Preparation of 2-(3-Bromo-1-methylpropyl)-1,3-dioxolan and the Corresponding Chloride From 2-Methylbutyrolactone

Lithium aluminium hydride reduction of ethyl 4-chloro-2-methylbutanoate (4a), derived from 3-methyldihydrofuran-2(3H)-one (2-methylbutyrolactone) (1), gave 4-chloro-2-methylbutan-1-ol (5a), oxidation of which with pyridinium chlorochromate afforded 4-chloro-2-methylbutanal (8a). The aldehyde (8a) was converted into 2-(3&38242;-chloro-1'-methylpropyl)-1,3-dioxolan (7a) in 47% overall yield from (1). 2-(3'-Bromo-1'-methyIpropyl)-1,3-dioxolan (7b) was similarly obtained in 49% overall yield from (1). Attempted conversion of 3-methyltetrahydrofuran-2-ol (2) into the corresponding cyclic ethylene acetal gave epimeric mixtures of 2-(3'-methyltetrahydrofuran-2'-yloxy)ethanol (6) and 2,2'-ethylenedioxybis(3-methyltetrahydrofuran) (9).