sorry, we can't preview this file
...but you can still download om8b00285_si_002.xyz
Mechanistic Insights into the ReIO2(PPh3)2‑Promoted Reductive Coupling of Alcohols
datasetposted on 19.07.2018, 14:21 by Camille Boucher-Jacobs, Peng Liu, Kenneth M. Nicholas
Datasets usually provide raw data for analysis. This raw data often comes in spreadsheet form, but can be any collection of data, on which analysis can be performed.
A mechanistic investigation of the reductive coupling of benzylic and allylic alcohols by triphenylphosphine catalyzed by ReIO2(PPh3)2 (1) is disclosed utilizing (1) stoichiometric reaction studies of 1 with alcohols, with PPh3 and with OPPh3; (2) rate law determination of the reaction of benzhydrol with PPh3 catalyzed by 1; (3) substrate structure-dependent reactivity/selectivity studies; and (4) DFT computational analysis of various potential reaction pathways in the benzyl alcohol/PPh3 reaction. In situ NMR monitoring of reactions of 1 with PPh3 and various alcohols demonstrate (a) facile, reversible PPh3 dissociation from 1; (b) association of various alcohols to form Re-alcohol/alkoxide complexes, (Ph3P)IReO2(ROH) and (Ph3P)IReO(OH)(OR); and (c) thermal conversion of these alcohol(ate)-rhenium complexes to Ph2CH–CHPh2 and OPPh3 at >50 °C. Under pseudo-first-order conditions, the initial rate kinetics of reductive coupling of Ph2CHOH/PPh3 catalyzed by 1 shows (a) a reaction rate that is first-order each in ROH, catalyst and first-order (or higher) in PPh3 and (b) the reaction is inhibited by OPPh3. Alcohol structure effects show (a) relative reactivity of sec-, tert-benzylic = allylic > prim-benzylic/allylic ≫ sec-, prim-alkyl and (b) low regioselectivity of the dimers from unsymmetrical allylic alcohols. A DFT computational study of the reaction of benzyl alcohol/PPh3 with 1 reveals a preferred pathway involving: (a) formation of rhenium–alcohol and −alkoxide intermediates, (Ph3P)IReO2(ROH) and (Ph3P)IReO(OH)(OR); (b) reduction of the latter by PPh3 to form (OPPh3)(Ph3P)IRe(OH)(OBn) (E); (c) association of a second BnOH with E to give (Ph3P)IRe(OBn)2 (K); (d) facile dissociation of a benzyl radical from K by C–O homolysis; and (e) a second rhenium–O–Bn homolysis from (PPh3)IRe(H2O)(OBn) (O), giving bibenzyl via benzyl radical recombination and regenerating (PPh3)ReIO2.