La migration de groupes carboxamides lors de la transposition benzilique d'amides α,β‐dicarbonylés. 24e Communication sur les réductones et les composés tricarbonylés‐1,2,3 [1]

Abstract

Under the conditions of the benzilic acid rearrangement, α,β‐diketobutyryl‐di‐phenylamide (Ia) and ‐N‐methylanilide (Ib) are transformed into tartronic acid derivatives (VI), which decarboxylate to lactamides VII. It is proved by 14‐labelling of Ia, that the reaction takes place by carbonamide group migration. The reaction was followed kinetically by polarography at a fixed potential; at low pH the velocity is proportional to [OH⊖], at higher pH it becomes independent of [OH⊖], which is explained by complete transformation of I into its hydrate‐anion. The equilibrium between I and its hydrate was measured by UV.‐spectroscopy.

Nucleophilic 1,2‐Shifts of Carboxamide Groups in the Benzil‐Benzilic Acid Type Rearrangement of 4‐Aryl‐2,3‐dioxobutyramides and of Quinisatine

“…If the benzyl group had migrated in the rearrangement, the tracer would have been found in the carboxyl group of 2a* and hence in the released CO,. Thus, the result supports the migration of the CONH, group as observed before in the similar rearrangement reactions [6] [714).…”

“…Kinetics. -In preceding kinetic investigations on rearrangements involving carboxamide-group migrations in the benzil-benzilic acid rearrangement we had found that for N,N-diphenyl-a$-dioxobutyramide [6] the rate of rearrangement is proportional to [OH-], but tends towards a plateau at high pH values; for quinisatine (6) no clear order of dependence of the rearrangement rate upon [OH-] had been found [7]. We have now measured the rate of rearrangement of l a -c at different alkali concentrations; on the same occasion, we have extended the range of our former measurements with 6, for which the course of the rearrangement had been established earlier [7].…”

“…Rutes oj'AIkuline Rearrangement of la, Ib, and Ic (polarography in EtOH/H,O 1:l at fixed potential of -1.3 V; p = 0.1; 25.0" i 0.05"; each value represents the mean of 3 to 4 (for l a and Ib) and cu. 2 (lc) measurements) ") Ionic strength 0.6. h, Variable ionic strength Meusurements: 1: In a polarographic apparatus as described [6] [7] (Polarecord Metrohm, equipped for acceleration of droplet formation), 0.5 ml of soln. d were injected into a mixture of 10.0 ml of soln.…”

“…For instance ester groups ROOC have been demonstrated to migrate in Wagner-Meerwein [3], pinacol [4] and benzil-benzilic acid rearrangements [ 5 ] . We have found two cases of migration of carboxamide groups in the benzil-benzilic acid rearrangement of an open-chain compound, Me-CO-CO-CONPh, [6], and of a cyclic amide, quinisatine (6) [7]. On the other hand, Kwart and coworkers [XI have shown that there is no shift of the carboxamide group in the alkali-catalyzed rearrangement of alloxane and its N-substituted derivatives but exclusively cleavage of the C-N bond and migration of the N-group; Smith and Kan [9] found the same result for the rearrangement of phthalonimide.…”