Atmospheric Pressure Carbonylation of Allylic Compounds

钯催化烯丙基化合物羰基化提供了一种合成α， β -不饱和酸的方法。然而，羰基化的应用较少，因为它需要很高的一氧化碳压力。几年前，我们发现常压羰基化在室温下，在强碱如或存在的情况下，进行得很顺利。因此，必须缓慢地、滴入地向烯丙基卤化物中加入醇酸钠，以避免碱过量。本研究以肉桂酰氯为底物，对反应过程和催化剂体系进行了简化和优化。作为aq. NaOH/有机溶剂pDCl_2p[ph_2p(m-C_6H_4SO_3Na)]_2双相反应的催化剂，在产率和CO吸收率方面效果最好。我们考虑了一种可能性，即容易羰基化涉及CO插入到pd-O键，而不是pd-C键。这一过程似乎很可能发生在水相中。在均相CH_3ONa/CH_3OH体系羰基化反应中，Na_2PdCl_<4′>不含磷配体，产率高。另一方面，钯与磷配体的配合物以甲基醚为主要产物。磷配体的存在显著影响羰基化反应。需要做更多的工作来确定这种羰基化的途径。

The palladium-catalyzed carbonylation of allylic compounds offers a synthetic method of alpha, beta-unsaturated acid. However, the carbonylation has found less application, because it requires a high carbon monoxide pressure. Several years ago we have found that the atmospheric pressure carbonylation proceeds smoothly at room temperature in the presence of strong bases such as or It was necessary to add sodium alkoxide slowly and dropwise to the allylic halides, to avoid an excess of the bases.In the present study we aimed at simplifying the reaction procedure and the catalyst system and optimizing the reaction using cinnamyl chloride as the substrate. As the catalyst of the biphasic reaction of aq. NaOH/organic solvent pDCl_2p[ph_2p(m-C_6H_4SO_3Na)]_2 gave the best results in terms of yield and rate of CO uptake. We considered a possibility that the facile carbonylation involved the CO insertion into a pd-O bond, rather than a pd-C bond. It seemed likely that this process occurs in the aqueous phase.In the carbonylation of the homogeneous CH_3ONa/CH_3OH system, Na_2PdCl_<4'> without any phosphorus ligand, gave methyl esters in high yields. On the other hand, palladium complexes with phosphorus ligand gave methyl ethers as the major product. The presence of the phosphorus ligand affects the carbonylations significantly.More work is needed to define the pathway of this carbonylation.