Telescoped Process

1 Diastereoselectivity of Hydrogenation of rac-tetralone-Methylimine The Old (MeNH2lTiCl4lToluene) Method Is Improved by Using MeNH2lEt0H-Pd/CaC03, 60-65°C in a Telescoped Process 

Traditionally, condensation of 4 with methylamine was promoted by TiCLt in toluene with an excess of methylamine, producing the hazardous by-products, titanium dioxide and methylamine hydrochloride [12]. An extremely simple, innovative approach was recently described that provides conversion of 5-1 and avoids this disadvantage [13]. It relies on the low-solubility of imine 5 in alcohols, driving the reaction equilibrium towards the final product. The reaction is performed in a pressure vessel at 60-65°C providing 95% conversion to 1. 

This inventive step is followed by diastereoselective hydrogenation of 5 to otherwise thermodynamically less stable cis-1 (in the racemic form), using Pd/CaCOa (1% w/w). This improves diastereoselectivity by up to 95% d.e., well above the 80% previously achieved. Moreover, fliis catalyst was found to perform best in alcohols, providing the conditions for development of a telescopedprocess . This process is characterized by 

2 Kinetic Resolution of Racemic Methylamine Hydrosilylation by (R,R)-(EBTHI)TiF2/PhSiH3 Catalytic System 

Activation of the (7 ,f )-(EBTHI)TiF2 complex by PhSiH3 leads, in the first step, to the Li2TiH complex. Initial insertion of the imine in the Ti-H bond is followed by proton-transfer and departure of the chiral intermediate II, followed by formation of the Ti-N bond in V and the chiral product IV. The cycle is completed by the intervention of phenylsilane and regeneration of the L2TiH catalytic species. High enantioselectivity of the hydride transfer is controlled by the steric demand of the chiral ligand in the titanocene complex, in which diastereotopicity of the two sites of the C=N bond assures stereoselection. 

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In summary, we have described a novel and efficient synthesis of thienobenzazepine derivatives in which the key transformation includes a telescoped process involving a selective intro reduction followed by palladium-mediated intramolecular amidation. The process developed is quite amenable for preparative scale (multi-gram) and presents significant advantage to those reported previously with respect to overall yield (e.g., 50% vs. 17% overall yield), total number of synthetic transformations (4 vs. 9), and reagents and/or conditions that are suitable for large-scale synthesis. 

Taber, G. P. Pfisterer, D. M. Colberg, J. C. A New and Simplified Process for Preparing N-[4-(3,4-Dichlorophenyl)-3,4-dihydro-l(2H)-naphthalenyl-idene]methanamine and a Telescoped Process for the Synthesis of (IS-cis)-4-(3,4-Dichlorophenol)-1,2,3,4-tetrahydro-N-methyL 1 -naphthalenamine Mandelate Key Intermediates in the Synthesis of Sertraline Hydrochloride. Org. Proa Res. Dev. 2004, [Pg.431]

Synthesis gas is obtained either from methane reforming or from coal gasification (see Coal conversion processes). Telescoping the methanol carbonylation into an esterification scheme furnishes methyl acetate directly. Thermal decomposition of methyl acetate yields carbon and acetic anhydride,... 

Ammoxidation illustrates several principles. First, it shows the benefit of telescoping two successive processes into one reactor. The Sohio inventor, James D. Idol, Jr., observed that catalysts for two successive stages in an earlier ammoxidation procedure were very similar. He then found that the same catalyst could be used for both, thus eliminating a complete plant stage, at great saving of capital and operating cost ... 

Telescope the Process by Combining Stages. This has been done successfully in the conversion of propylene to acrylonitrile by direct ammoxidation rather than oxidation to acrolein followed by reaction with ammonia in a separate stage, as was described in the earlier patent literature. The oxychlorination of ethylene and HC1 directly to vinyl chloride monomer is another good example of the telescoping of stages to yield an economic process. 

Large-Scale Synthesis of Thienobenzazepine Derivatives Using Two Efficient Metal Catalyzed Processes Telescoped Nitro Reduction and Intramolecular Aminocarbonylation... 

In 1994, a unique incident occurred the impact of the Shoemaker-Levy comet on the Jovian atmosphere. Die strong gravitational field of Jupiter caused the comet to break up before it could enter the atmosphere, and the parts of the comet crashed separately into the atmosphere one after the other. This unique spectacle was observed by many observatories and also by the Galileo spacecraft and the Hubble telescope. It led to the discovery of yet another phenomenon the most intensive aurora effects in the solar system, observed at Jupiter s poles. Astronomers assume that the energy for these comes from the planet s rotation, possibly with a contribution from the solar wind. This process differs from that of the origin of the aurora on Earth, where the phenomenon is caused by interactions between the solar wind and the Earth s magnetic field. 

Studies carried out on Earth, for example, by the NASA infrared telescope on Mauna Kea (Hawaii), showed albedo variations which indicated the presence of holes in the Titanian cloud formations (Griffith, 1993). It is, however, still unclear as to whether these inhomogeneities result from differences in the surface composition. Lorenz et al. (1997) reported large variations in Titan s atmosphere due to photochemical processes. The methane contained in the dense nitrogen atmosphere is decomposed by solar and thermal radiation, and its content may be replenished from methane lakes or from clathrates. 

Recent observations of the HF (1-0) R9 line at 2.3 /tm with the Phoenix spectrograph on the Gemini-South telescope has opened a new window that sheds light on understanding the chemical evolution of fluorine and the nuclear processes that produce this element. Until recently, only a small number of observations of fluorine were available and the trend of fluorine abundances with metallicity had yet to be probed in the Galaxy. 

Orion Constellation This is a mosaic picture of 18 (6x3) frames. Additional four frames are added around the Barnard Loop region to increase S/N. Vignetting of the telescope is corrected by flat fielding, using proprietary software written in IDL. Distortion correction and initial colour match is done in Registar, with final colour correction and mosaic processed using Photoshop. (Reproduced by permission of Wei-Hao Wang, Institute for Astronomy at University of Hawaii)... 

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