The reaction of RuHCl(PPh3)3 with the tetradentate ligand [PPh2((ortho-C6H4)CH2NHCH2 - )]2 {ethP2(NH)2} in THF produces the new complex trans-RuHCl{ethP2(NH)2} (1) as a mixture of two isomers. The complex RuHCl{ethP2(NH)2} (1) when activated with KOtBu/KH is a very active catalyst for the hydrogenation of benzonitrile to benzylamine in toluene, more active than the known catalyst Ru(H2)2H2(PCy3)2 (2). A mixture of 1 and 2 and base also results in efficient conversion of benzonitrile to benzylamine. The complex RuHCl{tmeP2(NH)2} (3) where tmeP2(NH)2 is [PPh2((ortho-C6H4)CH2NHCMe2 - )]2 is a less active catalyst for this reaction. These catalyst systems are air sensitive and extremely moisture sensitive. Experimental and theoretical (DFT) evidence is presented for a new mechanism for nitrile hydrogenation:  the successive hydrogenation of the CN triple bond and then the CN double bond of the intermediate imine by H+/H- transfer from a trans dihydride active catalyst. The amido complex RuH{tmeP2N(NH)} (4) has similar activity to 3/base for the base-free hydrogenation of benzonitrile and is moderately active for the catalytic hydration of benzonitrile. The new complex RuH(BH4){ethP2(NH)2} (7) was prepared by reacting 1 with NaBH4 but is found to be a poor catalyst for nitrile hydration.

The reaction of alpha,beta-unsaturated carbonyl compounds with aminoacetonitrile hydrochloride furnishes 3,5-disubstituted 3,4-dihydro-2H-pyrrole-2-carbonitriles in a one-pot reaction sequence. While these products can serve as starting materials for the preparation of polysubstituted pyrrolizidines, they are kinetically stable against the base-induced elimination of HCN. In contrast, their 2-substituted analogues obtained from alpha-substituted alpha-aminonitriles can be readily converted to the corresponding 2,3,5-trisubstituted pyrroles under microwave irradiation. The key step presumably involves the thermal electrocyclization of a stabilized 2-azapentadienyl anion formed by condensation of the reactants and subsequent deprotonation.

2,3,4,5-Tetrasubstituted pyrroles have been prepared with high regioselectivity by a formal cycloaddition of alpha-(alkylideneamino)nitriles and nitroolefins followed by elimination of HCN and HNO2. The reaction allows the convergent construction of the pyrrole ring in four steps from a nitroalkane and three aldehydes.

Synthesis of g-Amino Acid Esters by 1,4-Addition of Deprotonated a-Aminonitriles and a-(Alkylideneamino)nitriles to a,b-Unsaturated Esters g -A m i n o A c i d E s t e r s f r o m a -A m i n o n i t r i l e sAbstract: a-Aminonitriles and a-(alkylideneamino)nitriles can serve as readily available a-aminocarbanion equivalents. Their conjugate addition to a,b-unsaturated esters followed by reduction furnishes polysubstituted g-amino acid esters in moderate to high yield.

Cyclocondensation of α-Aminonitriles and Enones: A Short Access to 3,4-Dihydro-2H-pyrrole 2-Carbonitriles and 2,3,5-Trisubstituted Pyrroles. -Treatment of enones with aminoacetonitrile and aminonitriles derived from aromatic aldehydes provides a facile approach to dihydropyrroles like (III), (IV), and (XII). The latter can smoothly be transformed into trisubstituted pyrroles and pyrrolizidines. The reaction of α-aminonitriles generated form aliphatic aldehydes leads to imines of type (IX). Their treatment with KOtBu also provides trisubstituted pyrroles. -(BERGNER, I.; WIEBE, C.; MEYER, N.; OPATZ*, T.; J.