Von Braun

In 1902, von Braun (76) showed that ammonium N-phenyldithio-carbamate condensed at low temperature to give ethyl N-phenyldithio-carbamylacetate (52) which, on heating, led to N-phenylrhodanine (53). 

Treatment of quinoline with cyanogen bromide, the von Braun reaction (17), in methanol with sodium bicarbonate produces a high yield of l-cyano-2-methoxy-l,2-dihydroquinoline [880-95-5] (5) (18). Compound (5) is quantitatively converted to 3-bromoquinoline [5332-24-1], through the intermediate (6) [66438-70-8]. These conversions are accompHshed by sequential treatment with bromine in methanol, sodium carbonate, or concentrated hydrochloric acid in methanol. Similar conditions provide high yields of 3-bromomethylquinoHnes. 

H. A. Hageman, "The Von Braun Cyanogen Bromide Reaction," in R. Adams and co-workers, eds.. Organic Reactions, Vol. 7, John Wiley Sons,... 

Deall lation. Chloroformates such as vinyl chloroformates (40) are used to dealkylate tertiary amines. Chloroformates are superior to the typical Von Braun reagent, cyanogen bromide, because of increased selectivity producing cleaner products. Other chloroformates such as aHyl, methyl, phenyl, and trichloroethyl have also been used in dealkylation reactions. Although the dealkylation reaction using chloroformates is mostiy carried out on tertiary amines, dealkylation of oxygen or sulfur centers, ie, ethers or thioethers, can also be achieved. a-Chloroethyl chloroformate [50893-53-3] (ACE-Cl) (41,42) is superior to all previously used chloroformates for the dealkylation reaction. ACE-Cl has the advantage that the conditions requked for ACE... 

Pargyline hydrochloride (Eutonyl, (V-methyl-n-propargylbenzylamine hydrochloride) [306-07-0] M 195.7, m 154-155 , 155 , pK 6.9. Recrystd from EtOH-Et20 and dried in vacuo. It is very soluble in H2O, in which it is unstable. The free base has b 101-103°/ 1mm. It is a glucuronyl transferase inducer and a monoamine oxidase inhibitor, [von Braun et al. Justus Liebigs Ann Chem 445 205 1928, Yeh and Mitchell Experientia 28 298 1972 Langslrom et al. Science 225 1480 1984.]... 

Similarly, von Braun and Schmitz found that A-benzoylconiine, on distillation with phosphorus pentachloride, underwent ring scission with elimination of the nitrogen atom and formation of the dichlorooctane, CH2CI. (CH2)3. CHCl. CHa. CH. CH3. 

Nicotine (von Braun) Tobacco (ghranetaln) D. Eopaoodll (SpSth et al.)... 

Whilst tropyltropine (atropine) is mydriatic, this property is of a low order in benz yltropine and is absent in benzoyl- -tropine. The former is a weak and the latter a potent local anaesthetic. This parallelism in the influence of the tropyl and benzoyl radicals in developing mydriatic and local aniesthetic action respectively, has been shown by von Braun and his co-workers to occur through an extensive series of hydroxyalkylamines in addition to tropine. Considerable modification may be made in the structure of tropine without impairing its capacity for yielding mydriatics anaesthetics. Thus von Braun, Muller and Rath found that e tropyl- and benzoyl-esters respectively of liomotropine (I) and of N-hydroxyalkylnortropanes (III) are comparable with atropine and tropacocaine (derived from tropine (II) and 4-tropine (II) ), respectively... 

Benzyl groups, as well as other alkyl groups, can be converted to various carbamates as a variation of the von Braun reaction.The carbamates can then be cleaved by conditions that are outlined in the section on carbamates. 

A common method for the preparation of alkyl cyanide 2 is the treatment of corresponding alkyl halides 1 with cyanide. The corresponding reaction with aromatic substrates is called the Rosenmund-von-Braun reaction. 

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