Organorhenium compounds

In order to circumvent this problem, there has been significant activity directed toward the search for a less environmentally toxic and more selective oxidizing agent than chromium. For example, Hoechst has patented a process which uses organorhenium compounds. At a 75% conversion, a mixture of 86% of 2-methyl-l,4-naphthoquinone and 14% 6-methyl-l,4-naphthoquinone was obtained (60). Ceric sulfate (61) and electrochemistry (62,63) have also been used. 

Staff RE Rhemum Organorhenium Compounds Bimclear Compounds, Springer-Verlag, Inc., New York, NY, 1996,... 

W. A. Herrmann, M. Dieter, W. Wagner, J. G. Kuchler, G. Weichselbaumer, R. Fischer, Use of organorhenium compounds for the oxidation of multiple C-C bonds, oxidation based thereon and novel organorhenium compounds, US Patent 5,155,247, Oct. 13, 1992, To Hoechst Aktiegesellschaft. 

We have directed our interest towards some unprecedented organorhenium compounds that display the metal in high or intermediate oxidation states. The present chapter is an evaluation of the present state of this subject and a perspective on the exciting new field of "organometallic oxides". 

Asymmetric epoxidations of alkenes catalysed by chiral monomeric organorhenium (VII) and organomolybdenum(VI) compounds,160 ketones,161 and salen-metal complexes162 have been reviewed. The advances in the catalysed Baeyer-Villiger oxidation... 

The simple organorhenium(VII) compound methyltrioxorhenium (Structure 1 in Scheme 1) - called MTO - has developed a plethora of applications in catalytic processes [1], This rapid development occurred in the decade of 1990-2000. The epoxidation of olefins (cf. Section 2.4.3) became attractive to industrial applications. There is sound evidence that MTO represents the most efficient catalyst for this process, being active even for highly dilute solutions of hydrogen peroxide. The latter oxidant is not decomposed by MTO, as opposed to many other metal complexes (cf. Section 3.3.13.1). 

F. E. Kiihn, J. Zhao, W. A. Herrmann, Chiral monomeric organorhenium(Vll) and organomo-lybdenum(VI) compounds as catalysts for chiral olefin epoxidation reactions. Tetrahedron Asvmm. 16 (2005) 3469. 

Even by 1989, the importance of rhenium compounds in oxidation catalysis was still minimal [1], This picture has changed dramatically since organorhenium(VII) oxides, especially the water-soluble methyltrioxorhenium (MTO, 1), have proven to be excellent catalyst precursors for a surprisingly broad variety of processes, most notably for a variety of oxidation reactions [2, 3]. This article summarizes the behavior of MTO and its peroxo derivatives in the presence of water and under catalytic condition in aqueous systems, particular attention being given to the most recent findings. 

Today, there is a whole range of organorhenium oxides available, and these can be considered as one of the best examined classes of organometallic compounds [63,64]. From a catalytic point of view, though, MTO is one of few organorhenium oxides that... 

---