Synthesis of Six-Membered <i>N</i>-Heterocyclic Carbene Precursors Based on Camphor

Abstract

The endo- and exo-N-heterocyclic carbene precursors based on camphor were prepared diastereoselectively in five synthetic steps starting from (1S)-(+)-ketopinic acid. The obtained N-heterocyclic carbene precursors were investigated in an asymmetric benzoin reaction. All new compounds were fully characterized, and the absolute configurations were determined via X-ray diffraction and NOESY measurements.

Keywords

• ketopinic acid
• amidation
• reduction
• diamines
• <i>N</i>-heterocyclic carbene precursors
• asymmetric catalysis