A Highly Enantio‐ and Diastereoselective Cu‐Catalyzed 1,3‐Dipolar Cycloaddition of Azomethine Ylides with Nitroalkenes

Abstract

Electronic properties of the ligands switch the diastereoselectivity in the Cu‐catalyzed 1,3‐dipolar cycloaddition of azomethine ylides to nitroalkenes: exo‐ or endo‐pyrrolidines were obtained with high diastereo‐ and enantioselectivities in the presence of different chiral (phosphanylferrocenyl)oxazoline ligands (e.g. 3 a, b).

Ferrocene-derived P,N ligands: synthesis and application in enantioselective catalysis

“…Using the same copper source and a similar ligand, Hou et al developed a 1,3-dipolar cycloaddition of nitroalkenes 73 with N-metalated azomethine ylides derived from 74 (Scheme 19) [91]. Variations on the nature of the aryl group on the phosphorus atom resulted in a dramatic change of the endo/exo selectivity: electron-rich phosphanes (76) promoted the formation of the exo-adduct as the sole product, while electron poor phosphanes (77) afforded mainly the endo-adduct.…”

X=Y–ZH compounds as potential 1,3-dipoles. Part 64: Synthesis of highly substituted conformationally restricted and spiro nitropyrrolidines via Ag(I) catalysed azomethine ylide cycloadditions

“…These latter results confirmed prior work by our group on proton-sponge effects in azomethine ylide formation. 11 An asymmetric catalytic version of 1,3-dipolar cycloaddition of nitroalkenes to an imino ester derived from glycine has been reported 12 as has microwave assisted synthesis of highly substituted nitroproline esters via 1,3-dipolar cycloaddition. 13 This paper describes our studies of the silver catalysed synthesis of nitropyrrolidines 3 and their derivatives 4,5 all of which proceed via endo-transition states.…”

Perspectives on Intermolecular Azomethine Ylide [3+2] Cycloadditions with Non-Electrophilic Olefins

“…7 The first catalytic enantioselective [3+2] cycloadditions were reported independently by Zhang 8 and Jørgensen 9 in 2002 (Scheme 2, b). Since then, countless contributions by Schreiber, 10 Carreira, 11 Carretero, 12 Zhou, 13 Hou, 14 Li, 15 Toste, 16 Kobayashi, 17 Nájera,18 Wang,19 Fukuzawa, 20 Arai, 21 Hu/Zheng, 22 Waldmann 23 and others have continuously pushed the limits of this chemistry. Comprehensive reviews have compiled these efforts, evidencing the dominance of Cu and Ag catalysts.…”