Synthesis of carboxylic esters from aldehydes using metal carbonyl anions, part 2. Dimerization of aldehydes to carboxylic esters catalyzed by disodium pentacarbonylchromate, na2[cr(co)5]
✍ Scribed by Takahiro Ohishi; Tokuji Matsumoto; Masakazu Yamashita
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 337 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0268-2605
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✦ Synopsis
Na,[Cr(CO),] (1) was found to be an efficient catalyst for the dimerization of aldehydes to carboxylic esters. Several aromatic aldehydes including furfural gave the corresponding esters in good yields. This reaction also proceeded intramolecularly to give phthalide from phthalaldehyde. Compared with M,[Fe(CO),] (M = Na, K), 1 was found to be a more efficient catalyst for this reaction. However, aliphatic aldehydes gave aldolcondensation products instead of the corresponding esters. In the reactions of p-substituted benzaldehydes with 1, the reactivity decreased with the increase of the electron-releasing ability of the substituents. However, even p-anisaldehyde, which hardly reacted with M,[Fe(CO)J, reacted with 1 to give the ester in moderate yield. The reaction mechanism, including the nucleophilic attack of the pentacarbonylchromate dianion on the carbonyl carbon, is discussed.