Synthesis of Organotitanium Complexes from Alkenes and Alkynes and Their Synthetic Applications

Mechanistic aspects of chemo- and regioselectivity in Cp2ZrCl2-catalyzed alkene cycloalumination by AlEt3

“…First, if "Cp 2 Zr II " is generated under the reaction conditions, why the same minor by-products are not observed in the case of linear alkenes? Second, unlike "Cp 2 Ti II " [42], "Cp 2 Zr II " was not experimentally identified, and it's involvement in the alkene (alkyne) transformation processes is being questioned [14], [43]. Third, according to our calculation the probability of "Cp 2 Zr II " formation at room temperature is low due to the high value of the Gibbs free energy for the dissociation 10 → "Cp 2 Zr II "+C 2 H 4 (30.4 kcal/mol).…”

Synthesis and Structure-Property Relationships of Phosphole-Based π Systems and Their Applications in Organic Solar Cells

“…An additional useful result obtained in this project was the establishment of a convenient method for the synthesis of 1 from readily available substrates and reagents in a few steps (Scheme 3). [12] Treatment of diethyl nona-2,7-diynedioate with Sato and Urabe's titanium(II) reagent, generated in situ from Ti(OiPr)4 and two equivalents of iPrMgCl, [13] produced the titanacyclopentadiene (titanacycle) intermediate 2, which then underwent metathesis with dichloro(phenyl)phosphine to give the target phosphole 1 in 50% isolated yield. A practical advantage of this method is its functional group tolerance; i.e., ester groups are compatible under the reaction conditions used.…”

Synthetic Reactions Using Low-valent Titanium Reagents Derived from Ti(OR)4or CpTiX3(X = O-i-Pr or Cl) in the Presence of Me3SiCl and Mg

“…The author and others have found that the reduction of inexpensive, readily available Ti(IV) alkoxides (or chloro alkoxytitanium compounds) with two equivalents of an alkyl Grignard reagent or n-BuLi can generate divalent titanium equivalents (h 2 -alkene)Ti(OR) 2 , and various synthetic applications of these reagents have been reported (Scheme 3). [6,7] Note that (h 2 -alkene)Ti(OR) 2 complexes are equivalents of the corresponding titanacyclopropane compounds and act as a dianion species, reacting with esters to provide cyclopropanols (Kulinkovich reaction) (Scheme 3). [7] In the generation of the divalent titanium reagent (h 2 -propene)Ti(O-i-Pr) 2 from Ti(O-i-Pr) 4 or ClTi(O-i-Pr) 3 and 2 i-PrMgCl, i-PrMgCl acts as both a selective reducing agent and a ligand source (propene) to stabilize metastable Ti(II).…”