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Definitive Proof for the Operation of Isotopically Sensitive Branching (‘Metabolic Switching’) in Fe I ‐Mediated CH Bond Activation in the Gas Phase Short Communication
Author(s) -
Seemeyer Katrin,
Prüsse Tilmann,
Schwarz Helmut
Publication year - 1993
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19930760420
Subject(s) - chemistry , stereospecificity , dehydrogenation , branching (polymer chemistry) , kinetic isotope effect , gas phase , isotope , stereochemistry , organic chemistry , deuterium , catalysis , physics , quantum mechanics
Rigorous regio‐ and stereospecific labeling experiments are performed to demonstrate the operation of the previously suggested operation of ‘isotopically sensitive branching’ in Fe I ‐mediated CH bond activation. For the hexane‐1,6‐diol/Fe + ‐complex, it is shown that dehydrogenation involves specifically the central C(3)/C(4) position, and the study of the stereospecifically labeled D , L ‐ and meso‐[3,4‐D 2 ]‐isotompomers 1e and 1f demonstrates that dehydrogenation proceedes via two competing pathways ( i.e. ‘anti’‐ vs. ‘syn ’‐route). The contribution of these routes to the product formation is – due to a kinetic isotope effect – controlled by the relative configuration at the labeled positions C(3)/C(4) . For the D , L ‐form 1e , we estimate a ratio of 49:1 in favor of the ‘ anti ’‐route; due to an isotope effect, this ratio drops to 4.3:1 for the meso ‐form 1f .