Butyl carbonate

BOC-OCH(Cl)CCl3 (1,2,2,2-tetrachloroethyl / r/-butyl carbonate, BOC-OTCE), THF, K2CO3 or dioxane, H2O, Et3N, 60-91% yield. This reagent is a cheap, distillable solid that has the effectiveness of (BOC)20. 

The BOC group has been introduced onto the imidazole nitrogen of histidine with BOCF (pH 7-8), BOCN3, MgO, and (B0C)20. ° It can be introduced onto pyrroles and indoles with phenyl /-butyl carbonate and NaH, 67-91% yield, or with NaH, BOCN3. ... 

This is a typical nucleophilic acyl substitution reaction, with the amine of the amino acid as the nucleophile and tot-butyl carbonate as the leaving group. The tor-butyl carbonate then loses C02 and gives toi-butoxide, which is protonatecl. 

Several other nucleophilic functional groups can be induced to participate in iodocyclization reactions. t-Butyl carbonate esters cyclize to diol carbonates.79... 

By adding one equivalent of alcohol to CDI at room temperature with or without base it is possible to isolate the imidazole-iV-carboxylate, which then reacts with a second mole of ROH to yield the carbonate. As in the case of alcoholysis of imidazolides, the reaction can be accelerated so effectively with catalytic amounts of NaOC2H5 or ImNa that it takes place in most cases exothermically, even at room temperature. However, tert-butyl alcohol, even when in excess, affords with CDI and base catalysis at room temperature only the imidazole-N-tert-butylcarboxylate, obviously for steric reasons. At higher temperature the carbonic ester is formed. Mixed carbonates such as ethyl benzyl carbonate or ethyl terf-butyl carbonate can be prepared with two different alcohols added sequentially.C9],[229]... 

Generation of nitrile oxides can also proceed by the action of neutral or basic reagents, for example, tert-butyl carbonate (72) or 4-(4,6-dimethoxy-l,3,5-triazin-... 

B. t-Bulyl carbazate. In a 1-1. Erlenmeyer flask are placed 388.4 g. (2.0 moles) of phenyl <-butyl carbonate and 120.2 g. (2.4 moles) of a 64% hydrazine solution (Note 6). The mixture is swirled by hand and heated on a hot plate. When the internal temperature reaches 75-80°, it then rises rapidly and spontaneously to 104—110°, the two layers forming a dear solution. The solution is allowed to cool overnight. The mixture is then diluted with 500 ml. of ether and transferred to a separatory funnel in which it is shaken vigorously for about 10 minutes with a solution prepared from 160 g. (4.0 moles) of sodium hydroxide and 1.2 1. of water. The resulting two layers are placed in a 2-1. continuous extractor and extracted for 48 hours with ether. The ether solution is dried over magnesium sulfate, and the ether is removed by distillation from a water bath. The last portions of ether are removed with the aid of a water aspirator. The residual oil is then distilled using a Claisen flask with an air bath maintained at 115-125°. After 1 or 2 drops of fore-run the carbazate is collected at 61-65° (1.2 mm.), 24d 1.4518. The yield is 235-256 g. (89-97%) (Note 7). 

Butyl carbonate 1892-4 Butyl citrate 6119 Butyl cyanide (iso) 6413... 

Butyl butyrate, 4 460 p- -Butylcafix[4]arene, 14 165 4- -Butylcalix[8]arene-p-sulfonic acid, 23 722 D-re-Butyl carbonate, physical properties, 6 306t... 

Di-ferf-butyl carbonate, molecular formula, 6 305t... 

Symmetrical and unsymmetrical carbonates have also been obtained from the reaction of chloroformates with alcohols under soliddiquid conditions [55], and the reaction of carbamoyl fluorides with alcohols produces alkyl carbamates [58]. r-Butyloxycarbonylation of alcohols and phenols is effected by trans-esterification of di-r-butyl carbonate under basic phase-transfer catalysed conditions [59]. Yields tend to be high for the reaction with the phenols (>85%), but only moderate with the alcohols (30-81%). 

Disubstituted dihydrofurans and dihydropyrans were prepared via allylic etherification [68] in a similar manner to dihydropyrroles (cf Section 9.4.6). Thus, diaste-reoisomeric ethers were generated by the reaction of cinnamyl tert-butyl carbonate with the copper alkoxide prepared from (Rj-l-octen-3-ol, depending on which enantiomer of the phosphoramidite ligand was used (Scheme 9.39). Good yields and excellent selectivities were obtained. RCM in a standard manner gave cis- and trans-dihydrofuran derivatives in good yield, and the same method was used for the preparation of dihydropyrans. 

Tert-butyl carbonates 229 can be used instead of free acids to obtain cyclic carbonates 230. The influence of the eledronic and steric properties of phosphine ligand in the catalytic system was studied and optimal behavior was observed for eledron-deficient phosphines such as P(C6F5)3 [48]. 

Rehberg, C. E. and M. B. Dixon, Mixed Esters of Lactic and Carbonic Acids n-Alkyl Carbonates of Methyl and Butyl Lactates, and Butyl Carbonates of n-Alkyl Lactates. J. Org. Chem., 1950 15, 565-571. 

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