72930-73-5Relevant academic research and scientific papers
Reductive coupling of carbonyl compounds promoted by cobalt or titanium nanoparticles
Nador, Fabiana,Mascaro, Evangelina,Castro, Melisa,Vitale, Cristian,Radivoy, Gabriel
, p. 312 - 326 (2011/06/17)
The reaction of a series of aldehydes and ketones with readily prepared cobalt or titanium nanoparticles, under mild reaction conditions, led to the obtention of different reductive dimerization products depending on the nature of the transition metal used. Cobalt nanoparticles (CoNPs) allowed the selective transformation of the starting carbonyl compounds into vicinal diols, whereas the reaction promoted by titanium nanoparticles (TiNPs) led to the formation of the corresponding alkenes. In this last case, the use of trimethylsilyl chloride (TMSCl) as additive, at 0 °C, also allowed the obtention of vicinal diols after acidic aqueous work-up. ARKAT-USA, Inc.
Geometric requirements in the ferriin oxidation of benzylic 1,2-diols
Penn, John H.,Plants, Robert C.,Liu, An
, p. 2359 - 2360 (2007/10/03)
The rates of ferriin [i.e. tris(1,10-phenanthroline)iron(III)] oxidation of cis- and trans-1,2-diphenylcyclohexane-1,2-diol have been found to be dramatically different; cis-1,2-diphenylcyclohexane-1,2-diol reacts a minimum of 104 times faster than the corresponding trans-isomer; implications for the oxidation of benzylic diols by ferriin are discussed.
Oxidative Cleavage of vic-Diols Using Copper(II) Bromide-Lithium t-Butoxide: A New Route to Unsymmetrical 1,5- and 1,6-Diketones
Fujiwara, Tooru,Tsuruta, Yumiko,Arizono, Ko-Ichi,Takeda, Takeshi
, p. 962 - 964 (2007/10/03)
Unsymmetrical 1,6-diketones were obtained by the copper(II) bromide-lithium t-butoxide oxidation of 1,2-disubstituted 1,2-cyclohexanediols. The diols were easily prepared by the addition of Grignard reagents to 2-trimethylsiloxy-2-cyelohexenone followed by the hydrolysis and treatment of the resulting 2-hydroxycyclohexanones with the second Grignard reagents. Similarly, 1,5-Diketones were obtained using 2-trimethylsiloxy-2-cyclopentenone as a starting material.
Carbonyl coupling reactions catalytic in titanium and the use of commercial titanium powder for organic synthesis
Fürstner, Alois,Hupperts, Achim
, p. 4468 - 4475 (2007/10/02)
The high thermodynamic stability of titanium oxides formed as the inorganic byproducts in McMurry-type reactions has so far prevented the development of a catalytic procedure for such reductive carbonyl coupling processes. Similarly, a tightly bound oxide layer passivates the surface of commercial titanium, which is unreactive toward organic substrates under conventional conditions. This paper outlines a way to overcome both of these problems. Thus, oxoamides 1a-h can be reductively cyclized to indoles 2a-h using only catalytic amounts of low-valent titanium if the reaction is carried out in the presence of a chlorosilane. Specifically, the method is based upon the in situ generation of an activated titanium species from TiCl3 and Zn in the presence of the substrate, followed by regeneration of titanium chloride from the titanium oxides formed via ligand exchange with the admixed chlorosilane. Its proper choice is crucial for obtaining both good turnover numbers and clean conversions. Depending on the product structure, (TMS)Cl, ClMe2SiCH2CH2SiMe2Cl (5), or ClMe2Si(CH2)3CN (6) was found to be best suited. Similarly, chlorosilanes also effect the activation of commercial titanium powder which may then be used as a performant off-the-shelf reagent for various types of carbonyl and acetal coupling reactions, for the deoxygenation of epoxides and for the reductive cyclization of oxoamides or oxoesters to indoles, benzofurans, and 2-quinolones. Under these conditions retinal can be reductively dimerized to β-carotene in good yield. Moreover, the titanium/ chlorosilane reagent combination exhibits a strong template effect, allowing macrocyclization reactions without recourse to high dilution. Up to 36-membered rings have been closed in that way. 29Si NMR studies provide some insight into the elementary steps responsible for the degradation of the surface oxide layer on titanium by the chlorosilane. The effect of Lewis acid additives on the course of the coupling processes is discussed.
Synthesis and Enantiomer Recognition of Crown Ethers containing Cyclohexane-1,2-diol Derivatives as the Chiral Centre and Enzymatic Resolution of the Chiral Subunits
Naemura, Koichiro,Miyabe, Hajime,Shingai, Yasuhiro
, p. 957 - 959 (2007/10/02)
The cyclohexane-1,2-diol derivatives 1 and 4 of high optical purity have been prepared by enantioselective hydrolysis of their acetates (+/-)-2 and (+/-)-5 using pig liver esterase.The enantiomer recognition behaviour of the chiral crown ethers 11, 14, 15
