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Abstract Thesynandantiisomers of [FeIV(O)(TMC)]2+(TMC=tetramethylcyclam) represent the first isolated pair of synthetic non‐heme oxoiron(IV) complexes with identical ligand topology, differing only in the position of the oxo unit bound to the iron center. Both isomers have previously been characterized. Reported here is that thesynisomer [FeIV(Osyn)(TMC)(NCMe)]2+(2) converts into itsantiform [FeIV(Oanti)(TMC)(NCMe)]2+(1) in MeCN, an isomerization facilitated by water and monitored most readily by1H NMR and Raman spectroscopy. Indeed, when H218O is introduced to2, the nascent1becomes18O‐labeled. These results provide compelling evidence for a mechanism involving direct binding of a water moleculetransto the oxo atom in2with subsequent oxo–hydroxo tautomerism for its incorporation as the oxo atom of1. The nonplanar nature of the TMC supporting ligand makes this isomerization an irreversible transformation, unlike for their planar heme counterparts.
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Syn vs. Anti? What Controls Addition Stereochemistry in Chlorolactonization
Abstract The stereochemistry of the uncatalyzed chlorolactonization of 4‐phenylpent‐4‐enoic acid at room temperature was examined to probe the reaction's intrinsic diastereoselectivities as a function of chlorenium ion donor, solvent polarity, and reactant concentration ranges. Kinetic studies using Variable Time Normalization Analysis (VTNA) revealed differing reaction orders for thesynandantialkene addition processes. Aided and illustrated by quantum chemical modeling, this detailed mechanistic analysis of the substrate's intrinsic chlorolactonization reactions points to concerted AdE3‐type paths for bothsynandantiadditions. By illuminating the factors selecting forsyn‐vsanti‐addition paths, the results provide key reference points for future studies of stereocontrol in halofunctionalization reactions.
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- Award ID(s):
- 2154923
- PAR ID:
- 10573875
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 31
- Issue:
- 1
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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