000126310 001__ 126310 000126310 005__ 20241125101153.0 000126310 0247_ $$2doi$$a10.1039/d3ob00284e 000126310 0248_ $$2sideral$$a133629 000126310 037__ $$aART-2023-133629 000126310 041__ $$aeng 000126310 100__ $$aSierra, Sonia 000126310 245__ $$aSynthesis of 1,2-diaminotruxinic d-cyclobutanes by BF<sub>3</sub>-controlled [2 + 2]-photocycloaddition of 5(4<i>H</i>)-oxazolones and stereoselective expansion of d-cyclobutanes to give highly substituted pyrrolidine-2,5-dicarboxylates 000126310 260__ $$c2023 000126310 5060_ $$aAccess copy available to the general public$$fUnrestricted 000126310 5203_ $$aThe irradiation of (Z)-4-arylidene-5(4H)-oxazolones 1a–1u with blue light (465 nm) in the presence of the photosensitizer [Ru(bpy)3](BF4)2 (2.5 mol%) and the Lewis acid BF3·OEt2 (2 equiv.) in deoxygenated methanol at room temperature affords the corresponding 1,2-diaminotruxinic cyclobutane bis-amino esters 2a–2u stereoselectively as the δ-isomer. Characterization of cyclobutanes 2 shows that the photocycloaddition takes place by the coupling of two Z-oxazolones in a head-to-head 1,2-anti way. This change in the orientation of the coupling is promoted by O- or/and N-bonding of the BF3 additive. The δ-cyclobutanes 2 undergo a ring expansion when heated in methanol in the presence of NaOMe (1/1 molar ratio) to give densely substituted pyrrolidine-2,5-dicarboxylates 3 in a regio- and stereoselective way. The mechanism of the cyclobutane-to-pyrrolidine ring expansion has been elucidated using DFT methods. 000126310 536__ $$9info:eu-repo/grantAgreement/ES/DGA/E11-20R$$9info:eu-repo/grantAgreement/ES/DGA/E19-20R$$9info:eu-repo/grantAgreement/ES/MCINN-FEDER/PGC2018-093451-B-I00$$9info:eu-repo/grantAgreement/ES/MICINN AEI PID2019-110008GB-I00$$9info:eu-repo/grantAgreement/ES/MICINN/PID2019-106394GB-I00 000126310 540__ $$9info:eu-repo/semantics/openAccess$$aby-nc$$uhttp://creativecommons.org/licenses/by-nc/3.0/es/ 000126310 590__ $$a2.9$$b2023 000126310 592__ $$a0.607$$b2023 000126310 591__ $$aCHEMISTRY, ORGANIC$$b13 / 58 = 0.224$$c2023$$dQ1$$eT1 000126310 593__ $$aOrganic Chemistry$$c2023$$dQ2 000126310 593__ $$aPhysical and Theoretical Chemistry$$c2023$$dQ2 000126310 593__ $$aBiochemistry$$c2023$$dQ3 000126310 594__ $$a5.5$$b2023 000126310 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000126310 700__ $$aLópez, Rosa 000126310 700__ $$aGómez-Bengoa, Enrique 000126310 700__ $$0(orcid)0000-0002-0444-996X$$aFalvello, Larry R.$$uUniversidad de Zaragoza 000126310 700__ $$aUrriolabeitia, Esteban P. 000126310 7102_ $$12010$$2760$$aUniversidad de Zaragoza$$bDpto. Química Inorgánica$$cÁrea Química Inorgánica 000126310 773__ $$g21, 15 (2023), 3203-3213$$pOrg. biomol. chem.$$tOrganic & Biomolecular Chemistry$$x1477-0520 000126310 8564_ $$s1931034$$uhttps://zaguan.unizar.es/record/126310/files/texto_completo.pdf$$yVersión publicada 000126310 8564_ $$s2660827$$uhttps://zaguan.unizar.es/record/126310/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000126310 909CO $$ooai:zaguan.unizar.es:126310$$particulos$$pdriver 000126310 951__ $$a2024-11-22-12:07:44 000126310 980__ $$aARTICLE