The second step was their catalytic debenzylation
using hydrogen gas and Pd/C as catalyst to obtain the respective N-unprotected tetrahydroquinolines 6 (Figure 1).
In the present study we monitored CYP3A4 activity by the debenzylation
of luciferin 6' benzyl ether into luciferase substrate.
Catalytic hydrogenation of 3 affected both debenzylation
and the desired partial reduction of the furanone ring system to produce 5, a formal precursor to 1 (Saniere et al.
, they were converted to HC1 salts.