Table 1.
Optimization of reaction conditions.[a]
|
Entry |
Photocatalyst[b] |
(e− + H+) Donor + HAT Reagent |
Yield [%][c] |
|---|---|---|---|
|
1 |
– |
DIPEA |
<5 |
|
2 |
1 |
DIPEA |
88 |
|
3 |
2 |
DIPEA |
47 |
|
4 |
Riboflavin tetraacetate |
DIPEA |
– |
|
5 |
3 |
DIPEA |
6 |
|
6 |
Rhodamine 6G |
DIPEA |
<5 |
|
7 |
1 |
NEt3 |
83 |
|
8 |
1 |
tributylamine |
85 |
|
9 |
1 |
NPh3 |
– |
|
10 |
1 |
pyridine |
– |
|
11 |
1 |
DIPEA + Hantzsch ester |
87 |
|
12 |
1 |
DIPEA + MeNH3Cl |
89[d] |
[a] The reactions were performed using 0.1 mmol 4 a in 1 mL DMF under air. [b] The triplet state energy decreases in the order 1>2>Riboflavin tetraacetate>3>Rhodamine 6G. [c] Yields were determined by GC analysis with naphthalene as an internal standard. [d] Reaction time=0.5 h.