[Na].[N+]([CH:5]([C@@H:7]1[C@@H:14]2[C@@H:10]([O:11][C:12](=[O:15])[CH2:13]2)[CH2:9][C@H:8]1[CH3:16])[CH3:6])([O-])=O.[N+](=C)([O-])[O-:18].S(=O)(=O)(O)O>CO.O.C(O)(=O)C>[C:5]([C@@H:7]1[C@@H:14]2[C@@H:10]([O:11][C:12](=[O:15])[CH2:13]2)[CH2:9][C@H:8]1[CH3:16])(=[O:18])[CH3:6]Sodium (1.3 g) was dissolved in methanol (30 mL) and the solution added at 0° to a methanol (40 mL) solution of the crude, optically active (3aR,4S,5R,6aS)-4-(1-nitroethyl)hexahydro-5-methyl-2H-cyclopenta[b]furan-2-one (10.0 g). This nitronate anion solution was added, 30 minutes later and at -30°, to a cold (-30°) solution of concentrated sulfuric acid (6 mL) in methanol (40 mL). The resulting mixture was processed as in Example III, including hydrolysis with acetic acid (8 mL) in water (30 mL) while stripping, to give 8.47 g (99%) of the crude, optically active (3aR,4S,-5R,6aS)-4-acetylhexahydro-5-methyl-2H-cyclopenta[b]furan-2-one as a yellow oil. This material was used directly in Example XIV.
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