With TiCU

Laurino examined a similar method in which methanesulfonanilides were alkylated with bromoacetaldehyde diethyl acetal and then cyclized with TiCU[4J. 1 hese methods presumably involve generation of an electrophilic intermediate from the acetal functionality, followed by an intramolecular Friedel-Crafts reaction. As a consequence, the cyclization is favoured by ER substituents and retarded by EW groups on the benzene ring. 

Benzene (3), AIEta (3.4 g, 30 mmol) m n-heptane (200 mL) was treated with TiCU (1.3 g, 10 mmol) In n-heptane (S mL) under N2 with eftidenl stimng. Acetylene 1 was bubbled through a solution of catalyst (30 mL/min). The temperature of the mixture rase slowly from 22°C to 30°C After 5100 mL of 1 was passed through, the catalyst was removed and 3 was distilled (50%). 

Good results were obtained with (R)-0-acryloylpantolactone (4) in which the dienophile was incorporated with a smaller chiral auxiliary. Some results are reported in Table 4.4, where the cycloadditions catalyzed by Zn(II)-, Fe(II)- and Ti(IV)-K-10 exchanged montmorillonite calcined at 120 °C and 550 °C are compared with those that were not catalyzed and with TiCU- and EtAlCh-catalyzed reactions. Among the metal-clays activated, the Ti(IV)-K-10 was the best catalyst with high conversion and acceptable enantioselectivity obtained after 2 h. 

NaBH4). " P-Ketosulfones are reduced with TiCU—Zn, " TiCl4—or... 

When the reactant is of the form ZCH2Z, aldehydes react much better than ketones and few successful reactions with ketones have been reported. However, it is possible to get good yields of alkene from the condensation of diethyl malonate, CH2(COOEt)2, with ketones, as well as with aldehydes, if the reaction is run with TiCU and pyridine in THF. In reactions with ZCH2Z, the catalyst is most often a secondary amine (piperidine is the most common), though many other catalysts have been used. When the catalyst is pyridine (to which piperidine may or may not be added) the reaction is known as the Doebner modification of the Knoevenagel reaction. Alkoxides are also common catalysts. 

P-Hydroxy ketones can be prepared by treating the silyl ethers (53) of a,p-epoxy alcohols with TiCU- ... 

Silyi enol ethers can be dimerized to symmetrical 1,4-diketones by treatment with Ag20 in DMSO or certain other polar aprotic solvents." The reaction has been performed with R , R = hydrogen or alkyl, though best yields are obtained when r = r = H. In certain cases, unsymmetrical 1,4-diketones have been prepared by using a mixture of two silyi enol ethers. Other reagents that have been used to achieve either symmetrical or cross-coupled products are iodosobenzene-Bp3-Et20," ceric ammonium nitrate," and lead tetraacetate." If R =0R (in which case the substrate is a ketene silyi acetal), dimerization with TiCU leads to a dialkyl succinate (34, r =0R)." ... 

Besides their application in asymmetric alkylation, sultams can also be used as good chiral auxiliaries for asymmetric aldol reactions, and a / -product can be obtained with good selectivity. As can be seen in Scheme 3-14, reaction of the propionates derived from chiral auxiliary R -OH with LICA in THF affords the lithium enolates. Subsequent reaction with TBSC1 furnishes the 0-silyl ketene acetals 31, 33, and 35 with good yields.31 Upon reaction with TiCU complexes of an aldehyde, product /i-hydroxy carboxylates 32, 34, and 36 are obtained with high diastereoselectivity and good yield. Products from direct aldol reaction of the lithium enolate without conversion to the corresponding silyl ethers show no stereoselectivity.32... 

In the patterning experiments, chlorinated poly(styrene) films were baked at 120 C for 15 mins, in a forced air oven, equilibrated for -12 hrs. inside the humidity-controlled glove box, exposed to deep-UV radiation and treated with TiCU under usual conditions. No significant variation in the lithographic parameters was observed by varying the relative humidity in the 30-60% range in the glove box. 

Figure 5. RBS spectra of a m-cresol novolac film treated with TiCU for 2 mins, (dotted line) and then etched for 30 mins, by O2 RIE (solid line).

Figure 6. RBS spectra of a PMMA film treated with TiCU for 2 mins.

