Reaction with ethyl chloroformate

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... 

A tetracarboxylated derivative was prepared recently by reaction of a commercial reactive dye with two molar equivalents of aspartic acid. This novel derivative was evaluated by pad-dry-bake and pad-batch-bake methods under slightly acidic conditions in the presence of cyanamide as activator [49]. An interesting disperse dye containing a novel reactive anhydride system (7.54) was prepared from the parent dye carboxylate (7.53) by reaction with ethyl chloroformate in the presence of a tertiary base (Scheme 7.32). Such dyes will... 

The benzoic acid moiety common to many of the benzamides is prepared in straightforward manner from the methyl ether of p-aminosalicylic acid 141. Acylation on nitrogen (142) followed by chlorination gives intermediate 143 benzoic acid 144 is then obtained by removal of the acetyl group. Condensation of this acid with an aminopiperidine could be achieved by means of the mixed anhydride (prepared by reaction with ethyl chloroformate), which affords clebopride (145). Reaction with 3-aminoquinuclidine (146) of the intermediate prepared from acid 144 with carbonyldiimidazole affords zacopride (147) [36]. 

Finally, a third way of synthesis is from imipramine (7.1.1), which nndergoes demethylation by snccessive reaction with ethyl chloroformate, giving 5-[3-(Af-carbethoxy-iV-methyl)aniino-propyl]-10,ll-dihydro-5H-dibenz[b,f azepine (7.1.15), the alkaline hydrolysis of which leads to desipramine (7.1.13) [23,24],... 

Quenching this reaction with deuteriomethanol gave 2-methylcycloheptanone having deuterium at the 2-position (199 E = D) in 75% yield with 95% deuterium incorporation. Aldehydes and benzoyl chloride gave the desired products in 60-70% yields. Alkylation of the enolate intermediate (198) was successfully carried out with alkyl halides in the presence of HMPA in good yields. The reaction with ethyl chloroformate and chlorotri-ethylsilane gave enol carbonate (200) and sUyl enol ether (201) in 74 and 75% yield, respectively. 

Nitrophenyl chloroformate activation. The reaction of polysaccharides with chloroformates forming reactive carbonate derivatives has often been used to link bioactive compounds, such as affinity ligands and enzymes, onto polysaccharide matrixes. It was reported that upon reaction with ethyl chloroformate cyclic carbonate as well as ethyl-carbonate structures are formed (9-13). Activation with N-succinimi-do chloroformate (14), 2,4,5-trichloroformate (14) and 4-nitrophenyl chloroformate (14, 15) reportedly led to the introduction of pending carbonate moieties. 

Catalytic hydrogenation of 2-isobutyl-6-benzyl-5,6,7,8-tetrahydropyrido[4,3-J]pyrimidin-4-ol did not give the expected debenzylated derivative, but reaction with ethyl chloroformate gave the 6-carbethoxy derivative <86EGP241257, 88PHA475).. ... 

The reaction with ethyl chloroformate or CSC12 gave l,2,3,4-tetrahydropyrido[2,3-d]pyrimidine-2,4-dione <83JAP5802950, 84JAP5903479) and the corresponding 2-thione (267) <81JAP(K)81164189),... 

If the Reissert compound from the reaction with ethyl chloroformate (224) is lithiated at C-2 and subsequently treated with benzaldehyde, the final product is the l//-oxazolo[3,4-a]quinolin-l-one (225) (73JHC99). 

The leaves of Arnica montana L. contain a new alkaloid, N-ethoxycarbonyl-L-prolinamide (1). Its structure has been established by mass, i.r., and n.m.r. spectral analysis, and confirmed by synthesis from L-proline by conversion into the amide followed by reaction with ethyl chloroformate. The synthesis also settles the absolute configuration of the new alkaloid.3... 

Activate the C terminus of the growing peptide by reaction with ethyl chloroformate. 

Primary allylic amines. Aziridines can be converted into allyl carbamates by reaction with ethyl chloroformate to form N-ethoxycarbonylaziridines followed by thermolysis in benzene at 200-250°, Rearrangement of trisubstituted ethoxycarbonylaziridines is regiospecific. 

The ylid 371 prepared by treating cyclopropyltriphenylphosphonium bromide (with lithium diisopropylamide (LDA) produces a useful synthon on reaction with ethyl chloroformate . The fluoroborate salt (372) was shown to be an excellent reagent for cycloalkenylation of carbonyl compounds. The ylid was used successfully in the total synthesis of Spirovetivanes. ... 

Nitrodiphenyiamine is reductively cyclized with sodium borohydride in the presence of a base. A primary amino group and a carbon of ano er ring may be annulated by reaction with ethyl chloroformate to give the pyrazinone. 

An alternative route to aldehydes from carboxylic acids involves conversion of the acid into the carboxylic ethylcarbonic anhydride (1) by reaction with ethyl chloroformate. These anhydrides react with sodium tetracarbonylferrate... 

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