Évolution thermique et photochimique des triazolines résultant de l'addition des diazocomposés aux esters d'oximino-malonodinitriles, oximino-cyanoacétates et oximino-malonates de méthyle

Abstract

R e p le 23 avril 1994 JACQUES PERROCHEAU, ROBERT C& et JEAN-PIERRE FLEURY. Can. J. Chem. 72,2458Chem. 72, (1994. La thermolyse des 1,2,3-triazolines 4, 5, 6 permet l'obtention des aziridines correspondantes seulement lorsque X = Y = C0,Me et encore avec une faible rendement. Par contre la photolyse ou l'kvolution en prksence d'acide trifluoroacktique donne de bons rksultats B condition d'opkrer B une temptrature suffisamment basse. L'Ctude de la thermolyse de 4 6 montre un nouveau mode d'kvolution des 1,2,3-triazolines non encore signal6 dans la littkrature. La grande facilitk d'klimination du groupement paratoluknesulfonate ou benzoate est certainement le facteur dkterminant dans le comportement de ces composks.JACQUES F'ERROCHEAU, ROBERT C W , and JEAN-PIERRE FLEURY. Can. J. Chem. 72,2458Chem. 72, (1994.Thermolysis of 1,2,3-triazolines 4 , 5 , 6 leads to the corresponding aziridines only when X = Y = C02Me, and then with a very low yield. However, photolysis or evolution in the presence of trifluoroacetic acid gives good results when carried out at sufficiently low temperature. The thermolysis study of &6 shows a new route to 1,2,3-triazoline decomposition that has not yet been mentioned in the literature. The easy elimination of the paratoluenesulfonate or benzoate group explains this particular behaviour. Description des rCsultatsDans un travail antCrieur (I), nous avons montrC que les esters d'oximes 1, 2 et 3 rCagissent avec divers diazocomposCs pour conduire aux 1,2,3-triazolines 4-6 (Fig. 1). idines correspondantes sauf lorsque X = Y = C02Me, oh elles sont obtenues avec des rendements de 30-40%.Par contre, la photolyse en solution dans le dichloromCthane 2 -40°C conduit aux aziridines de f a~o n pratiquement quantitative. La photolyse de 4aA (X = CN, Y = CO,Me, R' = H) donne le mClange des deux aziridines diastCrCoisom&res 7aA' et 7aA" (proportions relatives 70130) (Fig. 2).Pour la triazoline 4aB (deux diastCrCoisom&res 4aB' et 4aB" dont les stCrCochimies ne sont pas attribukes) la formation des quatre aziridines diastCrCoisom&res 7aB est observte (Fig. 3). R ' R'Seule la photolyse des triazolines 4 (R = Ts) a CtC CtudiCe. La 7aB' A 7aB"" thermolyse de ces triazolines ne permet pas l'obtention des azir-

Investigation of benzoyloximes as benzoylating reagents: benzoyl-Oxyma as a selective benzoylating reagent

“…It has been found that Oxyma (6) can undergo side-reactions at the ethoxylcarbonyl group. 21,24 Therefore we also studied the tert-butyl ester 8 (derived from tert-butyl cyanoacetate) 25 and the bis-nitrile 9 (derived from malonitrile) 26 (Table 1). In order to complete the series we included the bis-ethoxycarbonyl derivative 10 (derived from diethyl malonate).…”

“…27 Several analogues of COMU have been reported to provide improved peptide couplings, most notably based on oximes 11 (derived from Meldrum's acid) 28 and 12 (derived from dimethylbarbituric acid), 29 which were also included in our studies. Oximes 6, 10-12 or the corresponding silver salts of 8 and 9, were converted to benzoylated derivatives 13, 14, 15, 26 16, 30 17 and 18 by treatment with benzoic anhydride (Bz 2 O) in ether, or using BzCl and pyridine or Et 3 N. Among these examples, we highlight the exceptionally simple preparation of benzoyl-Oxyma (13): addition of Bz 2 O to a 0.3 M solution of Oxyma in Et 2 O resulted in the formation of a precipitate within 1 min. Filtration and drying provided the pure reagent.…”

“…CH 2 Cl 2 and THF were dried over alumina according to the method of Pangborn et al38 Oxyma (ethyl 2-hydroximino-2-cyanoacetate, 6) was purchased from Sigma-Aldrich. The synthesis of various oximes and oxime benzoates has been reported previously: 8,25 9,26 10, 27 11, 28 12, 29 15, 26 and 16. ; HRMS [M + Na] + calcd for C 14 H 14 N 2 O 4 Na m/z 297.0846, found 297.0847. ; HRMS [M + Na] + calcd for C 13 H 11 NO 6 Na m/z 300.0479, found 297.0478. -phenylbenzyl benzoate 20 as a white solid, m. p. 62-63 °C (lit.…”