Ethyl chloroformate triethylamine

Ethyl chloroformate Triethylamine Thioacetic acid Palladium on carbon Zinc... 

A total synthesis for 3,14-dihydroxy isomorphinans from 4a-(2-aminoethyl)-l,2,3,4,4a,9-hexahydro-6-methoxyphenanthrene (34, Scheme 3.5) has been published/116) The urethane epoxide (116) was given upon treatment of 34 with ethyl chloroformate-triethylamine, followed by m-chloroperbenzoic acid oxidation. During base treatment, regioselective opening of the epoxide occurred with concomitant piperidine ring formation to 117. 

Since N-acylation is a reversible process, it has allowed the regiospecific alkylation of imidazoles to give the sterically less-favored derivative, i.e., the 1,5-disubstituted derivative (e.g., 109 Scheme 22). ° The sequence followed is (1) acylation (2) alkylation (often with oxonium reagents) and (3) deacylation with alcohol, water, or base. The N-acylation of 2-substituted imidazoles using ethyl chloroformate, triethylamine, and acetonitrile gives JV-alkoxycarbonylimidazoles ° which can lose carbon dioxide to give the JV-alkyl derivatives. The reaction is of limited use in the synthesis of asymmetrically substituted imidazoles since, whereas 2-ethyl-4-methylimidazole gave >95% of l-carbethoxy-2-ethyl-4-methylimidazole, the subsequent decarboxylation afforded a 3 1 mixture of 1,2-diethyl-4-methyl and l,2-diethyl-5-methyl compounds. 

Ethyl chloroformate/triethylamine Expansion of N,N-heterocycles via bridgehead lactams Elimination of N-methylene bridges... 

Ethyl chloroformate/triethylamine Carboxylic acid amides from carboxylic acids via carboxylic alkoxyformic anhydrides... 

Cotter et have examined the dehydration of iV-alkylmaleamic acids and observed that isomaleimide was the product when using either ethyl chloroformate/triethylamine or A,A -dicyclohexylcarbodiimide (DCC). 

Ethyl chloroformate/triethylamine Carboxylic alkoxyformic anhydrides as acylating agents... 

Ethyl chloroformate/triethylamine Carboxylic acid aryl esters from carboxylic acids and phenols... 

Ethyl chloroformate triethylamine Carbalkoxydiurethans from carboxylactams via azidocarbonyl-N-carbalkoxylactams Thiophene derivs. 

Isothiocyanates are readily made by reaction of a primary aromatic amine with carbon disulfide/triethylamine followed by ethyl chloroformate/triethylamine and by treatment of the amine either with thiophos-gene, calcium carbonate, chloroform, water [138, 139] or with carbon disulfide, N,N -dicyclohexylcarbodiimide, pyridine [140, 141],... 

Example 1 ot-AzidobenzylpenicWin via the Mixed Anhydride — A solution of o-azido-phenylacetic acid (8.9 grams, 0.05 mol) of triethylamine (5.1 grams, 0.05 mol) in 50 ml of dry dimethylformamide was stirred and chilled below -5°C. At this temperature ethyl chloroformate (4.7 ml) was added in portions so that the temperature was never above -5°C. After the mixture had been stirred for 20 minutes, dry acetone (100 ml), chilled to -5°C, was added in one portion, immediately followed by an ice-cold solution of 6-aminopenicillanic acid (10.8 grams, 0.05 mol) and triethylamine (5.1 grams, 0.05 mol) in 100 ml of water, and the stirring was continued for VA hours at 0°C. 

C. (Alternative) To 0.1M ethyl-chloroformate in 100 ml CHCI3 at -30° add a cold solution of 0.1 M (II) and 0.1 M triethylamine in 100 ml CHCI3 over forty minutes. Stir 1 /z hours at -20° to 5° and bubble NH3 through the cold mixture for twenty minutes. Stir one-half hour at room temperature, filter and extract the solid with CHClj. Combine CHCI3 extracts and filtrate and wash two times with cold NaOH solution and two times with water. Dry and evaporate in vacuum to get (III). 

An oxo derivative of the same ring system has also been synthesized <1998JRM2126> treatment of the dithiocarbamate derivative 119 with ethyl chloroformate in the presence of triethylamine resulted in the formation of the ring-closed product 120. 

