Triaryl -olefin

J.E. Lynch and co-workers reported the asymmetric total synthesis of the PDE IV inhibitor CDP840 in which they utilized the Jacobsen epoxidation to introduce the only stereocenter of the target. The triaryl (Z)-olefin substrate was epoxidized with significantly higher enantiomeric excess than the triaryl ( )-olefin. This finding was interpreted with Jacobsen s skewed side-on approach model. 

Using Jacobsen et al. s conditions, scientists at Merck developed an enantioselective approach to CDP840, a selective inhibitor of phosphodiesterase (PDE) IV (Scheme 35.13). Jacobsen epoxidation of triaryl olefin 48 using 37 as catalyst and 4-(3-phenylpropyl)pyridine iV-oxide (PPPNO) as an additive gave a single epoxide isomer 49 in 58% yield and 89% ee. The absolute stereochemistry was controlled by the skewed side-on approach... 

Shell Chemical has a process that does both the Oxo reaction and hydroformyiation in one step in the same reactor. They use a special catalyst, thought to be cobalt modified with a trialkyl or triaryl phosphine ligand— but they are holding this one pretty close to the vest. Overall yields are 70-80%, with straight-chain alcohols representing greater than 80%. Major by-products are paraffins that are recovered and used to make olefins and then recycled back as feed. This process can also use internal olefins (with the double-bond somewhere besides the alpha position) and yield similar normakiso alcohol ratios. ... 

Uddin MJ, Rao PNP, Knaus EE (2004) Design and synthesis of acyclic triaryl (Z)-olefins a novel class of cyclooxygenase-2 (COX-2) inhibitors. Bioorg Med Chem 12 5929-5940... 

Chromic acid oxidation of olefins can rarely be used for the preparation of oxiranes because they occur as intermediates that rapidly undergo further transformation. From an investigation of the mechanism of oxidation of triaryl-substituted olefins, it was concluded that a carbonium ion or cyclic chromate ester is a possible intermediate. Selective epoxidation of compounds containing conjugated double bonds is attainable by means of chromic-acid oxidation (Eq. 48) 535 Exclusively cis product was obtained from a highly substituted octalin with Na2Cr04, KMn04, or ozone (Eq. 49). ... 

Nucleophilic Attack on Carbon.—Activated Olefins. Triaryl-... 

Chlorinated alpha-olefin, liquid Chlorinated n-paraffins (C6-C18) Chloro-n-paraffin (C8-22) Isodecyl diphenyl phosphate Octyl stearate PEG-8 ditallate PEG-12 ditallate Sorbitan dioleate Triaryl phosphate EP agent, aerospace Chlorotrifluoroethylene polymer Perfluoropolyether EP agent, agric. 

Kakusawa, N., Tsuchiya, X, and Kurita, J., Photochemically induced coupling reaction of triaryl-stibines with olefins. Tetrahedron Lett., 39, 9743, 1998. 

When the reaction was promoted by the unmodified catalysts [(cod) Rh(hfacac)] (hfacac = hexafluoroacetylacetonate CF3COCHCOCF3, cod = cyclooctadiene), the superiority of SCCO2 in the hydroformylation rates was demonstrated very well. The modified catalytic systems formed with perfluoroalkyl-substituted triarylphos-phine and triaryl phosphite ligands exhibited higher regioselectivities in scCOj than in conventional solvents. The olefin isomerization is a typical side reaction for phosphite-modified systems in conventional solvents, while it is suppressed effectively in SCCO2. 

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