Reaction with BrCN

The technique is also used to introduce diene moieties, which enable the polymer for a highly efficient modification with dienophile components via Diels-Alder reaction [354], Therefore, methyl octa-4,6-dienoate is converted to octa-4,6-dienoic acid hydrazide, which is bound to dextran via reaction with BrCN. The maleimide-modified protein (albumin) is easily attached to the polymer backbone by Diels-Alder reaction (Fig. 50). 

Reaction of perhydropyrido[l, 2-n]pyrimidine with BrCN in the presence of MgO in a 1 1 mixture of CHCI3 and MeOH at 40 °C resulted in the formation of the ten-membered 6-methoxy-3,4,7,8, 9,10-hexahydro-l,5-diazecine-l,5-(2//,6//)-dicarbonitrile. Similar reaction of perhydropyrido[l, 2-n]pyrimidin-2-one led to the nine-membered 6-methoxy-4-oxo-2,3,4,5,6,7,8,9-octahydro-l//-l,5-diazonine-l-carbonitrile (99AJC1131). 

Salts of aliphatic or aromatic carboxylic acids can be converted to the corresponding nitriles by heating with BrCN or CICN. Despite appearances, this is not a substitution reaction. When R COO was used, the label appeared in the nitrile, not in the C02, and optical activity in R was retained. The acyl isocyanate... 

Scheme 10. Reaction of 1 with BrCN, Me3SiCN, and MeHal.

Kaupp et al. also exploited heterogeneous reactions with CICN and BrCN in the quantitative synthesis of cyanamides, cyanates, thiocyanates and derivatives [26]. Gaseous acids were shown to form salts with strong and weak solid nitrogen bases. Solid hydrohalides are formed quantitatively by reaction with vapours of HCl, HBr and HI the same applies to di-bases such as o-phenylen-diamines. The products are much more easily handled than when they are formed in solution. The solid products can in turn be used in reactions with gaseous acetone to form the corresponding dihydrohalides of 1,5-benzodi-azepines [27]. 

For the quantitative synthesis of thiocyanates by reaction with cyanogen chloride or cyanogen bromide it is essential to start with thiolates instead of thiols. The product salts are then removed by washing of the products with water. Thus, the various heterocyclic thiocyanates 224a-d are easily obtained in pure form by either gas-solid (CICN) or solid-solid (BrCN) reaction [92] (Scheme 29). 

The reaction of 2//-1,2,3-diazaphospholes with bromine involves a sequence of 1,2-addi-tion/elimination equilibria, R = Me, Ph (Scheme 22) <85CBi62l). 4-Bromo-1,2,3-diazaphospholes become accessible this way. Similarly, 4-phenylthio- and 4-methylthio-1,2,3-diazaphospholes result from reactions with sulfenyl halides <848591, 85CB1621). Iodine chloride reacts to give both the 4-chloro- and the 4-iododiazaphosphole <848591). Chlorination and bromination of diazaphospholes at C-4 has been achieved also with SO2CI2 and BrCN or NBS, respectively <848591). 

The ethyleneiodonium ion 158-1 has also been prepared by the direct iodination of ethylene using ICN-SbF5-S02ClF solution388 [Eq. (4.115)]. However, similar reaction with either BrCN or C1CN did not give the corresponding halonium ions 158-Br and 158-CI. 

The formation of the alkaline earth cyanide is the major pathway in the reaction M + BrCN. The other channel (giving MBr + CN) is observed for the reactions of Ba and Sr. The ratio of the cross section is o(BaCN)/ a(BaBr) 25-100 and a(SrCN)/o(SrBr) 250-1000 [363]. It was not possible to measure internal state distribution for the alkaline earth salts, but for the CN product of the minor channel, the vibrational distribution was found to be N(d = 1)/N(p = 0) <. 0.2 and Txot = 1250K for Ba + BrCN and TIot = 750 K for Sr + BrCN. The reaction dynamics appear to be consistent with an electron jump mechanism which would favour the breakup of the M+(BrCN) ion pair to give MCN + Br. 

Reaction of bicyclic lactam 273 with BrCN and MgO in MeOH/CHCl3 led to formation of the nine-membered amino compound 274 in 47% yield (Equation 37) <1999AJC1131>. 

Tertiary amines are cleaved with BrCN to give an alkyl bromide and a disubstituted cyanamide (Scheme 21). This process is called the von Braun reaction. Many examples have been reviewed. Tertiary amines with different R groups cleave so that the most reactive alkyl bromide is formed. Benzyl and allyl cleave better than alkyl, lower alkyl cleaves better than higher alkyl and aryl is not cleaved at... 

C(elemental carbon) reaction with Mg 10.2.3.5 CBrN BrCN... 

The conversion of gardnerine (1) to ochropine (39), a 2-acyl indole alkaloid isolated from the stem bark of Ochrosia poweri 175. was also carried out to establish structure 39 for the latter alkaloid. The reaction sequence is shown in Scheme 10. The nitrile function of 43 was converted to the carbomethoxy grouping by methanolysis. C-D ring cleavage with BrCN gave an epimeric mixture of C-3 hydroxyls which was then subjected to Cornforth oxidation to furnish 46. Decyanation of 46 and... 

Kaupp, G., Schmeyers, J., and Boy, J. 1998. Quantitative gas-solid reactions with CICN and BrCN synthesis of cyanamides, cyanates, thiocyanates, and their derivatives. European Journal of Chemistry, 4 2467-2474. 

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