Ethyl chloroformate reaction

The cyclobutanone (255) reacted with acid to furnish the keto-acid (259). Upon esterification, ketalization and reduction, (259) was converted to the alcohol (260). Mesylation of the alcohol (260) and then treatment of the mesylate with NaN3 in DMSO provided the azide (261). The azide (261) was then transformed to the urethane (262) by reduction and ethyl chloroformate reaction. The urethane (262) was deketalized by acid, nitrosated by N204—NaOAc and decomposed by NaOEt—EtOH to give the ketone (263) 89). The ketone (263) served as a starting material for the synthesis of veatchine (264)90). 

SBSE can be successfully used in the analysis of environmental samples [93-97] and for food analysis [98, 99]. PDMS is the most commonly used polymer, primarily because of its thermal stability and durability. SBSE has been modified by application of derivatization with different reagents (acetic anhydride, BSTFA, etc) [100-104]. This approach is suitable for the extraction of compounds requiring derivatization. The use of multistep derivatization with several extraction elements (each reaction is performed on a different stir bar) allows efficient extraction, desorption, and chromatographic analysis of compounds with different functional groups (e.g., phenols, steroids, amines, thiazoles, ketones). Acetic anhydride (ester formation), ethyl chloroformate (reaction of acids and amines), tetraethyloborane, and sodium bis-trimethylotrifluoroacetamide have been used for extraction and simultaneous derivatization [105]. 

When lithium aluminum hydride was applied, besides reduction of the C-4—N-5 double bond, the ester group was converted to a hydroxymethyl group. S By reaction with dry formic acid under reflux conditions, the pyrroloquinazoline-2-carboxylates 63 yielded the 6-formyl-5,6-dihydro derivatives 65. S The formyl group was transformed into a methyl group by diborane. S The NH group of the dihydro derivatives 64 was acylated by ethyl chloroformate. Reaction with ethyl acrylate and acrylonitrile involved a Michael addition.The ethoxycarbonyl moiety in position 2 and on the side chain in position 6 was hydrolyzed to a carboxylic group by the action of potassium hydroxide in aqueous methanol and was reduced to a hydroxymethyl group by lithium aluminum hydride in ether. 

The ester 870 is prepared by the cross-coupling of the chloroformate 869 with an organotin reagent. Some chloroformates are easily decomposed by a Pd catalyst, and hence the reaction should be carried out by slow addition of the chloroformates. Similarly, the amide 872 is prepared by the reaction of the carbamoyl chloride 871 [742]. The coupling of alkylcopper with ethyl chloroformate catalyzed by Pd affords esters[743]. 

Phenyl-3-oxopropanoic acid (25 mmol) and EtjN (87.5 mmol) were dissolved in THF (150 ml) and cooled to —40°C. Ethyl chloroformate (27.5 mmol) was added dropwise to this solution and then the reaction mixture was stirred for 30 min at —20°C. Di-n-hexylamine (27.5 mmol) was added to the suspension and it was stirred at room temperature for an additional hour. The reaction mixture was diluted with water (100 ml) and extracted with ether (400 ml). The extract was washed with aq. 5% HCl (100 ml) and brine (2 X 100 ml) and dried over NajSO. The crude amide was obtained by removal of the solvent in vacuo and phenylhydrazine (25 mmol) was added. The mixture was heated to 100°C for 30 min. The residue was held in vacuo to remove the water formed and then powdered ZnCl2 (125 mmol) was added. The mixture was heated at 170"C with manual stirring for 5 min. The cooled residue was dissolved in acetone (100 ml) and diluted with ether (500 ml). Water (100 ml) was added. The organic layer was separated and washed successively with 5% aq. HCl (100 ml) and brine (2 x 100 ml) and dried over NajSO. The solvent was removed in vacuo, and the residue was recrystallized from EtOAc-hexane. The yield was 79%. 

The reaction between ethyl chloroformate and 2-aminothiazoles provides easy synthetic access to thiazolyl 2-carbamaies (269) (Scheme 163)... 

Ethyl chloroformate is used in the manufacture of ore flotation agents by reaction with various xanthates (48). 

