Russian Journal of Organic Chemistry, Vol. 41, No. 4, 2005, pp. 620–622. Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 629–631. Original Russian Text Copyright © 2005 by Vs. Nikolaev, Hennig, Croft, Schulze, Kostikov, V. Nikolaev. 1070-4280/05/4104-0620 © 2005 Pleiades Publishing, Inc. Ethyl Diazoacetate in Catalytic Reactions with Imides: Experimental and Calculation Data Vs. V. Nikolaev 1 , L. Hennig 2 , A. K. Croft 3 , B. Schulze 2 , R. R. Kostikov 1 , and V. A. Nikolaev 1 1 St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia e-mail: vnikola@VN6646.spb.edu 2 Universität Leipzig, Institut für organische Chemie, Leipzig, Germany 3 University of Wales, Department of Chemistry, Bangor, Great Britain Received November 30, 2004 SHORT COMMUNICATIONS In continuation of our studies in the field of catalytic reactions of diazo carbonyl compounds with imides having an NH group [1], the present com- munication reports on the effect of the reactant struc- ture on the direction of catalytic decomposition of ethyl diazoacetate in the presence of saccharin (Ia), phthalimide (Ib), and maleimide (Ic). In addition, we performed calculations of the stability of O- and N-ylides as possible intermediates. Catalytic decomposition of ethyl diazoacetate (II) with dirhodium tetraacetate [2] in the presence of saccharin (Ia) and phthalimide (Ib) afforded only the corresponding ethoxycarbonylmethyl imidates IIIa and IIIb, respectively, resulting from O-alkylation of the carbonyl group in the substrate, as well as diethyl maleate and dimethyl fumarate formed by dimerization of intermediate ethoxycarbonylcarbene (Scheme 1). are stabilized via intramolecular [1,4]-migration of the imide hydrogen atom [4]. An analogous reaction of diazo ester II with male- imide (Ic) gave cycloadduct IV due to participation of two maleimide molecules (Scheme 2). The structure of IV was determined by 1 H and 13 C NMR spectroscopy using APT pulse sequence and COSY, HMQC, HMBC, and NOESY techniques. The exo configura- tion of IV was confirmed by NOE experiments on 1-H, 5-H, and 4-H (δ 3.73, 3.85, and 4.81 ppm, respec- tively). Spirocyclic compound IV is likely to be formed via intermolecular 1,3-cycloaddition of the primary adduct, carbonyl ylide B, at the double bond of the second maleimide molecule. Our experimental data indicate that the attack by rhodium(II) intermediate A is directed at the carbonyl oxygen atom in imide substrate Ia–Ic to give carbonyl Scheme 1. X NH O Ia, Ib + N 2 =CHCOOEt II Rh 2 (OAc) 4 , CH 2 Cl 2 X N OCH 2 COOEt IIIa, IIIb X = SO 2 (a), CO (b). Obviously, as in the catalytic decomposition of diazo dicarbonyl compounds [1], the process involves intermediate formation of carbonyl ylides [3] which Scheme 2. N H O O Ic + L n Rh=CHCOOEt A –L n Rh N H O O CHCOOEt B Ic 5 1 8 HN 7 6 2 O 3 4 3' 4' 5' NH 1' O O O H H COOEt IV 2'