A study of the Overman rearrangement of cyclopropenyl 2,2,2-trichloroacetimidates.

摘要

The conversion of cyclopropenes to cyclopropanes and methylenecyclopropanes is an exothermic process due to relief of ring strain, and therefore cyclopropenes can readily be used as precursors to both of these less strained carhocycles. In this context, a novel reaction to prepare nitrogen-substituted benzylidenecyclopropanes (BCPs) from cyclopropenyl 2,2,2-trichloroacetimidates (imidates) has been developed and is discussed in this thesis. A range of cyclopropenylcarbinols were prepared from tribromocyclopropanes and were then treated with DBU and Cl3CCN at -35°C to -78°C to deliver imidates. When p-tolyl-substituted cyclopropenylcarbinol was reacted overnight with DBU and CI3CCN at room temperature, the reaction led to thermal rearrangement to afford resulting 2,2,2-trichloroacetamide (amide) in 91% yield. The catalysis of p-methoxy- and phenyl-substituted imidates with 5 mol% of PdCl2(MeCN)2 provided corresponding amides in 37-56% yields. The treatment of trimethylcyclopropenyl imidate with silica underwent ring-opening to deliver allenes. Further reactivity of BCPs is also discussed. Newly developed BCPs will have a significant contribution in medicinal chemistry, particularly toward the synthesis of antibacterial, anti-HIV, and anti-HBV agents.