Imino reaction with amines

Thioamides (86) are more resistant to hydrolysis than the corresponding amides. By reaction with amines, hydroxylamine and hydrazine they tend to eliminate hydrogen sulfide to yield the imino derivatives (90)—(92) (Scheme 49). 

Tosyloxypyridine, from pyri-dine-l-oxide, 723 trans-2-Imino-l 2ff)-pyridine-acrylic acid, 71 Triacetic acid lactone, 655 reaction with, amines, 655 ammonia, 655 glycine, 655... 

Instead of formyl groups, imino groups formed immediately after the hydroformy-lation by the reaction with amines can also be attacked by C-nucleophiles. Such a combination of metal catalysis and organocatalysis was realized in a tandem reaction covering hydroformylation and Mannich reaction by the Eilbracht group (Scheme 5.146) [36]. The reaction rate and stereoselectivity were strongly dependent on the temperature. At room temperature, almost no conversion of the olefin... 

The xyluronosylamine 8 gave the ring expanded benzylamine adduct 9, that could be V-methylated to 10 or reduced to the 1,5-imino-alditol 11 as indicated in Scheme 1. The amidine based pseudo-disaccharide 12 has been synthesized and shown to be a competitive inhibitor of a-mannosidase (Kj = 2.6pM). Glucosyl-amidines such as 13 were obtained from the corresponding glucosylthioamides such as 14 on reaction with amines and mercury(II) oxide. 

Ytterbium triflate [Yb(OTf)3] combined with TMSG1 or TMSOTf are excellent reagents for the conversion of a-methyl styrene and tosyl-imines into homoallylic amides 32 (Equation (19)) (TMS = trimethylsilyl).29 These conditions produce the first examples of intermolecular imino-ene reactions with less reactive imines. Typically, glyoxalate imines are necessary. A comprehensive examination of the lanthanoid metal triflates was done and the activity was shown to directly correlate with the oxophilicity scale. The first report used preformed imines, and subsequently it was found that a three-component coupling reaction could be effected, bypassing the isolation of the intermediate imine.30 Particularly noteworthy was the successful participation of aliphatic aldehydes to yield homoallylic amines. 

Amines other than a-amino acids will also give a colour reaction with ninhydrin but without the production of carbon dioxide. Thus /3-, y-, 8- and e-amino acids and peptides react more slowly than a-amino acids, to give the blue complex, while imino acids result in the formation of a yellow-coloured product which can be measured at 440 nm. Removal of substances such as protein, ammonia and urea from biological samples may be necessary in quantitative work because they also react in a similar manner. 

Cyano-4-quinazolinones (4-oxo-3,4-dihydro-2-quinazolinecarbonitriles) 975 are available from 2-[A -(chloro-dithiazole)imino]benzoate esters 973 by reaction with primary aliphatic amines at room temperature <1998JHC659, 2002H(57)1471, 2002TL3993, 2005TL7477>. 

Reaction of hydroxyl groups with amine units with formation of imino groups ... 

Benzoxazin-4-ones (39) react with amines to give quinazolinones (40) (77JOC656), but this typical reaction is replaced in 1,3-benzoxazine-2-thiones (41) by the formation of imino derivatives (42) since now the oxygen ring atom is joined directly to the aryl nucleus (76MI22700). 

Resin-bound amines can be converted into imines [710,711] or enamines by reaction with carbonyl compounds (Entries 6 and 7, Table 3.39). Resin-bound enamines have also been prepared by Michael addition of resin-bound secondary amines to acceptor-substituted alkynes [712], by Hg(II)-catalyzed addition of resin-bound secondary amines to unactivated alkynes [713], by addition of C-nucleophiles to resin-bound imino ethers [714], and by chemical modification of other resin-bound enamines [712,713,715], Acceptor-substituted enamines ( push-pull alkenes) are not always susceptible to hydrolytic cleavage by TFA alone and might require aqueous acids to undergo hydrolysis [716]. 

Certain geminal difluoro groups arc easily aminolyzed yielding imines or enamines.3,20-24 An imine-enamine equilibrium is generally observed,13,25 - 28 which is dependent on the substrate and the amine used. Nevertheless, /i-imino carboxylic esters are predominantly obtained when a-hydrylperfluoro esters (e. g., 4) are reacted with primary amines, while reaction with secondary amines leads to the respective enamines.29,30... 

Another way to prepare 2-amino derivatives is by the reaction of 2-methylthio-4-oxo-4// derivatives with amines.268,288 The 2-methylthio-4-imino derivative reacted differently (see Section III,C,8). 2-Ainino-4-oxo-4//-pyrido[l,2-a]pyrimidine could have also been prepared by reducing the 2-hydrazino derivative with hydrogen sulfide.289... 

A very wide range of nucleophiles other than water and alcohols has been shown to react with co-ordinated nitriles (Fig. 4-15). The reaction with ammonia or amines is a particularly convenient method for the preparation of amidine complexes. Specific examples of these reactions are presented in Fig. 4-16, illustrating the formation of amide, imino-ether or amidine complexes. 

Alternatively, quaternisation of bisphosphinomethanes with bromine, followed by treatment with a primary amine and subsequent reaction with a base affords the corresponding methanes as a mixture of bis-imino and imino-amine tautomers the latter is favoured by /V-alkyl substituents, Scheme l.14 Irrespective of which valence tautomer is isolated, or whether a mixture is obtained, both afford the same methanide and methandiide following deprotonation so the Kirsanov method provides a valuable alternative to the preferred Phospha-Staudinger method when the required azide is unavailable or too unstable to be used. 

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