Ethylene Glycol → (3'aR,6'aS)-hexahydro-1'H-spiro(1,3-dioxolane-2,2'-pentalen)-5'-one

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Reaction Steps

cis-Tetrahydropentalene-2,5(1H,3H)-dione (5 g, 36 mmol) and ethylene glycol (2.3 g, 36 mmol) were dissolved in toluene. To the resulting solution was added PTSA (684 mg, 3.6 mmol). The reaction mixture was refluxed for 12 h meanwhile the resulting water was removed away. Direct chromatography on silica gel gave 2.0 g (11 mmol, yield: 31%) of the desired product, (3a′R,6a′S)-tetrahydro-1′H-spiro[1,3-dioxolane-2,2′-pentalen]-5′(3H)-one: MS (m/e): 183 (M+1)+.

Provenance & Evidence