The configurational stability of four chiral 2,7-dihydro-1-phenyl-phosphepine-oxides 1a-4a (Figure 1), differing for the nature of the aromatic rings (carbocyclic or heterocyclic, six- or five-membered) constituting the stereogenic scaffold have been investigated. Unknown compound 4a was fully characterized by single crystal X-ray analysis. The tendency to enantiomerize has been determined by circular dichroism and on-column enantioselective HPLC methods. Biphenine-oxide 1a was found the only unstable compound at room temperature, displaying an enantiomerization barrier of about 20 kcal mol-1. Also the corresponding phosphanes 1b-4b have been considered in order to perform a comparative evaluation of their electronic availability, which is a crucial parameter affecting both the catalytic activity and stereoselection ability of their metal complexes. Unknown bithienophosphepine 4b was fully characterized by single crystal X-ray analysis. The quantitative evaluation of the electronic properties was performed by voltammetry, using the electrochemical oxidative peak potential as probe: the higher the value, the electron-poorer the phosphane. The electronic availability was found to decrease along to the sequence: 2b, 4b, 3b, 1b. E.Alberico, S.Karandikar, S.Gladiali, ChemCatChem 22, 2010, 1395 and references therein.

1,3,7,9-tetramethyl-5-phenyl-5,6-dihydro-4H-thieno[3',4':5,6]phosphepino[3,4 c]thiophene. Electronic and Steric Effects on the Catalytic Properties of the Metal Complexes of a New Chiral 2,7-Dihydro-1-Phenyl-Phosphepine / T. Benincori, V. Bonometti, R. Cirilli, R. Ferretti, P. Mussini, M. Pierini, T. Pilati, S. Rizzo, F. Sannicolò, L. Vaghi. ((Intervento presentato al 10. convegno Congresso del Gruppo Interdivisionale di Chimica Organometallica tenutosi a Padova, Italia nel 2012.

1,3,7,9-tetramethyl-5-phenyl-5,6-dihydro-4H-thieno[3',4':5,6]phosphepino[3,4 c]thiophene. Electronic and Steric Effects on the Catalytic Properties of the Metal Complexes of a New Chiral 2,7-Dihydro-1-Phenyl-Phosphepine

V. Bonometti
Secondo
;
P. Mussini;F. Sannicolò
Penultimo
;
2012

Abstract

The configurational stability of four chiral 2,7-dihydro-1-phenyl-phosphepine-oxides 1a-4a (Figure 1), differing for the nature of the aromatic rings (carbocyclic or heterocyclic, six- or five-membered) constituting the stereogenic scaffold have been investigated. Unknown compound 4a was fully characterized by single crystal X-ray analysis. The tendency to enantiomerize has been determined by circular dichroism and on-column enantioselective HPLC methods. Biphenine-oxide 1a was found the only unstable compound at room temperature, displaying an enantiomerization barrier of about 20 kcal mol-1. Also the corresponding phosphanes 1b-4b have been considered in order to perform a comparative evaluation of their electronic availability, which is a crucial parameter affecting both the catalytic activity and stereoselection ability of their metal complexes. Unknown bithienophosphepine 4b was fully characterized by single crystal X-ray analysis. The quantitative evaluation of the electronic properties was performed by voltammetry, using the electrochemical oxidative peak potential as probe: the higher the value, the electron-poorer the phosphane. The electronic availability was found to decrease along to the sequence: 2b, 4b, 3b, 1b. E.Alberico, S.Karandikar, S.Gladiali, ChemCatChem 22, 2010, 1395 and references therein.
Settore CHIM/06 - Chimica Organica
Settore CHIM/02 - Chimica Fisica
Settore CHIM/01 - Chimica Analitica
Società Chimica Italiana
http://www.chimica.unipd.it/cogico2012/
1,3,7,9-tetramethyl-5-phenyl-5,6-dihydro-4H-thieno[3',4':5,6]phosphepino[3,4 c]thiophene. Electronic and Steric Effects on the Catalytic Properties of the Metal Complexes of a New Chiral 2,7-Dihydro-1-Phenyl-Phosphepine / T. Benincori, V. Bonometti, R. Cirilli, R. Ferretti, P. Mussini, M. Pierini, T. Pilati, S. Rizzo, F. Sannicolò, L. Vaghi. ((Intervento presentato al 10. convegno Congresso del Gruppo Interdivisionale di Chimica Organometallica tenutosi a Padova, Italia nel 2012.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/191346
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