Titanium isoproxide

The hydrolysis reaction to obtain zirconium titanate (ZT), ZrTi04, was performed with the alkoxides zirconium n-propoxide (NPZ) (Dupont), and titanium isoproxide (TFT) Dupont, deionized water in the presence of nitric acid (Merck). The solvent used was n-propanol (Merck). 

The cyclopropylamine scaffold is a recurrent moiety in several natural products or drugs [24]. However, its preparation usually requires several steps [25]. Szy-moniak and Bertus have developed an amino version of the Kulinkovich [26] reaction for quicker access to these aminocyclopropanes from nitrile derivatives, Grignard reagents, and titanium isoproxide (Scheme 9.15) [27]. Starting from p- or... 

Another synthetic use of the M-P-V reaction has been exploited in the synthesis of new alkoxide derivatives.247,248 Hence, 2-hydroxybenzaldehyde (salicylaldehyde) will react with isoproxides of titanium and zirconium to initially displace isopropyl alcohol and give mixed derivatives which on heating undergo reduction of the aldehyde function with elimination of acetone. The stoichiometry of the overall reaction can be represented as shown in equation (66).248... 

A flask is cooled to — 20 °C and 1.24 g (6.0 mmol) of ( + )-diethyI L-tartrale and 1.49 mL (1.42 g, 5.0 mmol) of titanium(IV) isoproxide are added sequentially by syringe with stirring. The reaction mixture is stirred at — 20 °C as 39 mL (200 mmol, 5.17 M in isooctanc) of terf-butyl hydroperoxide are added through the addition funnel at a moderate rate (over ca. 5 min). The resulting mixture is stirred at — 20 °C for 30 min. 12.82 g (100 mmol) of freshly distilled ( )-2-octenol, dissolved in 50 mL of CH,C12, are then added drop-wise through the same addition funnel over a period of 20 min, being careful to maintain the reaction temperature between —20° to — 15°C. The mixture is stirred for an additional 3.5 h at —20° to —15 °C. The workup procedure as above with iron(II) sulfate solution yields the epoxy alcohol (12.6 g, 88% crude yield, 92.3% cc by GC) which upon two rccrystallizations from petroleum ether (bp 40- 60°C) at — 20°C gives the product yield 10.5 g (73%) >98% ee. 

The Sharpless epoxidation of allylic alcohols with tert-butylhydroperoxide and titanium(IV) isoproxide has been carried out with a polymeric tartrate made from tartaric acid and 1,8-octanediol.114 The yield of epoxide (92%) was comparable with that when dimethyl tartrate was used (91%), but the 79% ee was lower than the 98% ee found with the dimethyl tartrate. It may be possible to raise the ee by further variations in the structure of the polymer. The heterogenization of a catalyst for a homogeneous reaction often requires optimization to obtain comparable or higher yields and stereospecificity. 

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