[en] AbstractIn this dissertation, our work on the study of chiral secondary amines aspromoters in enantioselective organocatalytic cascade reactions towards theasymmetric synthesis of different substituted hetero- and carbocycles is presented.In this sense, we have developed an efficient methodology for theconstruction of hexahydrofuro[3,4-c]furans containing four stereocenters by meansof an amine catalyzed oxa-Michael/aldol/hemiacetalization cascade reaction byreacting different , -unsaturated aldehydes with dihydroxyacetone underiminium/enamine catalysis. Remarkably, a high pKa oxygen pro-nucleophile hasbeen employed as functionalized Michael donor to initiate the conjugate process,which represents an important feature of this transformation. This methodology hasled to the formation of polysubstituted furofuranes in excellent yields and diastereoandenantioselectivities. Moreover, different related compounds can be accessedthrough the selective manipulation of the functionalities present within the obtainedadducts emphasising the potential of this methodology for the synthesis of usefulchiral building blocks. Additionally, this strategy has been extended to the use of Nprotected--aminoacetophenone for the synthesis of -lactams through aMichael/hemiaminalization cascade sequence.On the other hand, we have set up an enantioselective formal [2+2]cycloaddition reaction between enolizable , -unsaturated aldehydes andnitroalkenes towards the synthesis of highly substituted cyclobutanes. In thisparticular case, the combination of an , -diphenylprolinol derivative and anachiral thiourea was employed as the catalytic system, which was shown as apowerful activation strategy for the development of this reaction, affording productsin high yields and with excellent stereocontrol

[eu] LaburpenaDoktorego tesi honetan, estrategia organokatalitikoak aukeratu dira zenbaitinteres handiko konposatuen sintesi asimetrikoa aurrera eramateko. Zentzu honetan,kaskada erreakzioetan oinarritutako prozesuak diseinatu dira aminokatalizatzaileekeskaintzen duten aktibazio modu ezberdinak erabiliz etekin eta kontrolestereokimiko altuak lortuz.Lehenik, enantioaberastutako furofurano poliordezkatuak lortzeko sintesiaminokatalitikoa ikertu da dihidroxiazetona eta aldehido , -asegabetuak erabiliz.Kasu honetan, iminio eta enamina aktibazio motak konbinatu egin dira oxa-Michael/aldolika erreakzioa/hemiazetalizazioa kaskada prozesu enantioselektibo etaeraginkor bat aurrera eramanez. Era berean, lortutako produktuen aldakortasunsintetikoak zenbait eraldaketa kimiko burutzea ahalbidetu du metodologia honengarrantzi sintetikoa erakutsiz. Halaber, garatutako estrategia aminokatalitikoazabaltzeko asmoz, -aminoazetofenonaren erabilera frogatu da -laktamaezberdinak lortuz. Aldi berean, sintetizatutako heteroziklo hauek konposatu 1,4-dikarboniliko enantioaberats ezberdinetan eraldatu egin dira.Bestalde, [2+2] zikloadizio organokatalitiko formala aztertu da katalisikobalente eta ez kobalentea erabiliz. Horretarako, aminokatalizatzaile eta tioureazosatutako sistema katalitikoa aukeratu da, bi aktibazio modu hauen kooperazioaketekin eta kontrol estereokimiko altuak lortzea ahalbideratzen duela frogatuz.