Phenanthroline-1-nitrile, hydration

In a similar way, transition metal ions catalyze the basic hydrolysis of esters of a-amino acids [271]. The rate law [272, 273] is analogous to that observed in the hydration of phenanthroline-nitrile, viz. 

Regioselective aza-annulation with acrylonitrile met with somewhat limited success. Aza-annulation of 10 with acrylonitrile resulted in the formation of a 75 25 mixture of 11 (eq. I).4 The mixture of 11 was taken on to 12, which was used in the synthesis of optically active 2,2 -bipyridines and 1,10-phenanthrolines. A more selective route to 11a was reported, and this approach started from optically pure (/ )-(+)-pu egone (13, eq. 2).5 In this case, regioselective Michael addition to give 14 was accomplished due to the presence of the isopropylidene moiety of the (/ )-(+)-pulegone. Subsequent rhodium catalyzed deisopropylidenation, nitrile hydration, and cyclization gave lib, which was taken on to (-)-pumiliotoxin C (15). 

Particularly well-studied examples of the hydration of nitriles are seen with the chelating ligands 2-cyano-1,10-phenanthroline (4.1) or 2-cyano-8-hydroxyquinoline (4.2). The products of the reactions are the appropriate amides, and the rate of hydration is enhanced by up to ten million times on co-ordination to nickel(n), copper(n) or cobalt(m). 

Nickel(II) compounds catalyze the hydration of organonitriles in basic and neutral media. For example, 2-cyano-l,10-phenanthroline is converted to the corresponding carboxamide by means of nucleophilic attack of OH on the nitrile carbon atom. The suggested mechanism is outlined in Scheme The same mechanism holds for the hydration reaction of... 

Breslow et al. 19) have investigated the mechanism of the divalent metal ion catalyzed hydration of 2-cyano-l,10-phenanthroline to the corresponding amide [see Eq. (7) below]. The cupric ion catalyzed reaction is extremely rapid lyz < 10 sec at 25°, pH 6—7). The Ni(II) and Zn(II) reactions, although slower, are greatly accelerated [the Ni(II) reaction by a factor of 10 ] in comparison to the rate of hydration observed in the absence of divalent metal ion catalysis. The reaction obeys a rate law which is second-order over all first-order with respect to hydroxide ion concentration, and first-order with respect to the 1 1 metal ion-substrate complex concentration. These authors suggest that the metal ion acts as a Lewis (general) add in activating the nitrile for external nucleophilic attack by hydroxide ion, as illustrated in Eq. (7) ... 

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