TiCl3, reduction

Urine TDG, TOGO TiCl3 reduction, derivatization Negative ion Cl GC-MS-MS <1 ng/mL Black and Read (1995a)... 

For preparative purposes, titanium metal can be used in place of sodium or lithium in liquid ammonia for both the vinyl phosphate231 and aryl phosphate232 cleavages. The titanium metal is generated in situ from TiCl3 by reduction with potassium metal in tetrahydrofuran. 

Another process that is widely used involves reduction by Zn-Cu couple. This reagent is especially reliable when prepared from TiCl3 purified as a DME complex,243 and is capable of forming normal, medium, and large rings with comparable efficiency. 

Reductive elimination from 2-en-l,4-diol derivatives has been used to generate 1,3-dienes. Low-valent titanium generated from TiCl3-LiAlH4 can be used directly with the diols. This reaction has been used successfully to create extended polyene conjugation.305... 

Electrocatalytic reduction of carbon dioxide to Q-C3 hydrocarbons with less than 0.2% electrochemical yield was reported154 at pH 7 in the presence of pyrocatechol, TiCl3, and Na2Mo04 at -1.55 V versus SCE. 

Pd(0)-catalyzed substitution reaction, a novel, mild reduction of a-nitro ester to an amino acid ester with TiCl3, and an improved procedure for uracil ring formation. 

Reduction of nitrostyrene with aqueous TiCl3 gives a 3,4-diarypyrrole directly in moderate yield (Eq. 10.46).52 The reaction proceeds via dimerization of anion radicals of nitrostyrene and reduction of the nitro function in the dimer to imines. Reduction of dinitrile with diisobutylalu-minum hydride (DIBAL) gives a-free pyrroles (Eq. 10.47) 53 both reactions may proceed in a similar mechanism. These pyrroles are useful intermediates for functionalized porphyrins. 

Similar to the Fisher indole synthesis, reductive cyclization of nitro aromatics offers a powerful means of forming indoles. Reductive cyclization of ortho, 2 -dinitrostyrenes has occurred in many ways, by TiCl3, NaBH4-Pd/C, H2-Pcl/C, and other reductive methods.89 Corey and coworkers have used the Borchardt modification (Fe-AcOFI, sihca gel, toluene at reflux for the reductive cyclization of o-ji-dinitrostyrenes) to prepare 6,7-dimethoxyindole (Eq. 10.65) in a total synthesis of aspidophytine (see Schemes 3.3 and 3.4 in Section 3.2.l).89d... 

The proposed catalytic mechanism for intramolecular McMurry reaction begins with the reduction of TiCl3 by zinc metal to generate the activated titanium species A-19. Reductive cyclization of the dicarbonyl substrate forms the McMurry coupling product, along with titanium oxide complex B-15. To close the catalytic cycle, the oxide complex B-15 is converted to TiCl3 by Me3SiCl (Scheme 63).8d,8e... 

Magnesium chloride has a crystal structure very similar to violet titanium trichloride. This dictates the possibility of an epitaxial coordination of TiCU units (or TiCl3 units, after reduction) on the lateral coordinatively unsatured faces of MgCl2 crystals, giving rise to relieves crystallographically coherent with the matrix.150... 

Reductive elimination of an allylic diol group. A new synthesis of vitamin A involves reduction of the allylic diol 1, prepared in several steps from JJ-ionone, with a low valent titanium formed from TiCl3 and LiAlH, in the ratio 2 1. Thus, the allylic diol group of 1 [either (E) or (Z)] is reduced to an (E,E)-1,3-diene group to form the silyl ether (2) of vitamin A.1 When the primary hydroxyl group is protected as an acetate, the reduction gives a mixture of (E)- and (Z)-2. 

At the same time, McMurry with species of Ti(0) prepared by reduction of TiCl3 with potassium or lithium in liquid ammonia, obtained excellent yields of... 

Aliphatic ketones reductively dimerize upon treatment with TiCl3 (reported as TiCla in the literature (vide supra)) and zinc in the presence of pivalonitrile in dichloromethane (Equation (14)). In the reaction, addition of pivaloni-trile produces a dramatic accelerating effect. 

Vj = ml of -ferric ammonium sulfate soln required to titrate the excess TiCl3 after reduction of DNEcBz N =b normality of the ferric ammonium sulfate soln... 

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