Table 1. Optimization of the Reaction Conditions for the MHAT Coupling to Form Phenanthridines.
| entry | deviation from optimum conditions | yield |
|---|---|---|
| 1 | no variationa | 75% |
| 2 | without heating | 63% |
| 3 | 3 equiv of oxidant | 17% |
| 4 | THF/MeOH instead of iPrOH | 23% |
| 5 | 0.2 M iPrOH instead of 0.4 Mb,c | 30% |
| 6 | 4 h instead of 24 hc | 32% |
| 7 | 2.5 equiv of PhSiH3b,c | 30% |
| 8 | 2 equiv of alkene | 40%d |
| 9 | 2 equiv of isocyanide | 40%d |
| 10 | Fe(dibm)3 instead of Fe(acac)3c | 40% |
a
Reaction conditions are as follows: isocyanide/alkene (1:1), iPrOH (0.4 M), and TBHP (70% in H2O) (1.5 equiv).
b
0.4 equiv of Fe(acac)3 was used.
c
The reaction was performed at room temperature.
d
Yield calculated with respect to the limiting reagent.