Stereoselective Construction of Seven-Membered Rings with an All-Carbon Quaternary Center by Direct Tiffeneau-Demjanov-type Ring Expansion
Takuya Hashimoto, Yuki Naganawa and Keiji Maruoka*
*Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan, Email: maruokakuchem.kyoto-u.ac.jp
T. Hashimoto, Y. Naganawa, K. Maruoka, J. Am. Chem. Soc., 2009, 131, 6614-6617.
DOI: 10.1021/ja900941k (free Supporting Information)
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A highly diastereoselective insertion of α-alkyldiazoacetates to cyclohexanone and its heteroanalogues furnishes seven-membered rings with 1,4-quaternary-tertiary, 1,4-quaternary-quaternary, or 1,3,5-quaternary-tertiary-tertiary stereogenic centers in a single operation starting from readily available materials.
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