ethyl chloroformate

Ethoxycarbonylamino acids are advantageously prepared in the same manner using ethyl chloroformate or diethyl dicarbonate.

Ethyl chloroformate is the ethyl ester of chloroformic acid.

The reaction of tropinone enolate with ethyl chloroformate led, via a ring opening, to the cycloheptenone derivative 9.

The reactivity of some carbocyclic lactams and some γ-thiolactams with ethyl chloroformate has been studied.

The ring nitrogen is then protected as its ethyl carbamate by acylation with ethyl chloroformate (6).

Reaction of (3) with ethyl chloroformate results in N-demethylation and consequent formation of the corresponding carbamate.

Formation of the ethyl urethane is then made possible by reacting Linsidomine with Ethyl chloroformate.

A similar, more recent synthesis pathway involves producing 2-tropinone from cocaine and treating the product with ethyl chloroformate producing a bicyclic ketone.

An azidopenicillin sodium salt (1) is reacted with mixed carbonate ester 2 (itself prepared from acetaldehyde and ethyl chloroformate) to give ester 3.

More recently, it has become much more commonplace to use ethyl chloroformate instead of cyanogen bromide for the Von Braun degradation demethylation step.

Important chloroformate esters include 4-nitrophenyl chloroformate, fluorenylmethyloxycarbonylchloride, benzyl chloroformate and ethyl chloroformate.

Von Braun reaction with BrCN (or ethyl chloroformate) followed by saponification of the intermediate leads to the 2 amine (6).

This compound may be prepared from 1,3-propanediol and ethyl chloroformate (a phosgene substitute), or from oxetane and carbon dioxide with an appropriate catalyst:

Protection with ethyl chloroformate followed by reaction with thionyl chloride SOCl and then tetrahydrofuran yields 4-carboethoxysyringic acid 4-chloro-1-butyl ester.

A modern variation of the Von Braun rxn has been developed where BrCN has been superseded by ethyl chloroformate, respectively.

Ethyl carbamate is a white crystalline substance produced by the action of ammonia on ethyl chloroformate or by heating urea nitrate and ethyl alcohol:

The amino group is protected by rxn with ethyl chloroformate, the ester group is saponified, and then cyclodehydration with polyphosphoric acid leads to the dihydroquinoline ring system (2).

Treatment of hydrazino derivative 13 with acetylacetone, triethylorthoformate, carbon disulphide, ethyl chloroformate, and acetic anhydride afforded triazolopyrimidothienopyridocinnolines 14-16, 18, and 21, while with nitrous acid the corresponding tetrazolo compound 19 was produced.

A two-step synthesis starts from hydrazine, first by alkylation with ethyl chloroformate, followed by treating the resulting diethyl hydrazodicarboxylate with chlorine (bubbling through the solution), hypochlorous acid, concentrated nitric acid or red fuming nitric acid.