• Title/Summary/Keyword: intramolecular cyclization

Search Result 67, Processing Time 0.017 seconds

The Link Between Stereoselectivity and Spin Selectivity in Intermolecular and Intramolecular Photochemical Reactions

  • Griesbeck, Axel G.
    • Journal of Photoscience
    • /
    • v.10 no.1
    • /
    • pp.49-60
    • /
    • 2003

  • How stereo selectivity in singlet and triplet photocycloaddition and photocyclization reactions, respectively, is linked to spin selectivity and how this link affects our understanding of photochemical reaction mechanisms, is described in this review. As illustrative examples, the Paterno-Buchi reaction and the Norrish-Yang cyclization are described with emphasis on triplet biradical structure and dynamics.

  • PDF

A Stereospecific Synthesis of (+)-2-Epideoxymannojirimycin and (2R,3R,4R,5R)-3,4,5-Trihydroxypipecolic Acid

  • 박기훈
    • Bulletin of the Korean Chemical Society
    • /
    • v.16 no.10
    • /
    • pp.985-988
    • /
    • 1995

  • 2-Epideoxymannojirimycin 1 and (2R,3R,4R,5R)-3,4,5-trihydroxypipecolic acid 2 were prepared starting from D-glucosamic acid as a chiral educt. Key transformations were selective removal of the terminal isopropylidene group and intramolecular cyclization by SN2 reaction.

  • https://doi.org/10.5012/bkcs.1995.16.10.985 인용 PDF

Acid and Base Catalyzed Intramolecular Cyclizations of N-Benzoylthiocarbamoyl-acetals

  • Lee, Bong-Yong;Kim, Choong-Sup;Lee, Jong-Wook
    • Archives of Pharmacal Research
    • /
    • v.23 no.2
    • /
    • pp.99-103
    • /
    • 2000

  • Acid and base catalyzed intramolecular cyclizations of N-benzoylthioureidoacetal, contain-ing four functional groups adjacent to thiourea such as benzocarbamoyl, acetal, thioure and amide, were investigated. The condensation reaction of N-benzoyl thiocarbamoylgly-cine amide in the presence of 10% aqueous NaOH provided 1-(2,2-dimethoxy)ethyl-imi- dazolidine-2-thione exclusively. In the presence of pyridine, it was transformed to 2- thiohydantoin. N-Benzoyl thiocarbamoyl glycine amide was completely transformed to an iminothiazolidine exclusively in the presence of Lewis acid such as borontrifluoride ether-ate or trimethylsilyl iodide. 1-(2,2-Dimethoxy)ethyl-imidazolidine-2-thione was transformed to imidazole[2,1-b]thiazole and pyrazino[5,1-a]imidazole in the presence of $BF_3$.$ET_2$O and formic acid, respectively.

  • PDF