Fairlamb, I.J.S., Grant, S., Tommasi, S. et al. (5 more authors) (2006) Phosphinite Ligand Effects in Palladium(II)-Catalysed Cycloisomerisation of 1,6-Dienes: Bicyclo[3.2.0]heptanyl Diphosphinite (B[3.2.0]DPO) Ligands Exhibit Flexible Bite Angles, an Effect Derived from Conformational Changes (exo- or endo-Envelope) in the Bicyclic Ligand Scaffold. Advanced Synthesis & Catalysis, 348 (16-17). pp. 2515-2530. ISSN 1615-4150
Abstract
Changes in bidentate ligand structure significantly affect catalytic activity in mono-cationic Pd(II)-catalysed 1,6-diene cycloisomerisation processes to give cyclopentene products. A bicyclo[3.2.0]heptanyl diphosphinite ligand (B[3.2.0]DPO, 3) is the first phosphorus-based bidentate ligand capable of promoting regioselective 1,6-diene cycloisomerisation. Trace quantities of water are essential for catalytic activity, as is the precise order of mixing of 1,6-diene, Pd(II) pro-catalyst and additives. Conformational changes in the ligand backbone seem to be important in stabilising the active catalyst species, assumed to be a cationic Pd(II) hydride species. DFT calculations support a change in bite angle on the cationic Pd(II) hydride species from circa 90° (cis) to 170° (trans); in the latter geometry an agostic interaction of the C4 endo hydrogen of the bicyclic ring-system with Pd(II) stabilises the cationic metal centre. This unique ligand property could be exploited in other transition metal catalysed processes.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Keywords: | anion effects • CC bond formation • cyclization • isomerization • palladium |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Chemistry (York) |
Depositing User: | York RAE Import |
Date Deposited: | 28 Aug 2009 10:55 |
Last Modified: | 28 Aug 2009 10:55 |
Published Version: | http://dx.doi.org/10.1002/adsc.200600346 |
Status: | Published |
Publisher: | John Wiley & Sons |
Identification Number: | 10.1002/adsc.200600346 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:5536 |