pplication of the intramolecular azomethine imine cycloaddition to the construction of a novel, orthogonally protected spirodiamino acid scaffold
Dolle RE., Barden MC., Brennan PE., Ahmed G., Tran V., Ho DM.
Hydrazone 4 undergoes tandem intramolecular Michael addition - intramolecular azomethine imine cyctoaddition in ethanol at reflux to furnish the tricyclic pyrazoline methyl ester 3 in 75% yield. A five-step conversion of 3 to N1-Alloc-6-(N-Boc-aminomethyl)-1-azaspiro[4.4]nonane-2-acetic acid 1 provides access to a unique tri-functionalized scaffold for combinatorial chemistry.