Sensitivity data for 193 nm exposures were obtained by imaging 1 mm to 1 cm diameter spots in a 1.2 pm thick poly(styrene) film using a Questek ArF excimer laser. Sensitivity was found to be a function of the fluence. For example, one pulse was sufficient to result in a full thickness image after treatment with TiCU and O2 RIE when the fluence was 6 mJ/cm2/pulse (Figure 10). Considerably more dose (32 mJ/cm2) was required to obtain the same result when the fluence was 1... 

A photooxidative scheme has been developed to pattern sub half-micron images in single layer resist schemes by photochemical generation of hydrophilic sites in hydrophobic polymers such as poly(styrene) and chlorinated poly(styrene) and by selective functionalization of these hydrophilic sites with TiCU followed by O2 RIE development. Sub half-micron features were resolved in 1-2 pm thick chlorinated poly(styrene) films with exposures at 248 nm on a KrF excimer laser stepper. The polymers are much more sensitive to 193 nm (sensitivity 3-32 mJ/cm2) than to 248 nm radiation (sensitivity -200 mJ/cm2) because of then-intense absorption at 193 nm. 

So WW, Kim KJ, Moon SJ (2004) Photo-production of hydrogen over the CdS-Ti02 nano-composite particulate films treated with TiCU. IntJ Hydrogen Energy 29 229-234... 

Fig. 10 Variation in thickness of polystyrene brush with [TiCU] [114]...

Jurczak and Kiegiel reported that additions of allylmagnesium chloride and allyl bromide in the presence of Zn to iV-methyl and W-phenylglyoxyloyl-(2R)-borane-10,2-sultam occurred in a diastereoselective manner. Similarly, the Lewis acid mediated addition of allyltrimethylsilane also gave good diastereoselectivity and in the case with TiCU a change of direction of asymmetric induction was observed <99TL1009>. 

Gansauer, and a titanocene complex, TiCl3(THF)3, is also applicable as disclosed by Nelson and co-workers Catalytic pinacol coupling reactions occur with TiCU and zinc (or aluminum) in the presence of an acylating reagent such as acetic anhydride or acetyl chloride. ... 

Treatment of benzaldehyde with TiCU (lequiv.) and magnesium (l.Sequiv.) in TFIE at 25°C for 30min gives a mixture of 1,2-diphenylethene (43% yield) and dl- and OT ro-l,2-diphenylethane-l,2-diols (29% combined yields, dljmeso = AZiS ). The reaction conducted at 80°C produces the diphenylethene in 62% yield selectively. However, when catechol (1 equiv.) is added to the reaction mixture, pinacols are produced selectively in 76% yield dljmeso = 54/46) even at 80 °C. " Ultrasonic irradiation of a mixture of TiCU (15% in dilute HCl solution, 2 equiv.) and magnesium (4 equiv.) in EtOH accelerates the pincaol formation, but the diastereomeric ratio remains at a low level (dljmeso = 68/32). ... 

Pinacol coupling reactions of aromatic aldehydes with commercially available TiCU /> a mixed solvent of THE and dichloromethane show high 47-selectivities." Also, high 47-selectivities are observed with TiCU-BuUTe in DME and TiCU-Bu"Li in Et20 at -50 °C. (see Table 1). 

In a similar type of process, imines have been dimerized to give 1,2-diamines, by a number of procedures, including treatment with AI-PbBr2,693 with TiCU-Mg,694 with SmU,695... 

Diastereoselective reaction of allylsilanes with o-amino aldehydes. The dia-stereoselectivity of the reaction of allylsilane with the protected a-amino aldehyde 1 depends on the quantity of TiCl4 used. Thus anti-selectivity predominates when 1 equiv. of TiCU is used, but syn-selectivity obtains with less than 1 equiv. The a-amino aldehyde 3 shows syn-selectivity with stoichiometric or catalytic amounts of TiCU. These results suggest that aldehydes such as 1 can form both 1 1 and 2 1 complexes with TiCU-... 

The relative importance of the chain transfer process depends on the polymerisation conditions and on the kind of catalyst used. For the MgC /TiCU AIR3 catalyst, over a large range of activator and monomer concentrations, chain transfer with the monomer [scheme (36)] is by far the most important chain transfer reaction. Other chain transfer reactions, particularly the spontaneous transfer, become detectable only under extreme conditions [241,248]. With TiCU—ZnR2 catalysts, chain transfer with the activator appeared to be the most significant chain transfer reaction [249]. 

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