Amino effect

Ring-closure reactions that involve a /-amino group on a 1,2-diazine skeleton and a vinyl moiety in its t /// t -position occur via the so-called /-amino effect. Although this reaction does not involve reaction at the nitrogen atom itself, it is a very specific reaction that can only occur on /-amines and is therefore incorporated in this section. The reaction 

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Protein Size (kDa) Type Function Mutation/amino Effect on... 

The reaction of 1,2-diazinamines with electrophiles is well studied while the substitution of amines-imines by nucleophiles is a highly nonstandard process. Nevertheless, even in the latter class new examples appeared since CHEC-II(1996) <1996CHEC-II(6)1>. A new section dealing with the so-called f-amino effect was added since many examples on 1,2-diazines have appeared since the mid-1990s. 

Section 8.11.6.2.1) <2007ARK(viii)7>, and to the /ftt-amino effect <2006RCB384>. The intramolecular photocycloaddition of novel sulfur-substituted l,3-dioxin-4-ones (Equation 98) has been described <2006JA9040>. 

Heterocycles by Ring Closure of Ortho-substituted t-Anilines (the t-Amino Effect) O. 

Amino acids as synthons for heterocyclic compounds, 64, 1 f-Amino effect, 14, 211, 65, 1 A-Aminoazoles, 53, 85... 

An ingenious method for the construction of the pyridine ring based on the tert-amino effect was used (1990RTC481) in the synthesis of a series of [3,2-Z>]-annu-lated thienoazines. Prolonged refluxing of diene aminodinitriles 166 in butanol affords thieno[3,2-Z>]indolizines and thieno[2,3-e]quinolizines of general formula 167. 

Thermolysis of 3-(2,2-dicyanovinyl)-4-(l-piperidyl)pyridine (15, X = CH2) in DMSO produces the naphthyridine (16, X = CH2) by means of the "tert-amino effect" proposed by Meth-Cohn and Suschitzky <95SL622>. Where, however, X is a N, O or S an alternative cyclisation takes place, when the pyridoazepines (17) are formed. This new variant of the "rert-amino effect" is postulated to arise by the intermediate formation of (18). 

The first example of a surprising reaction sequence due to a /-amino effect was observed by Pinnow as early as 1895 during his attempts to prepare the acetyl derivative (3) of o-aminodimethyl-aniline (1) by prolonged reflux in acetic anhydride. He obtained 1,2-dimethylbenzimidazole (2) instead, and on the basis of analogous observations in related reactions he suggested that the formation of... 

It is the purpose of this review to collate all the available material relating to the (amino effect and to attempt a rationalization of its operative influence in a mechanistic manner. The cyclizations of ortho-sustituted (-anilines are described in two main sections. The first discusses ring closures between the ortho substituent and the (-nitrogen (4), while the second chapter deals with those ring formations which involve the a-methylene groups attached to the nitrogen (5). 

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