Synthesis 1996; 1996(11): 1380-1388
DOI: 10.1055/s-1996-4392
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Synthesis of Dimethyleneketene Acetals and Their [2+2] Cycloaddition to Olefins and [60]Fullerene as Cyclopropanecarboxylate Synthons

Shigeru Yamago, Atsuo Takeichi, Eiichi Nakamura*
  • *Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan, Fax +81(3)58006889; E-mail nakamura@chem.s.u-tokyo.ac.jp
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Publication History

Publication Date:
31 December 2000 (online)

The synthesis and synthetic utilization of the dimethyleneketene acetal 3 are described in this report. Thermal rearrangement of the methylenecyclopropanone acetal 1 at 150°C gives the dimethyleneketene acetal 3, which serves as a reactive surrogate of the enolate of alkyl cyclopropanecarboxylate, which has thus far been difficult to prepare. The ketene acetal 3 not only gives the corresponding alkyl cyclopropanecarboxylate 4 upon hydrolysis but also undergoes smooth [2+2] cycloaddition to electron-deficient olefins including C60. The cycloadduct undergoes facile ring cleavage upon aqueous workup to give the Michael addition product 6 in high yield. While the cycloadduct 8 due to the reaction between 3 and C60 is thermally unstable to generate C60 upon thermolysis, it undergoes quantitative hydrolytic cleavage to give the ester 10 upon attempted hydrolysis of the acetal moiety under acidic conditions. The cycloaddition of 3 with dialkyl azodicarboxylate also proceeds smoothly to afford cyclopropyl amino acid derivative in excellent yield.

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