TETRAHYDROFURANS: II. SPIRO COMPOUNDS CONTAINING THE TETRAHYDROFURAN RING

Abstract

2-Allyl-2-methallyl-1,3-propanediol (IV) and 2,2-dimethallyl-1,3-propanediol (V) were cyclized in the presence of mineral acid to give 3,3,8-trimethyl-2,7-dioxaspiro(4.4)nonane (VIII) and 3,3,8,8-tetramethyl-2,7-dioxaspiro(4.4)nonane (IX), respectively. Similarly, 2-methallyl-2-(3-methyl-2-butenyl)-1,3-propanediol (VI) afforded 3,3,8,8-tetramethyl-2,7-dioxaspiro(4.5)decane (X). The diol VI was derived from diethyl methallylmalonate by condensation with 3-methyl-2-butenyl bromide, followed by reduction of diethyl methallyl(3-methyl-2-butenyl)malonate (III) with lithium aluminum hydride. The assigned structures of the spiro compounds were supported by infrared and nuclear magnetic resonance spectral analyses.