Postglobal Teacher Preparation: Border Thinking along the Global South through International Cross-Cultural Experiences (La Preparación Post Global del Maestro) (pp.76-96)

Preservice teachers’ international cross-cultural experiences can provide opportunities for the exploration of epistemic frontiers.  In this article we suggest that postglobal teacher preparation is a critically reflective approach that engages preservice teachers in border thinking, which allows for other ways of knowing while studying abroad.  Through international cross-cultural experiences, preservice teachers can recognize the disparate impacts of neoliberal economic globalization on educational and social equity within the metaphorical global South and the global North.  We examine the narratives constructed by preservice teachers through the reflection of their international cross-cultural experiences during a Honduras Study Abroad Program.  The article also explores the implications of a postglobal preparation for preservice teachers. (This article is provided in English only.)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Las experiencias culturales internacionales de aquellos que se preparan para ser maestros pueden proveer oportunidades para la exploración de fronteras epistémicas. Este artículo sugiere la preparación postglobal como una aproximación crítica y reflexiva que puede comprometer a los que se preparan para ser maestros hacia una forma fronteriza de pensamiento la cual les permite explorar otras formas de conocimiento. A través de esta experiencia los maestros en preparación también pueden tener la oportunidad de reconocer los impactos desiguales de la economía neoliberal y capitalista sobre diversas plataformas educacionales y sociales dentro de lo que metafóricamente se conocen como sur y norte globales. En este artículo se analizan narrativas construidas por los maestros en formación durante un programa de estudios internacionales en Honduras. Se exploran también implicancias para la preparación postglobal en la educación de maestros. (Este artículo se ofrece solamente en inglés.

Diastereoselective and Reversible Metallacycle Formation by Attack of a Pt-PR₂OH Group on a Coordinated Nitrile in Pt-Catalyzed Hydration

Kinetic resolution of the racemic nitrile CH(Et)(CN)(cyclo-N(CH2)3C(O)–) by catalytic asymmetric hydration to form the amide CH(Et)(C(O)NH2)(cyclo-N(CH2)3C(O)–) (Levetiracetam, Keppra) is an industrial biocatalytic process. To develop analogous procedures using chiral metal complexes as catalyst precursors, we investigated the mechanism and selectivity of the individual steps. Treatment of Pt(diphos)Cl2 with AgOTf and secondary phosphine oxides (SPOs) gave the cations [Pt(diphos)(PR'2OH)(Cl)][OTf] 1–6 containing either a chiral diphos ((R,R)-FerroLANE derivatives or (S,S)-Et-FerroTANE) or a chiral SPO tautomer ((R)-DMB-SPOPine). A second equiv of AgOTf yielded dicationic [Pt(diphos)(PR'2OH)][OTf]2 (9–12 and 14), with Fe–Pt interactions, or [Pt((S,S)-Et-FerroTANE)(PMe2OH)(OTf)][OTf] (13). Pt complexes 9 and 11–14 catalyzed hydration of the Keppra nitrile to the amide under mild conditions, with increased activity for smaller FerroLANE substituents. With water as the limiting reagent and an excess of racemic nitrile, no enantioselectivity in kinetic resolution by catalytic nitrile hydration was observed. Reaction of [Pt(R,R)-Me-FerroLANE)(PMe2OH)][OTf]2 (9) with enantiomerically enriched or racemic Keppra nitrile resulted in diastereoselective and reversible metallacycle formation to give [Pt((R,R)-Me-FerroLANE)(PMe2OC(R*)NH][OTf]2 (15, R* = CH(Et)(cyclo-N(CH2)3C(O)–)). Similar processes occurred with dications 10–11 and 13–14 with rac-Keppra nitrile, or with 9 and rac-PhCH(R)(CN) (R = Me, Et, i-Pr, Cy) or with racemic cyclo-Ph2CCH2CH(CN) to generate metallacycles 16–24. Metallacycle 15 reacted with water by attack at the PMe2O group, demonstrated by 18O-labeling studies, to yield the Keppra amide via an intermediate iminol complex [Pt((R,R)-Me-FerroLANE)(PMe2OH)(NHC(R*)(OH))][OTf]2 (25)

Diastereoselective and Reversible Metallacycle Formation by Attack of a Pt-PR₂OH Group on a Coordinated Nitrile in Pt-Catalyzed Hydration

Kinetic resolution of the racemic nitrile CH(Et)(CN)(cyclo-N(CH2)3C(O)–) by catalytic asymmetric hydration to form the amide CH(Et)(C(O)NH2)(cyclo-N(CH2)3C(O)–) (Levetiracetam, Keppra) is an industrial biocatalytic process. To develop analogous procedures using chiral metal complexes as catalyst precursors, we investigated the mechanism and selectivity of the individual steps. Treatment of Pt(diphos)Cl2 with AgOTf and secondary phosphine oxides (SPOs) gave the cations [Pt(diphos)(PR'2OH)(Cl)][OTf] 1–6 containing either a chiral diphos ((R,R)-FerroLANE derivatives or (S,S)-Et-FerroTANE) or a chiral SPO tautomer ((R)-DMB-SPOPine). A second equiv of AgOTf yielded dicationic [Pt(diphos)(PR'2OH)][OTf]2 (9–12 and 14), with Fe–Pt interactions, or [Pt((S,S)-Et-FerroTANE)(PMe2OH)(OTf)][OTf] (13). Pt complexes 9 and 11–14 catalyzed hydration of the Keppra nitrile to the amide under mild conditions, with increased activity for smaller FerroLANE substituents. With water as the limiting reagent and an excess of racemic nitrile, no enantioselectivity in kinetic resolution by catalytic nitrile hydration was observed. Reaction of [Pt(R,R)-Me-FerroLANE)(PMe2OH)][OTf]2 (9) with enantiomerically enriched or racemic Keppra nitrile resulted in diastereoselective and reversible metallacycle formation to give [Pt((R,R)-Me-FerroLANE)(PMe2OC(R*)NH][OTf]2 (15, R* = CH(Et)(cyclo-N(CH2)3C(O)–)). Similar processes occurred with dications 10–11 and 13–14 with rac-Keppra nitrile, or with 9 and rac-PhCH(R)(CN) (R = Me, Et, i-Pr, Cy) or with racemic cyclo-Ph2CCH2CH(CN) to generate metallacycles 16–24. Metallacycle 15 reacted with water by attack at the PMe2O group, demonstrated by 18O-labeling studies, to yield the Keppra amide via an intermediate iminol complex [Pt((R,R)-Me-FerroLANE)(PMe2OH)(NHC(R*)(OH))][OTf]2 (25)