Tert-butyl chloroformate

C22H22C1N,0 114772-55-3) see Losartan potassium tert-butyl chloroformate (C5H9CIO2 24608-52-4) see Cefalexin 2-butyl-4-chloro-5-hydroxymethyiimidazole (CSII13CIN2O 79047-41-9) see Losartan potassium 2-butyl-4-cbloro-lif-imidazole-5-carboxaldehyde (CnHiiClNjO 83857-96-9) see Eprosartan Losartan potassium... 

C5H4N4S 4-mercapto-l H-pyrazolo[3,4-d]pyrimidine hemi 5334-23-6 25.00 1.4634 2 4482 C5H6CI402 b,b,b-trichloro-tert-butyl chloroformate 66270-36-8 25.00 1.4953 2... 

The chloroformate of the tertiary alcohol l,l,l-trichloro-2-methylpropan-2-ol 90, 2,2,2-trichloro-tert-butyl chloroformate 91 (TCBoc-Cl), is a reagent that can be used to introduce the TCBoc protective group, and is stable under acidic and basic con-... 

The next step yields 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester. L-proline tert-butyl ester (5.1 g) is dissolved in dichloromethane (40 ml) and the solution stirred and chilled in an ice bath. Dicyclohexylcarbodiimide (15 ml) is added followed immediately by a solution of 3-acetylthio-2-methylpropanoic acid (4.9 g) in dichloromethane (5 ml). After 15 minutes stirring in the ice bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate is concentrated to dryness in vacuo. The residue is dissolved in ethyl acetate and washed neutral. The organic phase is dried over magnesium suifateand concentrated to dryness in vacuo. The residue 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester is purified by column chromatography (silica gel-chloroform), yield 7.9 g. 

Likewise, synthetic 2//-azepines isomerize to 3//-azepines in refluxing chloroform (2-3 h) or in tert-butyl methyl ether at room temperature.291 The isomers can be readily separated by chromatography on silica gel, as the more basic 2//-azepines30 have lower Rf values. In contrast, 7-butyl-2//-azepin-2-acetic acid (11), obtained by heating the tert-butyl ester 10 with iodotrimethylsilane, is stabilized by intramolecular hydrogen bonding and shows no tendency to rearrange to the 3//-isomer.291... 

The configuration of the adduct with dimethyl acetylenedicarboxylate depends on the nature of the solvent used protic solvents, such as methanol or ethanol (but not tert-butyl alcohol), favor formation of (Z)-25a, whereas in nonprotic solvents, such as benzene, chloroform or acetonitrile, ( )-25a is the major product. 

Yields higher than about 70% for any of these isonitrile preparations generally indicate incomplete fractionation. The purity of the product may be conveniently checked by proton magnetic resonance spectroscopy. The characteristic 1 1 1 triplet for tert-butyl isocyanide appears at <5 1.45 (chloroform-d). A small upheld peak usually indicates the presence of unreacted amine. Other common contaminants are dichloromethane and chloroform The purity may be determined more accurately by gas chromatographic analysis on a 230 cm. by 0.6 cm. column packed with 10%SE30 on Chromosorb G, 60-80 mesh, at 80°. 

Interesting developments in simple azetidine chemistry continue to be reported. The apparently general acetylative dealkylation of Af-tert-butyl-3-substituted azetidines 6 (R = Bu ) in the presence of boron trifluoride provides a two-step route to azabicyclobutane 7 from 6 (R = Bu, R = Cl). An aqueous solution of 7 reacts with ethyl chloroformate to give 8. Relatively unexplored 3-azetidinones 9 (R = Ac or NO2) are available from 3-acetoxya2Ktidine 6 (R = Ac, R = OAc) which is obtained by acetylative dealkyation of 6 (R = Bu , R = OAc) <96JOC5453>. 3-Substituted azetidines can be utilized in the synthesis of polyfunctional y- and S-aminophosphonic acid derivatives <95TL9201>. 

