Of azines with bifunctional nucleophiles

Charushin, V. N., Chupakhin, O. N., van der Plas, H. C., Reactions of Azines with Bifunctional Nucleophiles Cyclizations and Ring Transformations, 43, 301. 

Reactions of Azines with Bifunctional Nucleophiles Cyclizations and Ring Transformations... 

These examples seem to indicate that the interaction of azines with bifunctional nucleophiles can result in the formation of cyclization products only if we deal with an azine in which the reactivity of the leaving groups is enhanced by aza-activation or by the presence of electron acceptors. It has been found indeed that diazines, triazines, etc., are more inclined to cyclization than are pyridines. 

The meta-bridging cyclizations of azines with bifunctional nucleophiles usually occur in two steps and differ substantially in that respect from the 1,3-dipolar addition reactions performed on 3-hydroxypyridinium salts, which also result in meta-bridged adducts (Scheme 55) (76JCS(P1)2285). 

Refs.] REACTIONS OF AZINES WITH BIFUNCTIONAL NUCLEOPHILES 347... 

Reactions of azines with bifunctional nucleophiles can give rise to several cycloadducts, the structure depending on the nature of reagents, the structure of the azine substrate, and the reaction conditions. As discussed above, three types of cycloadducts are proposed to be formed in reactions of azines with such l,3-N,C-dinucleophiles as acetamidines and acetimino esters (Schemes 44, 54, 58, 69, and 71). 

The longest chapter of this volume, authored by Roger Gallo and Christian Roussel (France) and Ulf Berg (Sweden), gives a comprehensive account of the quantitative treatment of steric effects in heteroaromatic compounds—a subject that has been advanced significantly by these authors. Finally, V. N. Charushin and O. N. Chupakhin (USSR) and H. C. van der Plas (The Netherlands) review reactions of azines with bifunctional nucleophiles. 

Reissert compounds, 9, I 24, 187 Ring closure of ortlio-substituted t-anilines, heterocycles by, 14, 211 Ring-opening of flve-membered heteroaromatic anions, 41, 41 Ring synthesis of heteroaromatic nitro compounds, 25, 113 Ring transformations and cyclizations on reaction of azines with bifunctional nucleophiles, 43, 301 of five-membered heterocycles, 56, 49... 

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