(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one
(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one ??
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(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one C??? ??, ??, ??
(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one ?? ?? ? ???
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(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one ?? ??
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(2R)-2-Ethoxy-2,3,5,6-tetrahydro-4H-pyran-4-one ?? ??: