Table 1 Screening and optimization of the reaction conditions for the conversion of semi-protected 1,4-alkyne diol 1a into targeted seven-membered acyl cyclic carbonate 3aa
| |||||
|---|---|---|---|---|---|
Entry | Base (mol%) | Solv. | Conv. 1a (%)b | 3a (%)b | 4a (%)b |
1 | DIPEA, 10 | ACN | 29 | 12 | – |
2 | NMM, 10 | ACN | 24 | 20 | – |
3 | DMAP, 10 | ACN | 51 | 46 | – |
4 | DAMP, 20 | ACN | 64 | 57 | – |
5 | DBU, 10 | ACN | > 99 | < 10 | 24 |
6 | DABCO, 10 | ACN | 65 | 54 | – |
7 | DABCO, 20 | ACN | 90 | 75 (73)c | – |
8 | DABCO, 30 | ACN | > 95 | 56 | – |
9 | TBD, 20 | ACN | > 99 | d | d |
10 | DBN, 20 | ACN | > 99 | d | d |
11 | HQ, 20 | ACN | > 95 | 46 | – |
12 | QUI, 20 | ACN | 94 | 70 | – |
13 | DABCO, 20 | THF | 45 | 30 | – |
14 | DABCO, 20 | DCM | > 95 | 79 (78)c | – |
15 | DABCO, 20 | Tol | 90 | 28 | – |
16e | DABCO, 20 | DCM | > 95 | 56 | trace |
