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.
- Azomethine imine
- Combinatorial chemistry
- Intramolecular dipolar cycloaddition