TALEN

Treatment of the substituted azobenzene (561) with triethyl phosphite gave the triazapen-talene (563). It is likely that the 2-substituted benzotriazole (562) was initially formed which then underwent deoxygenative cyclization to (563) (74CL951). 

Other still more unusual structures were obtained in the reaction of the 3a,6a-diazapen-talenes with DMAD (78CL1Q93). Depending on the substituents on the diazapentalene (641 R = R = H or R = COAr, R = Ar), the rearranged 1 2 adducts (642 E = C02Me) and (643 E = C02Me), respectively, were obtained. 

Eine einfache Methodc zur Herstellung von Methylathern stellt die Reduktion von Ace-talen mit Natrium-cyano-trihydrido-boranat in salzsaurem Methanol dar4. 

Das Wechselwirkungsdiagramm der Abb. 13 konstruiert aus den Orbi-talen a und a der Cx—Ca-Bindung sowie dem in der Geriistebene pla-zierten Orbital des einsamen Elektronenpaares am O-Atom der Car-bonylgruppe die an der a-Spaltung beteiligten Orbitale i, 2 und 63. 

Ade-Omowaye, Talens, P., Angersbach, A., and Knorr, D. 2003. Kinetics of osmotic dehydra-... 

Chiralt, A., Martinez-Navarrete, N., Martinez-Monzo, J., Talens, P., Morata, G., Ayala, A., and Fito, P. 2001b. Changes in mechanical properties throughout osmotic processes Cryoprotectant effect. J. Food Engineer. 49, 129-135. 

Talens, P., Escriche, I., Martinez-Navarrete, N., and Chiralt, A. 2002. Study on the influence of osmotic dehydration and freezing on the volatile profile of strawberries. J. Food Sci. 67, 1648-1653. 

The Lewis acid-promoted [4+ 2]-cycloaddition reaction of the allenic ester 103 having a camphor-derived chiral auxiliary with cydopentadiene provided the adduct with excellent Jt-facial selection, leading to an enantioselective synthesis of (-)-/l-san-talene [92]. 

Solvent extraction has become a common technique for the determination of formation constants, P , of aqneons hydrophilic metal complexes of type MX , particularly in the case when the metal is only available in trace concentrations, as the distribntion can easily be measnred with radioactive techniques (see also section 4.15). The method reqnires the formation of an extractable complex of the metal ion, which, in the simplest and most commonly used case, is an nn-charged lipophilic complex of type MA. The metal-organic complex MA serves as a probe for the concentration of metal ions in the aqueous phase through its equilibrium with the free section 4.8.2. This same principle is used in the design of metal selective electrodes (see Chapter 15). Extractants typically used for this purpose are P-diketones like acetylacetone (HAA) or thenoyltrifluoroacteone (TTA), and weak large organic acids like dinonyl naph-talene sulphonic acid (DNNA). 

Porras-Rodriguez, M. Talens-Alesson, F.I. Removal of 2,4-dichlorophenoxyacetic acid from water from adsorptive micellar flocculation. Environ. Sci. Technol. 1999, 33, 3206. 

Optical spectroscopy has merits in identifying radical cations, particularly when their spectra are known independently. For example, the radiolysis of quadricyclane led to the observation of the known spectrum of norbornadiene radical cation. In another study, irradiation of cyclooctatetraene radical cation caused the color of the sample to change from bright red to royal blue, suggesting the conversion to a different species, the previously identified semibullvalene radical cation. Further irradiation of the latter led to a characteristic banded (vibrationally resolved) spectrum the nature of this spectrum suggested that the rearranged species may be a linear conjugated radical cation and helped in its identification as 1,4-dihydropen-talene radical cation. ... 

Tesson L, Usal C, Menoret S et al (2011) Knockout rats generated by embryo microinjection of TALENs. Nat Biotechnol 29 695-696... 

Sander JD, Cade L, Khayter C et al (2011) Targeted gene disruption in somatic zebrafish cells using engineered TALENs. Nat Biotechnol 29 697-698... 

Poland, A., Talen, D., and Glover, E. (1982). Hunor promotion in mouse epidermis by 2,3,7,8- tetrachloridibenzop-diotin," Nature 300,271. 

Except in one case, 451-452,4,7e where an equilibrium is involved, reactions of this type are irreversible. Table V shows conditions under which one of the five-membered rings is cleaved in various azapen-talenes. 

The work of Taddei et al.230 on imidazol2,1 -6]thiazole 337 and derivatives has interesting implications on the structure of azapen-talenes, and an important aspect of this study is that the molecular geometry used for calculations on 6-phenylimidazo[2,l-6]thiazole 417 was obtained from X-ray structure determinations130b (Section V,A). The reactivity of this system (Scheme 18, Section IV,C,4,b) is better correlated with Tr-electron densities than with total charges, and 7r-bond orders (by the PPP method) show that the thiazole part of the molecule is more localized than the imidazole part (Section VII). Proton chemical shifts, except that of the H2 proton a to sulfur (Section V,G,2), vary linearly with the total charge carried by the ring carbon atoms. 

Calculations have shown that the HOMO in the [3,4-c]-annelated A,B-diheteropen-talenes is closely related to the nonbonding MO, thereby allowing ready reaction with electron-deficient dipolarophiles. In the case of the systems with two discrete ylide moieties as in thieno[3,4-c]pyrrole derivatives, it is not only the nature of the HOMO which directs the mode of addition, but also the thermodynamic stability of the adduct, leading to addition across the thiocarbonyl ylide at elevated temperatures and to the azomethine ylide at low temperatures (Section 3.18.4.2.1) (77T3203). 

Pentalene, 22, is another antiaromatic molecule known to undergo bond-shift equilibrium with a barrier of approximately 4 kcal/mol.182 A second-order perturbation Hiickel treatment100 by Heilbronner and Shaik183 indicated that linking pentalene into bipen-talene, 23, should cause one of the moieties to undergo delocalization or at least lower the barrier for achievement of the local D2h situation. Many antiaromatic species seem to behave in the same manner.184... 

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