The synthesis and chemistry of 1,3-bridged polycyclic cyclopropenes: 8-oxatricyclo[3.2.1.0(2,4)]octa-2,6-dienes

摘要

Three 1,3-bridged polycyclic cyclopropenes, exo-8-oxatricyclo[3.2.1.0(2,4)] octa-2,6-diene (10), endo-8-oxatricyclo[3.2.1.0(2,4)] octa-2,6-diene (11), and exo-6,7-benzo-1,5-diphenyl-8-oxatricyclo[3.2.1.0(2,4)] octa-2,6-diene (12), have been synthesized by elimination of 2-chloro-3-trimethylsilyl-8-oxatricyclo[3.2.1.0(2,4)]-oct-6-enes, 17, 18 and 30, which were generated from 1-chloro-3-trimethylsilylcyclopropene with furan and diphenylisobenzofuran. We have demonstrated a facile route to synthesize the highly strained 1,3-fused polycyclic cyclopropenes, 10, 11, and 12. The stereochemistry of the Diels-Alder reactions of cyclopropene 16 with furan and DPIBF are different. Cyclopropene 16 was treated with furan to form exo-exo and endo-exo adducts (5:2) and treated with DPlBF to generate an exo-exo adduct. Compounds 10, 11 and 12 undergo isomerization reactions to form benzaldehyde and phenyl 4-phenyl-[1]naphthyl ketone to release strain energies via diradical mechanisms.