The ethoxycarbonyl group was developed for the protection of phosphonates. The derivative is prepared by reaction of tris(trimethylsilyl) phosphite with ethyl chloroformate and can be cleaved by hydrolysis of the ester followed by silyla-tion with bistrimethylsilylacetamide. ... 

The carbamates, derived from the reaction of 8-aminoquinoline with phenyl or ethyl chloroformate, upon reduction with NaBH4 gave the... 

Reaction of the glycol (17) from hydroxylation of styrene with ethyl chloroformate affords the carbonate ester, 18. Treatment of this last with ammonia at elevated temperature gives the sedative, styramate (19)A similar sequence on the ethyl ana-... 

Hydrazine 835 underwent ring closure with one carbon cyclizing reagents to afford 837 and/or /V-acyl derivatives 836. The N-acyl derivatives underwent cyclization on treatment with phosphorus oxychloride. They were also prepared by the reaction of hydrazones 838 with thionyl chloride (84JHC1565). Compound 835 underwent ring closure with carbon disulfide and ethyl chloroformate to give 839 (Scheme 169). 

Treatment of sulfmylaziridine 73 (Scheme 3.23) with MeMgBr and then with tert-butyllithium gave aziridinyllithium 74, which reacted with ethyl chloroformate to afford aziridine-2-carboxylate 75 in 64% yield [70]. The reaction was stereospecific, giving 75 as a single diastereomer. 

Ethyl chloroformate obtained from Aldrich Chemical Company, Inc., was distilled, b.p. 93°. The progress of the reaction may be followed by proton magnetic resonance spectroscopy. Aliquots are partitioned between dichloromethane and water, the organic layer is concentrated, and the spectrum is recorded. A quartet from the ethoxy group of the mixed anhydride appears at 8 4.2. Ethyl chloroformate, which exhibits a quartet at 6 4.3, is removed in the concentration step. 

As indicated by the mechanism, carboalumination is a syn addition. The resulting vinylalanes react with electrophiles with net retention of configuration. The electrophiles that have been used successfully include iodine, epoxides, formaldehyde, and ethyl chloroformate.229 We will also see in Chapter 8 that the vinylalanes can undergo exchange reactions with transition metals, opening routes for formation of carbon-carbon bonds. 

The acyl azide intermediates are prepared either by reaction of sodium azide with a reactive acylating agent or by diazotization of an acyl hydrazide. An especially convenient version of the former process is treatment of the carboxylic acid with ethyl chloroformate to form a mixed anhydride, which then reacts with azide ion.265... 

In this series, too, replacement of the N-methyl by a group such as cyclopropylmethyl leads to a compound with reduced abuse potential by virtue of mixed agonist-antagonist action. To accomplish this, reduction of 24 followed by reaction with tertiary butylmagnesium chloride gives the tertiary carbinol 27. The N-methyl group is then removed by the classic von Braun procedure. Thus, reaction with cyanogen bromide leads to the N-cyano derivative (28) hydrolysis affords the secondary amine 29. (One of the more efficient demethylation procedures, such as reaction with ethyl chloroformate would presumably be used today.) Acylation with cyclopropylcarbonyl chloride then leads to the amide 30. Reduction with lithium aluminum hydride (31) followed by demethylation of the phenolic ether affords buprenorphine (32).9... 

Reaction of salicylamide 185 (obtainable from a suitable activated derivative of salicylic acid and N,N-diethylethylenediamine) with ethyl chloroformate... 

Ring D inversion seems to be a crucial step in biogenetic transformations of protoberberines to related alkaloids such as rhoeadine, retroprotoberberine, spirobenzylisoquinoline, and indenobenzazepine alkaloids. 8,14-Cyclober-bin-13-ol 478 derived from berberine (15) was successively treated with ethyl chloroformate, silver nitrate, and pyridinium dichromate (PDC) in dimethyl-formamide to give the keto oxazolidinone 479 (Scheme 98). Heating of 479 with 10% aqueous sodium hydroxide in ethanol effected hydrolysis, retro-aldol reaction, cyclization, and dehydration to provide successfully the... 

The tetracyclic /3-carboline derivatives 452-454 have been prepared as sleep disorder therapeutics. The synthesis (Scheme 100) involves the reaction between the enamino ester 451 and acrylic acid derivatives, activated in certain cases with ethyl chloroformate <1997TL8475>. 

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