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Cornforth–Evans Transition States in Stereocontrolled Allylborations of Epoxy Aldehydes

Freund, Robert R. A.; Borg, Matthias; Gaissmaier, Daniel; Schlosser, Robin; Jacob, Timo; Arndt, Hans‐Dieter

Abstract:
Allylboration reactions rank among the most reliable tools in organic synthesis. Herein, we report a general synthesis of trifunctionalized allylboronates and systematic investigations of their stereocontrolled transformations with substituted aldehyde substrates, in order to efficiently access diverse, highly substituted target substrates. A peculiar transition in stereocontrol was observed from the polar Felkin–Anh (PFA) to the Cornforth–Evans (CE) model for alkoxy‐ and epoxy‐substituted aldehydes. CE‐type transition states were uniformly identified as minima in advanced, DFT‐based computational studies of allylboration reactions of epoxy aldehydes, conforming well to the experimental data, and highlighting the underestimated relevance of this model. Furthermore, a mechanism‐based rationale for the substitution pattern of the epoxide was delineated that ensures high levels of stereocontrol and renders α,β‐epoxy aldehydes generally applicable substrates for target synthesis.

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Verlagsausgabe §
DOI: 10.5445/IR/1000122031
Veröffentlicht am 24.07.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 14.07.2020
Sprache Englisch
Identifikator ISSN: 0947-6539, 1521-3765
KITopen-ID: 1000122031
Erschienen in Chemistry - a European journal
Band 26
Heft 39
Seiten 8639–8650
Vorab online veröffentlicht am 02.04.2020
Nachgewiesen in Scopus
Web of Science
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