Synthesis and trapping of spiro [bicyclo[4.2.0]octa-2,3-diene-7,2'-[1,3]dioxolane]

Abstract

Spiro[bicyclo[3.2.0]hept-2-ene-6,2'-[1,3]dioxolane] was synthesized by the reaction of bicyclo[3.2.0]hept-2-en-6-one with ethylene glycol in yield of 92%. Addition of dichlorocarbene to Spiro[bicyclo[3.2.0]hept-2-ene-6,2'-[1,3]dioxolane] gave the 3',3'-Dichlorospiro[1,3-dioxolane-2,7'-tricyclo[4.2.0.02,4]octane] in 50 % yields. Finally, the 3',3'-Dichlorospiro[1,3-dioxolane-2,7'-tricyclo[4.2.0.02,4]octane] was submitted to Doering-Moore-Skatebol reaction for the synthesis of allene precursors. The reaction of the 3',3'-Dichlorospiro[1,3-dioxolane-2,7'-tricyclo[4.2.0.02,4] octane] with methyl lithium (MeLi) in the presence of 1,3-diphenylisobenzofuran (DBI) as a trapping reagent under a nitrogen atmosphere at ca. 0 ℃ was started and continued at room temperature for four hours, resulting in the formation of four cyclo adduct isomers of spiro[bicyclo[4.2.0]octa-2,3-diene-7,2'-[1,3]dioxolane].