Lewis Acid Promoter Reaction of Pentacyclo(5.4.0.0(2,6).0(3,10).0(5,9))undecane-8,11-dione with Ethyl Diazoacetate: A Synthetic Entry into the Pentacyclo(6.5.0.0(4,12).0(5,10).0(9,13)tridecane Ring System

摘要

Reaction of pentacyclo(5.4.0.(2),(6).0(3),(10).0(5,9)undecane-8,11-dione with ethyl diazoacetate (2 equivalents) in the presence of boron trifluoride etherate affords a single 2:1 adduct, diethyl pentacyclo-(6.5.0.0(4,12).0(5,10).0(9,13)tridecane-3.6-dione-2-7- dicarboe (3a, 45% yield). The structure of 3a was established via single crystal X ray structural analysis. When 3a was refluxed with aqueous sulfuric acid or heated with sodium chloride in dimethylsulfoxide, hexacyclo(6.5.0.0(3,7).0(5,10).0(9,13)-tridecane--one (4) was produced in 70% and 97% yield, respectively. Reaction of 4 with phosphorus pentachloride afforded diethyl 3,6-dichloropentacyclo(6.5.0.0(4,12).0(5,10).0(9,12)tridecane-2.6-diene- 2.7-dicate (5, 36%). Compound 5 could not be photocyclized to the corresponding homohexaprisamne, 6.