Alternative protecting groups and deprotection conditions.
| |||
|---|---|---|---|
| Entry | Substrate | Conditions | Product |
| 1 | 5c | H2 (1 bar), Pd/C (20%), MeOH (2 mL), rt | c6c |
| 2 | 5c | H2 (1 bar), Pd/C (20%), MeOH (2 mL), 90 °C | c6c |
| 3 | 5c | H2 (7 bar), Pd/C (20%), MeOH (2 mL), rt | c6c |
| 4 | 5c | H2 (7 bar), Pd/C (20%), MeOH (2 mL), 90 °C | c6c |
| 5 | 5d | H2 (7 bar), Pd/C (20%), MeOH (2 mL), 90 °C | c6d |
| 6 | 5d | TFA (10 equiv.), Pd/C (20%), MeOH (2 mL), 70 °C | d6d |
| 7 | 5d | TFA (47 equiv. or 1 mL per 100 mg), 100 °C | a6a |
| 8 | 5d | DDQ (1.2 equiv.), DCM : H2O (20 : 4) (5.25 mL), rt | a6a |
| 9 | 5d | Ceric ammonium nitrate (4 equiv.), MeCN : H2O (3 : 1) (4 mL), rt | e6d |
| 10b | 5e | AcOH : H2SO4 (1 : 1) (5 mL) | No product |
| 11b | 5e | NaOH (4 M) : MeOH : THF 2 : 1 : 4 (3.5 mL) 80 °C | No product |
a
Product detected by HRMS however no product obtained from purification.
b
No starting material remaining after 4 h, no product mass or peak observed.
c
Product obtained quantitatively after filtration of reaction through celite and concentration in vacuo.
d
Product obtained with 93% yield after neutralization by addition of Et3N (10 equiv.), followed by filtration of reaction through celite and concentration in vacuo.
e
Reaction on 100 μM scale, product identification achieved by HRMS.