PALLADIUM-CATALYZED DECARBOXYLATIVE ALLYLIC ALKYLATION OF ALLYLIC ACETATES WITH BETA-KETO ACIDS
PALLADIUM-CATALYZED DECARBOXYLATIVE ALLYLIC ALKYLATION OF ALLYLIC ACETATES WITH BETA-KETO ACIDS
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DOI：
10.1021/jo00354a001
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发表时间：
1986-02-21
影响因子：
3.6
通讯作者：
SAEGUSA, T
中科院分区：
文献类型：
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作者：
TSUDA, T;OKADA, M;SAEGUSA, T
在催化量的四（三苯基膦）钯的存在下，β-酮酸与烯丙基乙酸酯在室温下反应，以良好的产率产生β-烯丙基酮，并定量脱羧。这种钯催化的乙酸烯丙酯与β-酮酸的脱羧烯丙基烷基化的特征在于高的区域和立体选择性。β-酮酸的烯丙基化发生在带有羧基的碳原子上。乙酸烯丙酯与β-酮酸的烯丙基烷基化发生在烯丙基的较少取代的末端。烯丙基酮的碳-碳双键具有E构型。内酯25与苯甲酰基乙酸的烯丙基烷基化反应在保持构型的情况下较好地进行，这表明即使在游离羧酸共存的情况下，烯醇化物也能从钯的对侧反式进攻（反-烯丙基）钯中间体。1使用酮烯醇化物作为不太稳定的亲核试剂增加了这种类型的烯丙基烷基化反应的潜力，因为酮的化学选择性烷基化是重要的合成转化。最近，我们报道了通过烯丙基/3-酮基羧酸酯的钯催化脱羧（eq 1）与酮烯醇化物的区域选择性烯丙基烷基化。2因为
In the presence of a catalytic amount of tetrakis (triphenylphosphine) palladium,/3-keto acids react with allylic acetates at ambient temperature to produce-allylic ketones in good yields with quantitative decarboxylation. This palladium-catalyzed decarboxylative allylic alkylation of allylic acetates with/3-keto acids is characterized by high regio-and stereoselectivity. Allylation of/3-keto acidtakes place at the carbon atom bearing a carboxyl group. Allylic alkylation of allylic acetate with/3-keto acid occurs at the less substituted end of the allyl group. The resultant carbon-carbon double bond of the-allylic ketone has the E configuration. Allylic alkylation of lactone 25 with benzoylacetic acid proceeds preferably with retention of configuration, indicative of trans attack of the enolate on the (ir-allyl) palladium intermediate from the opposite side of palladium even in the coexistence of free carboxylic acids.Palladium-catalyzed allylic alkylation of allylic com-pounds with stabilized carbanions has recently been de-veloped in organic synthesis. 1 Use of ketone enolate as a less stabilized nucleophile increases the potential of this type of allylic alkylation reaction, since chemoselective-alkylation of ketone is an important synthetic trans-formation. Recently, we reported regioselective allylic alkylation with ketone enolates by palladium-catalyzed decarboxylation of allylic/3-keto carboxylates (eq l). 2 For