139416-07-2Relevant articles and documents
Complexes useful as active components in supported epoxidation catalysts
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Page/Page column 25, (2017/04/07)
Method of preparing epoxidation catalysts are disclosed, including methods comprising reacting an inorganic siliceous solid with a metal complex of the formulas: wherein the variables are defined herein.
Titanium aryloxide catalyzed cross-coupling and oligomerization reactions involving 1,3-cyclohexadiene, 1,3-cyclooctadiene, and α-olefins
Waratuke, Steven A.,Thorn, Matthew G.,Fanwick, Phillip E.,Rothwell, Arlene P.,Rothwell, Ian P.
, p. 9111 - 9119 (2007/10/03)
The dimerization/oligomerization and cross coupling of 1,3-cyclohexadiene (1,3-CHD) with α-olefins can be achieved using a variety of titanium aryloxide catalysts. The titanabicyclic compound [Ti(OC6H3Ph4-2,3,5,6)2{CH 2(C6H10)CH2}] initiates the rapid, non-Diels-Alder catalytic dimerization of 1,3-CHD to produce exclusively threo-5-(3-cyclohexenyl)-1,3-cyclohexadiene. Following dimerization of the majority of 1,3-cyclohexadiene into 8, the titanium catalyst then isomerizes (1,5-shift) 8 into 1-(3-cyclohexenyl)-1,3-cyclohexadiene 9 and eventually into a 70/30 mixture (GC analysis) of 9 and 2-(3-cyclohexenyl)-1,3-cyclohexadiene 10. Further cross coupling of dimers 8-10 with themselves and 1,3-CHD leads to trimers (C18 species) and tetramers (C24). This reaction can also be catalyzed by the dichlorides [Ti(OAr)2Cl2] (OAr = 2,6-diphenyl-, 2,3,5,6-tetraphenyl-, 2,6-diphenyl-3,5-dimethyl-, and 2,6-di-isopropyl-phenoxide) and [Cp-(OAr)TiCl2] (OAr = 2,6-diphenyl-3,5-dimethyl-phenoxide) activated with 2 equiv of n-butyllithium (BunLi). In the case of the catalyst system [Ti(OAr)4] or [Ti(OAr)2Cl2] (OAr = 2,6-dimethylphenoxide), activation with 2 equiv of BunLi leads to isomeric mixtures of trimers and tetramers of 1,3-CHD with detectable amounts of pentamers following dimerization. The dimerization product is argued to originate via initial coupling of 1,3-CHD at the Ti metal center to produce 9-titana-octahydrofluorenes. A 1,3-metal shift followed by β-hydrogen abstraction/elimination accounts for the observed regio- and stereochemistry. When the α-olefin Me3SiCH= CH2 is added to 1,3-CHD, these titanium systems generate the cross-coupled product 5-(β-trimethylsilylethyl)-cyclohexa-1,3-diene followed by the formation of trans-5,6-bis(β-trimethylsilylethyl)-cyclohexa-1,3-diene. A mechanism involving initial coupling of the 1,3-CHD and Me3SiCH=CH2 at titanium prior to a 1,3-metal shift and β-hydrogen abstraction/elimination from the initial cyclohexadiene ring is invoked. In contrast cross-coupling of cycloocta-1,3-diene (1,3-COT) with α-olefins RCH=CH2 (R = Ph, Bun, SiMe3) leads to trans-3-(β-alkylvinyl)-cyclooctenes. In this case the reaction is proposed to proceed via similar titanacycles with β-hydrogen abstraction taking place from the alkyl tether instead of the cyclooctene ring.
Synthesis and characterization of alkoxo- and chloro-aryloxo derivatives of titanium and zirconium
Shah, A.,Singh, A.,Mehrotra, R. C.
, p. 632 - 635 (2007/10/02)
The reactions of MX4 (M=Ti, Zr; X=Cl, OPr-i) with a number of sterically demanding phenols, have resulted in the synthesis of novel alkoxo- and chloro-aryloxides of the type MX4-n(OAr)n (where X=Cl, OPr-i; OAr=OC6H2Me3-2, 4, 6(OAr1), OC6H3Pr2-i-2, 6-(OAr2), OC6H2Bu2-t-2, 6-Me-4(OAr3); n=1, 2, 3 or 4).These complexes have been characterized on the basis of IR and NMR spectral studies.
