Novel dipolarophiles and dipoles in the metal-catalyzed enantioselective 1,3-dipolar cycloaddition of azomethine ylides

Abstract

The catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides constitutes one of the most powerful and atom economical methods for the enantioselective construction of pyrrolidines. This article highlights the recent developments in this area, with special focus on contributions improving the structural scope at the dipolarophile and azomethine ylide partners.

Asymmetric 1,3-Dipolar Cycloadditons of Stabilized Azomethine Ylides with Nitroalkenes

“…Such as it was mentioned before, since 2002 many contributions employing chiral Lewis acids or chiral organocatalysts have been compiled in the literature [13][14][15][16][17][18][19][20]. The number of catalysts and their efficiency contribute to the preparation of multiple and sophisticated molecules with well defined absolute configuration.…”

“…These applications and properties of the mentioned compounds represent a small part of the enormous interest of prolines and pyrrolidines in many scientific areas [10][11][12]. All this series of compounds C, bearing attached a nitro group, can be prepared in a straightforward manner employing asymmetric 1,3-dipolar cycloadditions (1, between stabilized azomethine ylides generated from imino esters A or even its corresponding iminium salt A' and nitroalkenes B [13][14][15][16][17][18][19][20] employing very mild reaction conditions according to the retrosynthetic pathway shown in (Scheme 1). The most employed 1,3-dipole in the literature is the azomethine ylide [21][22][23][24][25][26][27], which can be generated from diverse routes [22].…”

Recent advances in the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides

“…8 The present feature article focuses on the contributions achieved from 2011 to April 2014 with special emphasis on the results involving novel dipolarophiles and azomethine ylide partners. Finally, we also present the recent developments involving organocatalysis.…”

Coinage metal complexes as chiral catalysts for 1,3-dipolar cycloadditions

“…Good chemoselectivity, good functional group compatibility, stability, are the main features of noble metal complexes which are crucial for application in complex molecular environments. One of the representative examples concerns the synthesis of enantiomerically enriched prolines [4,5,6] through the catalytic enantioselective 1,3-dipolar cycloadditions (1, [7,8,9,10,11,12,13,14]between azomethine ylide and alkenes. In fact, silver and copper catalyzed 1,3-DC are very well known and constitute the most reliable, and direct enantioselective methodology to built up to four stereogenic centers of the resulting proline derivatives [6,15,16,17,18], in only one operation step.…”