PHOSPHORYL TO CARBONYL MIGRATION OF AMINO GROUPS IN MIXED ANHYDRIDES. THE EFFECT OF N-SUBSTITUENTS
The rates of fragmentation of mixed anhydrides (MeO)(p-X-C6H4NMe)P(O)OC(O)Ph (1) (X=MeO, H, Cl, CF3) giving carboxyamides PhC(O)NMe(C6H4-X-p) were measured in CDCl3 at 70 deg C.The reaction constant ρ=+0.85 was obtained.The magnitude of ρ is taken as an indication of low sensitivity of rate to polar effects of substituents (in agreement with the concerted mechanism postulated), and its positive sign suggests that the cleavage of the P-N bond is more advanced in the transition state than is the formation of the N-C bond.
Symes, Jillian,Modro, Tomasz A.
p. 113 - 118
(2007/10/02)
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