Synthesis of Nitrogen-containing Heterocycles Using Nitro Compounds as Building Blocks: Part I: Synthesis of 3-substituted Azepanes. Part II: Synthesis of 1-azoniapropellanes as Phase Transfer Catalysts

Synthesis of Nitrogen-containing Heterocycles Using Nitro Compounds as Building Blocks: Part I: Synthesis of 3-substituted Azepanes. Part II: Synthesis of 1-azoniapropellanes as Phase Transfer Catalysts

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The chemistry of nitroalkenes and nitroalkanes has been explored with regard to synthesis of nitrogen-containing heterocycles, including 3-sustituted azepanes and 1-azoniapropellanes. A general synthesis of 3-sustituted azepanes has been developed using nitroalkenes as building blocks. A novel, vinylogous, conjugate addition reaction of an acylsilane-derived dienol ether to nitroalkenes was discovered. Reaction conditions were optimized for a number of 1IA˜-substituted nitroalkenes. Nitro acylsilanes as the conjugate adducts were obtained in good to moderate yield. Nitro acylsilanes were converted to the corresponding enals through a photoinduced protodesilylation. Saturation of the olefinic portion of the enals and subsequent reductive aminations afforded the 3-sustituted azepanes, which were protected as N-tosylamides. Using this streamlined process, a number of 3-sustituted azepanes were obtained in good yield. Efficient synthesis of chiral, enantiopure 1-azoniapropellanes as phase transfer catalysts has been developed. In the first method, the tandem [4+2]/[3+2] cycloaddition of nitroalkene was applied as the key step, wherein a chiral, enantiopure vinyl ether, a nitroalkene and a vinyl ketone were rapidly assembled. The resulting enantiopure nitroso acetals were then elaborated into 1-azoniapropellanes. Four azoniapropellanes were prepared using this method. Another method was developed using the conjugate addition of nitroalkanes to Michael acceptors as the key strategy. Stereochemical control was achieved by the application of Corey-Itsuno reduction of the nitro diketone intermediate. Starting from nitromethane and 1IA˜-chloropropiophenone, rapid access to 2, 8-diphenyl-1-azoniapropellane and 2, 8, 9-triphenyl-1-azoniapropellane was accomplished .The chemistry of nitroalkenes and nitroalkanes has been explored with regard to synthesis of nitrogen-containing heterocycles, including 3-sustituted azepanes and 1-azoniapropellanes.


Title:Synthesis of Nitrogen-containing Heterocycles Using Nitro Compounds as Building Blocks: Part I: Synthesis of 3-substituted Azepanes. Part II: Synthesis of 1-azoniapropellanes as Phase Transfer Catalysts
Author: Min Xie
Publisher: - 2010
ISBN-13:

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