• Title/Summary/Keyword: Regioselective

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Rhodium-Catalyzed Highly Regioselective C-H Arylation of Imidazo[1,2-a]pyridines with Aryl Halides and Triflates

  • Liu, Yi;He, Lin;Yin, Guoqiang;Wu, Guojie;Cui, Yingde
    • Bulletin of the Korean Chemical Society
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    • v.34 no.8
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    • pp.2340-2342
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    • 2013
  • A convenient Rh-catalyzed C-H arylation of imidazo[1,2-a]pyridines with a variety of aryl halides or triflates has been reported. This process afforded a range of biaryl compounds in excellent yields and showed high activity and broad scope.

A facile synthesis of 4-cyano-3,5-difluorophenol (4-cyano-3,5-difluorophenol의 새로운 합성법)

  • Song, Jeong-Sup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.6
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    • pp.1308-1312
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    • 2006
  • 4-Cyano-3,5-difluorophenol, useful as intermediate in the manufacturing of liquid crystals, was prepared by the regioselective iodination of 3,5-difluorophenol to give 4-iodo-3,5-difluorophenol, which was then converted to 4-cyano-3,5-difluorophenol under a mild reaction condition. The reaction products were characterized by spectroscopic methods and confirmed by comparison of these analytical data with reported values in the literatures.

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Rhodium(I) Complexes of 1,1$^\prime$-Bis(diphenylphosphino)-ferrocene as Efficient Catalysts in Regioselective Hydrogenation of Polynuclear Heteroaromatic Compounds

  • Kim, Tae-Jeong;Lee, Kyu-Chul
    • Bulletin of the Korean Chemical Society
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    • v.10 no.3
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    • pp.279-282
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    • 1989
  • Two rhodium(I) complexes of the types [Rh(BPPF)(NBD)]$ClO_4$ (10) and [Rh(BPPF)$Cl]_2$ (11) (BPPF = 1,1'-bis(diphenylphosphino)-ferrocene) have been prepared and investigated as catalysts for the regioselective hydrogenation of polynuclear heteroaromatic nitrogen and sulfur compounds such as quinoline (1), acridine (2), phenanthridine (3), 7,8-benzoquinoline (4), benzothiophene (5), isoquinoline (6), indole (7), pyridine (8), and thiophene (9). Both complexes 10 and 11, except for the cases of indole (7) and mononuclear heteroaromatics 8-9, are very efficient in the selective reduction under quite mild hydrogenation conditions to give the corresponding saturated nitrogen and sulfur heterocyclic analogues of 1-6 in fast conversion rates and in excellent yields. Relative rate studies revealed that the reduction depends significantly on the steric and electronic effects of the substrates. Of the two complexes 10-11, the dimeric species 11 gives faster reaction rates in all cases studied.

HANTZSCH DIHYDROPYRIDINE: AN EFFECTIVE AND CONVENIENT REGIOSELECTIVE REDUCING AGENT FOR 5-BENZYLIDENE-2,4- THIAZOLIDINEDIONE DERIVATIVES

  • Lee, Hong-Woo;Kim, Bok-Young;Ahn, Joong-Bok;Son, Hoe-Joo;Lee, Jae-Wook;Ahn, Soon-Kil;Hong, Chung-Il
    • Proceedings of the PSK Conference
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    • 2003.04a
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    • pp.252.3-252.3
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    • 2003
  • An effective and convenient regioselective reduction of 5-benzylidene 2,4-thiazolidinedione derivatives to the corresponding 5-benzyl 2,4-thiazolidinedione derivatives has been accomplished using 3,5-dicarboethoxy-2,6-dimethyl-1,4-dihydropyridine (Hantzsch dihydropyridine ester: HEH) with silica gel as an acid catalyst in a good yield.

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Formal Synthesis of Sex Pheromone of Gypsy Moth (+)-Disparlure from L-(+)-Tartaric Acid

  • Gi Baek Gwon;Hang Soo Kim;Jae Won Park;Jong Soo Choi;Kyung Oh Doh;Kyung Jin Kim;Young Bae, Seu
    • Journal of the Korean Chemical Society
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    • v.68 no.3
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    • pp.131-134
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    • 2024
  • A simple strategy for the formal synthesis of the sex pheromone of gypsy moth (+)-disparlure from L-(+)-tartaric acid is described herein. The key steps include the mono-esterification and regioselective ring-opening of an epoxide using a Grignard reagent. The strategy of conferring asymmetry using 2-butanone enables mono-esterification in high yield and reduces the number of steps. Subsequently, (+)-disparlure is synthesized via the regioselective ring opening of the epoxide.