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1.2- Elimination reactions, characteristics scope

In a detailed study, the scope and limitations of the Diels-Alder reaction of amidines and related compounds with 1,3,5-triazines arc discussed.10 The reactions with the amidine hydrochlorides 15 (X = NH2) are best conducted at temperatures of 90-100 °C and in polar aprotic solvents (particularly in dimethylformamide). As expected for inverse electron demand Diels-Alder reactions, the reaction exhibits characteristic 1,3,5-triazine substituent effects (C02Et >HI> SMe). Thioimidates, e.g. 15 (X — SMe), undergo a similar reaction with 1,3,5-tri-azines with varying yields and competing amine or thiol elimination while imidates, e.g. 15 (X = OMe) are unreactive under the examined reaction conditions.10... [Pg.796]

The a,p-double bond in amino acid derivatives and peptides represents, in addition to the amino and carboxy groups, the introduction of a third highly reactive function into the molecule. It is therefore pertinent in a discussion of the a,P-dehydroamino acids to devote some attention to their primary addition products, such as derivatives of a-mercapto- and a-hydroxy-a-amino acids. Further topics relevant in this context are their relationship to P-hydroxy- and P-mercapto-a-amino acid derivatives (elimination-addition sequence), as well as syntheses and reactions of pyruvoylamino acids, which result from the hydrolysis of dehydropeptides and can possibly serve as precursors of the latter by condensation with amino acid amides. On the other hand, p,y- and y S-dehydroamino acids will be excluded from the scope of this discussion. The isolated double bonds of these compounds undergo the normal olefin reactions and display no unusual characteristics. [Pg.253]


See other pages where 1.2- Elimination reactions, characteristics scope is mentioned: [Pg.221]    [Pg.187]    [Pg.131]    [Pg.131]    [Pg.344]    [Pg.345]    [Pg.1819]    [Pg.258]    [Pg.121]   
See also in sourсe #XX -- [ Pg.248 , Pg.249 , Pg.250 ]




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