The use of iodotrimethylsilane for this purpose provides an effective alternative to known methods. Thus the reaction of primary and secondary methyl ethers with iodotrimethylsilane in chloroform or acetonitrile at 25—60° for 2—64 hours affords the corresponding trimethylsilyl ethers in high yield. The alcohols may be liberated from the trimethylsilyl ethers by methanolysis. The mechanism of the ether cleavage is presumed to involve initial formation of a trimethylsilyl oxonium ion which is converted to the silyl ether by nucleophilic attack of iodide at the methyl group. tert-Butyl, trityl, and benzyl ethers of primary and secondary alcohols are rapidly converted to trimethylsilyl ethers by the action of iodotrimethylsilane, probably via heterolysis of silyl oxonium ion intermediates. The cleavage of aryl methyl ethers to aryl trimethylsilyl ethers may also be effected more slowly by reaction with iodotrimethylsilane at 25—50° in chloroform or sulfolane for 12-125 hours, with iodotrimethylsilane at 100—110° in the absence of solvent, " and with iodotrimethylsilane generated in situ from iodine and trimcthylphenylsilane at 100°. ... 

Butanetriol trinitrate tert-Butoxycarbonyl azide n-Butyl chloroformate... 

Potassium tert-butylate leads to ignition of halogen derivatives, which is more or less immediate, depending on their nature and physical state two minutes with liquid dichloromethane and gaseous chloroform one minute with liquid carbon tetrachloride and epichlorhydrin immediate ignition with gaseous chloroform. 

Reacts with vapors of sodium with luminescence at about 260°C. Reacts explosively with thionyl chloride or potassium reacts violently with hexafluoro isopropylidene, amino lithium, ammonia, and strong acids reacts with tert-butyl azidoformate to form explosive carbide reacts with 24-hexadiyn-l, 6-diol to form 2, 4-hexadiyn-l, 6-bischloro-formate, a shock-sensitive compound reacts with isopropyl alcohol to form isopropyl chloroformate and hydrogen chloride thermal decomposition may occur in the presents of iron salts and result in explosion. 

Materials. Methylene 4,4 -diphenyldiisocyanate (MDI, Mobay) was recrystallized from cyclohexane. Toluenediisocyanate (TDI— represents mixture of 2,4- and 2,6-isomers in 80/20 ratio), p-toluidine (Aldrich) and aniline (Aldrich) were purified by vacuum distillation before use. Diphenylmethane, tert-butyl peroxide (TBP), 4-bromoaniline, butyl lithium in hexane, and ethyl chloroformate, were obtained from Aldrich and used as received. Spectrograde tetrahydrofuran (THF) and benzene from Burdick and Jackson were used as received. Poly(tetramethylene ether glycol) with MW 1000 was obtained from polysciences and dehydrated under a rough vacuum at 50 °C for 24 h. 

Triazoles (386, R1 = COOMe) were treated with potassium tert-butylate in a mixture of f r/-butanol and benzene for 15-60 min to give (substituted amino)methoxycarbonylmethylenemalonates (387, R1 = COOMe) in 28-54% yields. In the case of the acetyl derivative (386, R = Ph, R1 = COMe), the reaction was carried out in chloroform in the presence of triethylamine at ambient temperature for 8 hr, to give (pheny-lamino)acetylmethylenemalonate (387, R = Ph, R = COMe) in 38% yield. (Phenylamino)acylmethylenemalonates (387, R = Ph,R = COMe, COPh) were also prepared in 62-74% yields when diazo derivatives (388, R1 = COMe, COPh) were heated in benzene for 4-24 hr (80T1821) (Scheme 34). 

Ethyl 3-oxoalkanoates when not commercially available can be prepared by the acylation of tert-butyl ethyl malonate with an appropriate acid chloride by way of the magnesium enolate derivative. Hydrolysis and decarboxylation in acid solution yields the desired 3-oxo esters [59]. 3-Keto esters can also be prepared in excellent yields either from 2-alkanone by condensation with ethyl chloroformate by means of lithium diisopropylamide (LDA) [60] or from ethyl hydrogen malonate and alkanoyl chloride usingbutyllithium [61]. Alternatively P-keto esters have also been prepared by the alcoholysis of 5-acylated Mel-drum s acid (2,2-dimethyl-l,3-dioxane-4,6-dione). The latter are prepared in almost quantitative yield by the condensation of Meldrum s acid either with an appropriate fatty acid in the presence of DCCI and DMAP [62] or with an acid chloride in the presence of pyridine [62] (Scheme 7). 