The A"-ethoxycarbonyl derivative (192) was obtained from 191 with ethyl chloroformate and butyllithium, although p Tidine, triethylamine. 

To increase the yields of the ring closure reactions, a new method was developed that was successfully applied for the synthesis of alicyclic fused systems of both the parent oxazolidine-2-thione and tetrahydro-1,3-oxazine-2-thione (85S1149). As an example, the synthesis of 2-thioxoperhydro-l,3-benzoxazine 103 is described. The dithiocarbamate 101, prepared from the amino alcohol 100, carbon disulfide and triethylamine, was treated with ethyl chloroformate in the presence of triethylamine, to give the thioxo derivative 103 via the transition state 102 (85S1149). In this way, the fused-skeleton thioxooxazines (91, X = S, 92) can be prepared with considerably higher yields (50-70%) than by the earlier methods (85S1149). 

On the other hand, Wyeth-Ayerst chemists ° encountered limitations with this methodology during their syntheses of spirocyclic 2,4-oxazolidinediones derived from isoindole (Scheme 6.55). For example, reaction of 246 with chlorosulfonyl isocyanate followed by cyclization with potassium terf-butoxide afforded poor to modest yields of 247 when R was a substituted benzyl group. Cyclization of 246 using ethyl chloroformate (ECF), triethylamine and 4-(dimethylamino)pyridine (DMAP) in refluxing tetrahydrofuran (THF) gave 247 in only 29% yield when R was methyl and failed completely if R was an isopropyl group. However,... 

The carboxyl group of 4-oxo-4//-pyrimido[2,l-a]isoquinoline-3-carboxylic acids was esterified with various alcohols [84JAP(K)84/172490] and was converted into N-substituted 3-carboxamides by treatment with ethyl chloroformate in the presence of triethylamine in methylene chloride, followed by amines and hydroxylamine at 0°C [84JAP(K)84/172490 85EUP143001]. 

A suspension of 4 g of trans-2-(2,5-dimethoxy-4-methylphenyl)-cyclopropanecarboxylic acid in an equal volume of H20, was treated with sufficient acetone to effect complete solution. This was cooled to 0 °C and there was added, first, 2.0 g triethylamine in 35 mL acetone, followed by the slow addition of 2.5 g ethyl chloroformate in 10 mL acetone. This was stirred for 0.5 h, and then there was added a solution of 1.7 g NaN i in 6 mL If20, dropwise. After 1 h stirring at 0 °C, the mixture was quenched by pouring into H20 at 0 °C. The separated oil was extracted with EtzO, and extracts dried with anhydrous MgS04. Removal of the solvent under vacuum gave a residue of the azide, which was dissolved in 10 mL anhydrous toluene. This solution was heated on the steam bath until the nitrogen evolution was complete, and the removal of the solvent under vacuum gave a residue of crude isocyanate as an amber oil. This intermediate isocyanate was... 

The triethylamine salt of 2,2-dimethyl-3-(3,4-methylenedioxyphenyl)-propionic acid (5.4 g amine, 11.4 g acid) was dissolved in 10 mL 11,0 and diluted with sufficient acetone to maintain a clear solution at ice-bath temperature. A solution of 6.4 g ethyl chloroformate in 40 mL acetone was added to the 0 °C solution over the course of 30 min, followed by the addition of a solution of 4.1 g sodium azide in 30 mL H20. Stirring was continued for 45 min while the reaction returned to room temperature. The aqueous phase was extracted with 100 mL toluene which was washed once with H20 and then dried with anhy drou s Mg S04. Thi s org ani c sol uti on of the azide was heated on a steam bath until nitrogen evolution had ceased, which required about 30 min. The solvent was removed under vacuum and the residue was dissolved in 30 mL benzyl alcohol. This solution was heated on the steam bath overnight. Removal of the excess benzyl alcohol under vacuum left a residue 13.5 g of l-(N-(benzyloxycarbonyl)amino)-1,1 -dimethyl-2-(3,4-methylenedioxyphenyl)ethane as an amber oil. The dimethyl group showed, in the NMR, a sharp singlet at 1.30 ppm in CDCH,. Anal. (C19H2lN04) C,H. This carbamate was reduced to the primary amine (below) or to the methylamine (see under MDMP). 

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