Table 3.
Optimization reactions for the synthesis of dioxolanes from racemic 3,4‐hexanediol and 4,5‐octanediol.
|
| |||||
|---|---|---|---|---|---|
|
Entry[a] |
Substrate (x mmol) |
Formic acid [mL] |
TON[d] (RR,SS) |
TON[d] (meso) |
Yield of acetals[d] [%] |
|
1[b] |
3,4‐hexanediol (1.9) |
0.3 |
41 |
10 |
9 |
|
2 |
3,4‐hexanediol (1.9) |
0.3 |
70 |
17 |
15 |
|
3 |
3,4‐hexanediol (1.4) |
0.3 |
59 |
17 |
18 |
|
4 |
3,4‐hexanediol (1.9) |
0.6 |
62 |
17 |
14 |
|
5[c] |
3,4‐hexanediol (1.9) |
2×0.3 |
101 |
32 |
23 |
|
6[c] |
3,4‐hexanediol (1.9) |
3×0.3 |
100 |
26 |
22 |
|
7 |
4,5‐octanediol (1.4) |
0.3 |
41 |
25 |
16 |
|
8[c] |
4,5‐octanediol (1.4) |
2×0.3 |
46 |
27 |
17 |
[a] Ru(triphos)(tmm) (0.003 mmol), Bi(OTf)3 (0.032 mmol), formic acid (0.3 mL), CPME (2 mL) 90 °C, 16 h, H2 100 bar. [b] 1,4‐Dioxane (2 mL). [c] Reloaded once/twice with additional formic acid (0.3 mL) after 16 h, respectively, 32/48 h reaction time. [d] TON=turnover number; TON and yield were determined by 1H NMR spectroscopy using mesitylene as internal standard.