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1.6.3 Nitroalkylation of Allylic Alcohols
ОглавлениеUnactivated nitroalkenes (mainly nitromethane) can be added to vinyl epoxides, under Pd(0) catalysis, affording nitroalkenols (Scheme 1.20).
Scheme 1.18 Nitromethylation of aryl halides.
Scheme 1.19 Nitroalkylation of aryl halides.
Table 1.6 Asymmetric nitromethylation of cyclic allyl esters (selected examples).
| Substrate | Reaction conditions | Nitroalkane | Yield (%), (ee) |
|---|---|---|---|
| CH3NO2/CH2Cl2, Pd2(dba)3, ligand, BSA | 82 (99%) | ||
| CH3NO2/CH2Cl2, Pd2(dba)3, ligand, Bu4NCl/BSA | 99 (99%) | ||
| CH3NO2/CH2Cl2, Pd2(dba)3, ligand, BSA | 84 (99%) | ||
| CH3NO2/CH2Cl2, Pd2(dba)3, ligand, Bu4NCl/BSA | 74 (99%) |
Scheme 1.20 Nitroalkanes addition to vinylepoxides under Pd(0) catalysis.
Table 1.7 Two-step process of nitro alkylation of allylic alcohols (selected examples).
| Allylic alcohol | Nitroalkane | Yield (%) |
|---|---|---|
| 62 | ||
| 74 | ||
| 70 | ||
| 71 | ||
| 63 |
Developing this result, Deardorff et al. [43] reported a two-step process for nitromethylation of allylic alcohols that include (i) the preparation of the corresponding allylic carbonate and (ii) the addition of nitromethane, under Pd2(dba)3 catalysis.
So, this procedure represents a useful method for the synthesis of functionalized nitroalkanes and some of the most representative examples are reported in Table 1.7.
