- Research on unique masked ortho-benzoquinone, monohemiaminal: Synthesis and reactions
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Synthesis of ortho-benzoquinone monohemiaminals via the oxidative dearomatization/O-cyclization cascades of phenols bearing an ortho substituent derived from an amino alcohol with PIDA is described. The cascade reactions of substrates bearing a chiral substituent were found to proceed in a stereoselective manner. The Diels-Alder reactions of the ortho-benzoquinone monohemiaminals proceed in a highly stereoselective manner. The oxidative dearomatization/O-cyclization cascade affording the ortho-benzoquinone monohemiaminal had never been reported; hence, there is still ample scope for further investigation.
- Matsumoto, Yuri,Nakamura, Akihiko,Saito, Emi,Nakada, Masahisa
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p. 232 - 252
(2019/04/27)
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- Binuclear versus mononuclear copper complexes as catalysts for asymmetric cyclopropanation of styrene
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A number of (S)-(-)-2-amino-1,1-diaryl-1-propanol compounds have been synthesized. They were used to form the binuclear copper complexes through a spontaneous assembly of the individual components, the β-aminoalcohol, 2- hydroxy-5-methyl-1,3-benzenedialdehyde, and copper acetate monohydrate, in methanol. These binuclear complexes were examined as asymmetric catalysts for cyclopropanation of styrene by ethyl diazoacetate. Moderate improvement in enantioselectivity has been observed for the binuclear versus mononuclear copper complexes. The e.e. values up to 87% for trans and 93% for cis products and the ratio between trans and cis products up to 9:1 have been obtained.
- Cai, Lisheng,Mahmoud, Hussein,Han, Ying
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p. 411 - 427
(2007/10/03)
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