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Transition metal-catalysed [2+2+2] cycloaddition reactions. Methodology and mechanism

The transition-metal catalysed [2+2+2] cycloaddition reaction is a highly efficient synthetic tool that allows six-membered polysubstituted carbo- and heterocyclic derivatives to be obtained in an atom economy process. This doctoral thesis is based on methodological and mechanistic studies of the rhodium(I)-catalysed [2+2+2] cycloaddition reaction. In particular, the use of hemilabile S-stereogenic and P-stereogenic ligands for the rhodium-catalysed [2+2+2] cycloaddition is described. The activity of these new catalytic systems is evaluated in the cycloaddition of three alkynes and in the enantioselective cycloaddition of enediynes to obtain chiral cyclohexa-1,3-dienes. Moreover, the participation of Baylis-Hillman adducts as alkene moieties for the partially intramolecular [2+2+2] cycloaddition is described for the synthesis of a set of enantioenriched bicyclic cyclohexadienes featuring a quaternary stereogenic centre. Finally, the mechanistic study of the [2+2+2] cycloaddition of alkynes by electrospray ionization mass spectrometry and DFT calculations is performed.

La reacci贸 de cicloaddici贸 [2+2+2] catalitzada per metalls de transici贸 茅s una eina molt eficient que permet la formaci贸 de derivats carbo- i heteroc铆clics polisubstitu茂ts de sis membres en un proc茅s d鈥檈conomia at貌mica. Aquesta tesi doctoral es basa en l鈥檈studi metodol貌gic i mecan铆stic de les reaccions de cicloaddici贸 [2+2+2] catalitzades per rodi(I). Concretament, es descriu l鈥櫭簊 de lligands hemil脿bils S-estereog猫nics i P-estere貌genics per a la reacci贸 de cicloaddici贸 [2+2+2] catalitzada per rodi d鈥檃lquins i tamb茅 en la cicloaddici贸 enantioselectiva d鈥檈ndi茂ns per a l鈥檕btenci贸 de ciclohexadiens quirals. Tamb茅 s鈥檈studia la participaci贸 d鈥檃dductes de Baylis-Hillman com a substrats olef铆nics d鈥檃questes reaccions permetent la s铆ntesi de ciclohexadiens quirals bic铆clics amb un centre estereog猫nic quaternari. Finalment, es presenta l鈥檈studi mecan铆stic de les reaccions de cicloaddici贸 [2+2+2] d鈥檃lquins a trav茅s de l鈥檈spectrometria de masses amb ionitzaci贸 per electroesprai i c脿lculs DFT.

Universitat de Girona

Manager: Roglans i Ribas, Anna
Pla i Quintana, Anna
Other contributions: Universitat de Girona. Departament de Qu铆mica
Author: Parera Brians贸, Magda
Date: 2014 May 20
Abstract: The transition-metal catalysed [2+2+2] cycloaddition reaction is a highly efficient synthetic tool that allows six-membered polysubstituted carbo- and heterocyclic derivatives to be obtained in an atom economy process. This doctoral thesis is based on methodological and mechanistic studies of the rhodium(I)-catalysed [2+2+2] cycloaddition reaction. In particular, the use of hemilabile S-stereogenic and P-stereogenic ligands for the rhodium-catalysed [2+2+2] cycloaddition is described. The activity of these new catalytic systems is evaluated in the cycloaddition of three alkynes and in the enantioselective cycloaddition of enediynes to obtain chiral cyclohexa-1,3-dienes. Moreover, the participation of Baylis-Hillman adducts as alkene moieties for the partially intramolecular [2+2+2] cycloaddition is described for the synthesis of a set of enantioenriched bicyclic cyclohexadienes featuring a quaternary stereogenic centre. Finally, the mechanistic study of the [2+2+2] cycloaddition of alkynes by electrospray ionization mass spectrometry and DFT calculations is performed.
La reacci贸 de cicloaddici贸 [2+2+2] catalitzada per metalls de transici贸 茅s una eina molt eficient que permet la formaci贸 de derivats carbo- i heteroc铆clics polisubstitu茂ts de sis membres en un proc茅s d鈥檈conomia at貌mica. Aquesta tesi doctoral es basa en l鈥檈studi metodol貌gic i mecan铆stic de les reaccions de cicloaddici贸 [2+2+2] catalitzades per rodi(I). Concretament, es descriu l鈥櫭簊 de lligands hemil脿bils S-estereog猫nics i P-estere貌genics per a la reacci贸 de cicloaddici贸 [2+2+2] catalitzada per rodi d鈥檃lquins i tamb茅 en la cicloaddici贸 enantioselectiva d鈥檈ndi茂ns per a l鈥檕btenci贸 de ciclohexadiens quirals. Tamb茅 s鈥檈studia la participaci贸 d鈥檃dductes de Baylis-Hillman com a substrats olef铆nics d鈥檃questes reaccions permetent la s铆ntesi de ciclohexadiens quirals bic铆clics amb un centre estereog猫nic quaternari. Finalment, es presenta l鈥檈studi mecan铆stic de les reaccions de cicloaddici贸 [2+2+2] d鈥檃lquins a trav茅s de l鈥檈spectrometria de masses amb ionitzaci贸 per electroesprai i c脿lculs DFT.
Format: application/pdf
Document access: http://hdl.handle.net/10803/145035
Language: eng
Publisher: Universitat de Girona
Rights: ADVERTIMENT. L鈥檃cc茅s als continguts d鈥檃questa tesi doctoral i la seva utilitzaci贸 ha de respectar els drets de la persona autora. Pot ser utilitzada per a consulta o estudi personal, aix铆 com en activitats o materials d鈥檌nvestigaci贸 i doc猫ncia en els termes establerts a l鈥檃rt. 32 del Text Ref贸s de la Llei de Propietat Intel路lectual (RDL 1/1996). Per altres utilitzacions es requereix l鈥檃utoritzaci贸 pr猫via i expressa de la persona autora. En qualsevol cas, en la utilitzaci贸 dels seus continguts caldr脿 indicar de forma clara el nom i cognoms de la persona autora i el t铆tol de la tesi doctoral. No s鈥檃utoritza la seva reproducci贸 o altres formes d鈥檈xplotaci贸 efectuades amb finalitats de lucre ni la seva comunicaci贸 p煤blica des d鈥檜n lloc ali猫 al servei TDX. Tampoc s鈥檃utoritza la presentaci贸 del seu contingut en una finestra o marc ali猫 a TDX (framing). Aquesta reserva de drets afecta tant als continguts de la tesi com als seus resums i 铆ndexs.
Subject: Qu铆mica org脿nica
Title: Transition metal-catalysed [2+2+2] cycloaddition reactions. Methodology and mechanism
Type: doctoralThesis
Repository: TDX

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