C-H activation: a complementary tool in the total synthesis of complex natural products

David Y-K Chen1, So Won Youn

  • 1Department of Chemistry, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 151-742, South Korea. davidchen@snu.ac.kr

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The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
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