines before catalytic hydrogenolysis, the N-Boc derivatives were all formed in good yield (Scheme... 

For example, the reaction of nitroalkanes with di-tert-butyl dicarbonate, (B0C)20, and 4-dimethylaminopyridine (DMAP) as catalysts in the presence of dipolarophiles at room temperature affords cycloadducts in improved yields compared with the Mukaiyama-Hosino method.58 The conversion of Eq. 6.32 gives a 90% yield by this procedure, whereas the conventional method using PhNCO gives a 79% yield of the same product. An additional advantage of this new method is that the use of (B0C)20 allows the reaction to be carried out with substrates that contain NH or OH groups without prior protection. The cycloaddition leads directly to protected N- or (9-Boc products (see Eq. 6.33). 

Boc-Glyctne tert-butyl ester can be prepared by treatment of glycine teit-butyl ester hydrochloride (Aldrich Chemical Company, Inc.) with di-tert-butyl dicarbonate (Fluka Chemical Corporation) and triethylamine in THF.2... 

Di-tert-butyl dicarbonate Formic add, oxydi-, di-tert-butyl ester (8) Dicarbonic acid, bis(l,l-dimethylethyl)ester (9) (24424-99-5)... 

Amino group protection may be achieved by converting the amine into its Al-tert-butyloxycarbonyl (tBOC or just BOC) derivative, by reaction with di-tert-butyl dicarbonate. This reagent should be considered as a variant of a carboxylic acid... 

The individual amino acid building blocks are first incubated with di-tert-butyl dicarbonate, thus forming a tert-butoxycarbonyl amide (BOC) amino acid derivative. 

The functionalized allene, DIMETHYL 2,3-PENTADIENEDIOATE, the first in the series, is an intriguing abstrate for various addition and cycloaddition reactions. Jinally, a new reagent, DI-tert-BUTYL DICARBONATE, for he formation of N-t-BOG derivatives which eliminates the use o the hazardous BUTYL AZIDOFORMATE (WARNING) is introjduced. 

To a solution of ketone 7 (2.56 g, 10.5 mmol) and di-tert-butyl dicarbonate (2.75 g, 12.6 mmol) in freshly distilled tetrahydrofuran (32 mL) under nitrogen... 

Di-tert-butyl dicarbonate was purchased from the Acros Chimica or Aldrich Chemical Company, Inc., and used without purification. 

The original Garner preparation3 of 5 involves the conversion of serine into the protected methyl ester 3 and controlled reduction of the latter by DIBAL. The reaction sequence employed for the preparation of 3 involves the protection of the amino acid as N-Boc derivative using di-tert-butyl dicarbonate, esterification with methyl iodide or diazomethane, and acetonization with 2,2-dimethoxypropane under acid catalysis. The N-Boc methyl serinate and the ester 3 require purification by vacuum distillation or chromatography. In a modification to this procedure reported by McKillop,2 the esterification reaction of serine is carried out first by methanol/acetyl chloride. The resulting ester is then converted into the N-Boc derivative 2 with di-tert-butyl dicarbonate and the latter transformed into 3 by acetonization. This procedure avoids... 

A 4-L, four-necked, round-bottomed flask, equipped with an efficient stirrer, a dropping funnel, reflux condenser, and thermometer is charged with a solution of 44 g (1,1 mol) of sodium hydroxide in 1.1 L of water. Stirring is initiated and 165.2 g (1 mol) of L-phenylalanine (Note 1) is added at ambient temperature, and then diluted with 750 mL of tert-butyl alcohol (Note 2). To the well-stirred, clear solution (Note 3) is added dropwise within 1 hr, 223 g (1 mol) of di-tert-butyl dicarbonate (Note 4), A white precipitate appears during addition of the di-tert-butyl dicarbonate. After a short induction period, the temperature rises to about 30-35°C. The reaction is brought to completion by further stirring overnight at room temperature. At... 

For the simultaneous protection of the thiol and amino functions of cysteine, Kemp and Carey116 first prepared a thiazolidine ring which was converted to its Boc derivative using di-tert-butyl dicarbonate in the presence of DIPEA [Scheme 8.47]. The conditions were critical because thiazolidines substituted at the 2-position are very susceptible to alkaline hydrolysis,... 

Commercial reagent-grade ethyl acetate was used as received. Ethyl acetate is best choice of solvent with regard to reaction time. Alcohols such as methanol or ethanol should be avoided because di-tert-butyl dicarbonate is decomposed by these solvents. 

Di-tert-butyl dicarbonate (97% pure) was purchased from Wako Pure Chemical Industries, Ltd. (Japan) and used as received. 

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