[C:1]([C:5]1([CH3:12])[CH2:10][CH2:9][CH:8]=[C:7]([CH3:11])[O:6]1)(OC)=[O:2].[H-].[Al+3].[Li+].[H-].[H-].[H-].O.[OH-].[Na+]>CCOCC>[CH3:12][C:5]12[CH2:1][O:2][C:7]([CH3:11])([O:6]1)[CH2:8][CH2:9][CH2:10]2
A solution of 2-carbomethoxy-2,6-dimethyl-3,4-dihydro-2 H-pyran (11.2 gm, 0.066 mol) in dry ether was added dropwise with stirring to lithium aluminum hydride (3 gm, 0.079 mol) in dry ether. The reaction mixture was heated under reflux for 4 hours, cooled and decomposed with water (3 ml), aqueous 15% NaOH solution (3 ml) and finally water (9 ml). It was stirred at room temperature for 2 hours and filtered. The ether solution containing the resulting alcohol was treated with a catalytic amount of p-toluenesulfonic acid, stirred at room temperature for 2 hours and neutralized with K2CO3. The solvent was removed using a 40 cm Vigreux column and the residue was distilled to give 7.6 gm (75.6%) of frontalin.
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