{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T07:26:31Z","timestamp":1779175591511,"version":"3.51.4"},"reference-count":27,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2022,10,17]],"date-time":"2022-10-17T00:00:00Z","timestamp":1665964800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>A series of N-Boc ketimines derived from pyrazolin-5-ones have been used as electrophiles in enantioselective Mannich reactions with different 1,3-dicarbonyl compounds. This method provides a direct pathway to access the 4-amino-5-pyrazolone derivatives bearing a quaternary substituted stereocenter and containing two privileged structure motifs, the \u03b2-diketone and pyrazolinone substructures. The adducts were obtained in excellent yields (up to 90%) and enantioselectivities (up to 94:6 er) by employing a very low loading of 2 mol% of a quinine-derived bifunctional squaramide as an organocatalyst for a wide range of substrates. In addition, the utility of the obtained products was demonstrated through one step transformations to enantioenriched diheterocyclic systems (4-pyrazolyl-pyrazolone and 4-isoxazolyl-pyrazolone), potentially promising candidates for drug discovery.<\/jats:p>","DOI":"10.3390\/molecules27206983","type":"journal-article","created":{"date-parts":[[2022,10,18]],"date-time":"2022-10-18T00:31:01Z","timestamp":1666053061000},"page":"6983","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Squaramide-Catalyzed Asymmetric Mannich Reaction between 1,3-Dicarbonyl Compounds and Pyrazolinone Ketimines: A Pathway to Enantioenriched 4-Pyrazolyl- and 4-Isoxazolyl-4-aminopyrazolone Derivatives"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2368-2150","authenticated-orcid":false,"given":"Marta","family":"Gil-Ord\u00f3\u00f1ez","sequence":"first","affiliation":[{"name":"GIR SintACat, Instituto CINQUIMA and Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Bel\u00e9n 7, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3121-4074","authenticated-orcid":false,"given":"Camille","family":"Aubry","sequence":"additional","affiliation":[{"name":"GIR SintACat, Instituto CINQUIMA and Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Bel\u00e9n 7, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cristopher","family":"Ni\u00f1o","sequence":"additional","affiliation":[{"name":"GIR SintACat, Instituto CINQUIMA and Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Bel\u00e9n 7, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1941-6981","authenticated-orcid":false,"given":"Alicia","family":"Maestro","sequence":"additional","affiliation":[{"name":"GIR SintACat, Instituto CINQUIMA and Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Bel\u00e9n 7, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0595-3789","authenticated-orcid":false,"given":"Jos\u00e9 M.","family":"Andr\u00e9s","sequence":"additional","affiliation":[{"name":"GIR SintACat, Instituto CINQUIMA and Departamento de Qu\u00edmica Org\u00e1nica, Facultad de Ciencias, Universidad de Valladolid, Paseo de Bel\u00e9n 7, 47011 Valladolid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1466","DOI":"10.1002\/adsc.202001307","article-title":"Catalytic Asymmetric Aza-Diels-Alder Reaction: Pivotal Milestones and Recent Applications to Synthesis of Nitrogen-Containing Heterocycles","volume":"363","author":"Vinogradov","year":"2021","journal-title":"Adv. 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