Table 4.
Synthesis of dimethyl isosorbide (DMI) by DMC chemistry.a
| entry | Base | Temp | Selectivity (%)b | ||||
| (equiv) | (°C) | DMI | MMI-1 | MMI-2 | MCEI-1 | MCEI-2 | |
| 1 | t-BuOK (1.5) | 90 | 40 | 2 | 2 | 37 | 18 |
| 2 | NaOMe (1.5) | 90 | 26 | 11 | 6 | 30 | 12 |
| 3 | NaOMe (3.0) | 90 | 100 | 0 | 0 | 0 | 0 |
| 4c | K2CO3 (1.0) | 200 | 57 | 4 | 7 | 29 | 0 |
| 5c | t-BuOK (1.0) | 200 | 55 | 5 | 6 | 34 | 0 |
| 6c | KW2000d | 180 | 83 | 1 | 3 | 12 | 0 |
| 7c | KW2000d | 200 | 86 | 0 | 2 | 12 | 0 |
aReaction conditions: Isosorbide DMC 1:50 equiv; Reaction time 20 h; Conversion 100%. bCarboxymethyl derivatives MCI-1, MCI-2 and DC have been detected only in traces. cReaction conducted in an autoclave under pressure. dHydrotalcite was calcinated at 400 °C overnight prior its use.