A number of nonnatural amino acids were resolved into individual enantiomers on 0-9-(2,6-diisopropylphenylcarbamoyl)quinine-based CSPby Peter and coworkers [48,90,113,114] after derivatization with Sanger s reagent, chloroformates (DNZ-Cl, FMOC-Cl, Z-Cl), Boc-anhydride, or acyl chlorides (DNB-Cl, Ac-Cl, Bz-Cl). For example, the four stereoisomers of P-methylphenylalanine, P-methyltyrosine, P-methyltryptophan, and P-methyl-l,2,3,4-tetrahydroisoquinoline-3-carboxylic acid could be conveniently resolved as various A-derivatives [113]. The applicability spectrum of cinchonan carbamate CSPs comprises also P-amino carboxylic acid derivatives, which were, for example, investigated by Peter et al. [114]. A common trend in terms of elution order of DNP-derivatized P-amino acids was obeyed in the latter study On the utilized quinine carbamate-based CSP, the elution order was S before R for 2-aminobutyric acid, while it was R before S for the 3-amino acids having branched R substituents such as wo-butyl, iec-butyl, tert-butyl, cyclohexyl, or phenyl residues. 

We shall use the data of Mato et al. [2] for the vapor pressure and vapor composition of mixtures of methyl tert-butyl ether [1] and chloroform (2) at 313.15 K to illustrate the procedures used to calculate as a function of composition. These data are plotted in Figure 17.3. 

Figure 17.4. Activity coefficients of methyl tert-butyl ether 71 and chloroform 72 as a function of at 313.15 K. Data from Ref. 2.

Clofibrate Clofibrate, ethyl ether 2-(4-chloropheoxy)-M( -butyric acid (20.2.2), is synthesized by esterifying 2-(4-chlorophenoxy)-/yo-butyric acid (20.2.1) with ethyl alcohol. This is synthesized in a single-stage reaction from 4-chlorophenol, acetone, and chloroform in the presence of an alkali, evidently by initial formation of chlorethone-trichloro-tert-butyl alcohol, which under the reaction conditions is converted into (4-chlorophenoxy)trichloro-fert-butyl ether, and further hydrolyzed to the desired acid 20.2.1, which is further esterified with ethanol in the presence of inorganic acid [6-8]. 

Flectrophilic addition of polychloroalkanes such as, e.g., chloroform or 1,1,2,2-tetrachloroethane to Cjq with AICI3 in a 100-fold excess gives the monoadduct with a 1,4-addition pattern (Scheme 8.12) [93, 94], The reaction proceeds via a CjqR cation (19, Scheme 8.12) that is stabilized by the coordination of a chlorine atom to the cationic center. The cation is trapped by Cl to give the product 20. The chloroalkyl fullerenes can be readily hydrolyzed to form the corresponding fullerenol 21. This fullerenol can be utilized as a proper precursor for the cation, which is easily obtained by adding triflic acid. The stability of CjqR is similar to tertiary alkyl cations such as the tert-butyl-cation [95],... 

To detect peptides and amino acid derivatives using the chlorine peptide spray the following procedure is carried out. Solution I (1% tert-butyl hypochlorite in cyclohexane) and solution II (1% soluble starch and 1% KI in water) are prepared. To prepare solution II starch is dissolved in boiling water first and potassium iodide is added to the cold solution. A small amount of chloroform is added to inhibit bacterial growth. 

Solvents selected were similar to the solvents that Glajch et al. [35] used for Normal Phase Liquid Chromatography. Methyl tert- butyl ether (a proton acceptor) was selected instead of ethyl ether, since the former one is less volatile. The other two selected solvents were methylene chloride (dipole interactions) and chloroform (proton donor). These three solvents meet all practical requirements. The polarity P [21] of the solvents is 2.5, 3.1 and 4.1, respectively. The solvents were used in pure form no supporting solvent was used. 

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