Aminolysis ring opening with amines

The mechanism of the aminolysis and the electronic effects of substituents at C-2 or C-4 on the kinetics of amide bond formation have been studied. In some cases, ring opening with amines occurs with partial isomerization of the exocyclic double bond. However, with more hindered compounds, such as unsaturated oxazolones derived from ketones, ring opening is stereospecific.Ring opening using diamines has also been described. Selected examples of dehydroamino acid amides prepared by aminolysis of unsaturated 5(4//)-oxazolones are shown in Table 7.40 (Fig. 7.51). 

Ti(OPr1)4-mediated nucleophilic ring opening of 2,3-epoxy-alcohol with primary amine requires more rigorous conditions, and the product is a complex mixture. Lin and Zeng22 found that this problem could be overcome and moderate to good yields could be obtained under weak base conditions by in situ /V-acylation of the aminolysis product with benzoyl chloride. 

The data in Table II.ll show that the participation of the Sn(ANRORC) mechanism decreases with decreasing potassium amide/substrate ratio. When no potassium amide is present, the participation of the ANRORC mechanism is zero and the aminolysis occurs according to the Sn(AE) mechanism. Apparently in the amination of the highly 77-electron-deficient 1,3,5-triazines, a competition is involved between the strong nucleophilic amide ion, which leads via a-adduct 136 and the ring-opened compound 137 to product 2-[ N-amino]-4,6-diphenyl-l,3,5-triazine, and the weaker nucleophile liquid ammonia, which replaces by an Sn(AE) process the... 

Aminolysis of mei o-epoxides is facilitated by Sc(OTf)3. In the presence of bipyridyldiol 8 chiral products are obtained/ mei o-A-Acylaziridines react with Me3SiN3 to provide (3-azido amines, and a chiral Bronsted acid (e.g., 9) renders the ring opening asymmetrical/ ... 

Aminolysis of alkoxycarbene complexes with primary or secondary amines may generate /Z-mixtures of aminolysis products the configuration of which may be controlled within certain limits by the reaction conditions. For example, the reaction of tris(2-aminoethyl)amine with chromium methoxy(phenyl)carbene 130 carried out at -30 °C in ethereal solution gives a 91% yield of a Id-mixture of the E/E/E- and the / /Z-isomers oftripodal trischromium aminocarbene 131, whereas at ambient temperature the pure / /Z-isomer is formed in 74%. The ring-opening aminolysis of chromium oxacyclopentylidene 73 carried out at -78 °C in a 1 d -mixture of DMF and CHjClj affords a nearly quantitative yield of the tripodal E/E/E-amino(hydroxypropyl)carbene complex 132 (Scheme 11.31) [56]. 

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