caa a22 4500 605529256 CHVBK 20210128100817.0 cr unu---uuuuu 210128e20150701xx s 000 0 eng 10.1134/S1070428015070143 doi (NATIONALLICENCE)springer-10.1134/S1070428015070143 Steric hindrances to the cycloaddition of ( Z )-1-arylmethylidene-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides to N -arylmaleimides [Elektronische Daten] [Yu. Koptelov, D. Antuganov, A. Molchanov, R. Kostikov] Sterically hindered cycloaddition of (Z)-1-arylmethylidene-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ides to 4-mono- and 2,6-disubstituted N-arylmaleimides requires prolonged heating (40-60 h) at ~150-155°C and yields mixtures of diastereoisomeric cycloadducts. The observed diastereoselectivity is determined by both electronic and steric interactions, depending on the nature and position of substituents in the azomethine imine and maleimide. The reactions of (Z)-1-(2,6-dichlorobenzylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide with 4-substituted N-arylmaleimides give mainly the corresponding cis adducts as a result of preferential exo attack by the dipolarophile, whereas trans adducts predominate in the cycloaddition of (Z)-1-(4-X-benzylidene)-5,5-dimethyl-3-oxopyrazolidin-1-ium-2-ide and (Z)-1-(2,6-dichlorobenzylidene)-5,5-dimethyl-3-oxopyrazolidin- 1-ium-2-ide to 2,6-disubstituted N-arylmaleimides. Pleiades Publishing, Ltd., 2015 Koptelov Yu St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut Antuganov D. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut Molchanov A. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut Kostikov R. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut Russian Journal of Organic Chemistry Pleiades Publishing 51/7(2015-07-01), 972-981 1070-4280 51:7<972 2015 51 11178 https://doi.org/10.1134/S1070428015070143 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1134/S1070428015070143 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Koptelov Yu St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut NATIONALLICENCE 700 1- Antuganov D. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut NATIONALLICENCE 700 1- Molchanov A. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut NATIONALLICENCE 700 1- Kostikov R. St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia aut NATIONALLICENCE 773 0- Russian Journal of Organic Chemistry Pleiades Publishing 51/7(2015-07-01), 972-981 1070-4280 51:7<972 2015 51 11178