Organic Chemistry: Current Research
Open Access

Multicomponent 1,3-dipolar cycloadditions of azomethine ylides

4^th European Organic Chemistry Congress

March 01-03, 2018 | London, UK

Carmen Najera

Universidad de Alicante, Spain

Scientific Tracks Abstracts: Organic Chem Curr Res

Abstract :

Multicomponent reactions (MCRs) are important processes from atom and step economy point of view. 1,3-Dipolar cycloadditions (1,3-DC) involving azomethine ylides and electrophilic alkenes are good examples for this type of transformation but are not so frequently described. In this lecture, the thermal and silver mediated multicomponent 1,3DC between ���±-amino esters, dipolarophiles and aldehydes will be considered. This 1,3-DC allows the synthesis of highly substituted pyrrolidines under conventional or MW heating. In general, 4,5-endo diastereoselectivity was mainly observed and 2,5-cis-cycloadducts are formed according to a W-shaped dipole. When this MCR was performed with 2-oxoaldehydes, the 1,3-DC takes place under silver acetate catalysis at rt [3b]. On the other hand, the multicomponent 1,3-dipolar cycloaddition between different proline esters, aldehydes and dipolarophiles afford highly substituted pyrrolizidines will also be described. The corresponding highly substituted pyrrolizidines are obtained in all cases with 2,5-trans-relative configuration between two electron-withdrawing groups and major endo-selectivity with 2,4-cis-relative configuration. The use of (2S,4R)-4hydroxyproline methyl ester hydrochloride allowed the synthesis of enantiomerically enriched pyrrolizidines. When pipecolic acid alkyl esters are used the corresponding indolizidines can be prepared under thermal reaction conditions. Recent publications 1. Brauch S, van Berkel S S, Westermann B (2013) Higher-order multicomponent reactions: beyond four reactants. Chem. Soc. Rev. 42, 4948-62. 2. (b) Science of Synthesis: Multicomponent Reactions; M���¼ller, T. J. J. Ed.; Thieme: Stuttgart, 2014. (c) Multicomponent Reactions: Concepts and Applications for Design and Synthesis, P���©rez-Herrera, R. and Marqu���©s-L���³pez, E. Eds.; WileyVCH: Weinheim, 2015. 3. N���¡jera, C.; Sansano, J. M.; Yus, M. J. Braz. Chem. Soc. 2010, 21, 377. 4. (a) Mancebo-Aracil, J.; N���¡jera, C.; Sansano, J. M. Org. Biomol. Chem. 2013, 11, 662. (b) Mancebo-Aracil, J.; Cayuelas, A.; N���¡jera, C.; Sansano, J. Tetrahedron 2015, 71, 8804. 5. (a) Mancebo-Aracil, J.; N���¡jera, C.; Sansano, J. Chem. Commun. 2013, 49, 11218. (b) Selva, V.; Larra���±aga, O.; Castell���³, L. M.; N���¡jera, C.; Sansano, J. M.; de C���³zar, A. J. Org. Chem. 2017, 82, 6298. 6. Castell���³, L. M.; Selva, V.; N���¡jera, C.; Sansano, J. M. Synthesis 2017, 49, 299. cnajera@ua.es