Issue 8, 2001

Synthesis, structure, and interconversion of chiral rhenium oxygen- and sulfur-bound sulfoxide complexes of formula [(η5-C5H5)Re(NO)(PPh3)(OS(Me)R)]+ X; diastereoselective oxidations of coordinated methyl alkyl sulfides

Abstract

Reactions of the chiral chlorobenzene complex [(η5-C5H5)Re(NO)(PPh3)(ClC6H5)]+BF4 (1+ BF4) and alkyl methyl sulfoxides O[double bond, length as m-dash]S(Me)R (R = a, Me; b, Et; c, i-Pr or d, t-Bu), at −15 °C gave the oxygen-bound sulfoxide complexes [(η5-C5H5)Re(NO)(PPh3)(O[double bond, length as m-dash]S(Me)R)]+ BF4 (2a–2d+BF4; 94–56%). Above 0 °C, 2a–2d+BF4 rearrange to sulfur-bound linkage isomers [(η5-C5H5)Re(NO)(PPh3)(S([double bond, length as m-dash]O)(Me)R)]+BF4 (3a3d+BF4; 96–20%). The triflate salts 2c,2d+TfO and 3b,3c+TfO are analogously prepared from (η5-C5H5)Re(NO)(PPh3)(OTf ). Complexes 2b–2d+X and 3b–3d+X can exist as two Re, S configurational diastereomers. Stereochemistry is assigned from reactions of (S )- or (R)-1+BF4 with enantiomerically enriched sulfoxides (R)-bd, and a crystal structure of (SReRS,RReSS)-2d+TfO·0.5CH2Cl2. Relative diastereomer stabilities, and the basis for the divergent kinetic and thermodynamic oxygen/sulfur binding selectivities, are analysed. The alkyl methyl sulfide complexes [(η5-C5H5)Re(NO)(PPh3)(S(Me)R)]+ X and dimethyldioxirane react (acetone, −20 °C) to give 3a–3d+X. Diastereoselectivities (3b–3d+X) are fair to good. However, some overoxidation to Ph3P[double bond, length as m-dash]O occurs, lowering yields.

Graphical abstract: Synthesis, structure, and interconversion of chiral rhenium oxygen- and sulfur-bound sulfoxide complexes of formula [(η5-C5H5)Re(NO)(PPh3)(OS(Me)R)]+ X−; diastereoselective oxidations of coordinated methyl alkyl sulfides [ ]

Supplementary files

Article information

Article type
Paper
Submitted
28 Nov 2000
Accepted
13 Feb 2001
First published
23 Mar 2001

J. Chem. Soc., Dalton Trans., 2001, 1218-1229

Synthesis, structure, and interconversion of chiral rhenium oxygen- and sulfur-bound sulfoxide complexes of formula [(η5-C5H5)Re(NO)(PPh3)(OS(Me)R)]+ X; diastereoselective oxidations of coordinated methyl alkyl sulfides

M. Otto, B. J. Boone, A. M. Arif and J. A. Gladysz, J. Chem. Soc., Dalton Trans., 2001, 1218 DOI: 10.1039/B009533H

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