Rh-Catalyzed [7 + 1] Cycloaddition of Buta-1,3-dienylcyclopropanes and CO for the Synthesis of Cyclooctadienones
作者:Zhong-Ke Yao、Jianjun Li、Zhi-Xiang Yu
DOI:10.1021/ol102700m
日期:2011.1.7
advance transition-metal-catalyzed cycloadditions for the synthesis of various-sized ring compounds. A new seven-carbon building block from buta-1,3-dienylcyclopropanes (BDCPs) has been developed, showing that, under the catalysis of [Rh(CO)2Cl]2, BDCPs react with CO to give [7 + 1] cycloaddition products, cyclooctadienones. The present [7 + 1] reaction provides an efficient entry to the synthetically
The reaction of α-diazoacetophenone with olefinic compounds, such as vinyl acetate, cis- and trans-stilbenes and cyclohexene, has been studied in the presence of bis(acetylacetonato)copper-(II). The reaction gave the corresponding cyclopropane derivatives, the addition products of benzoylcarbene to the double bond of olefinic compounds in good yields, accompanied by cis-and trans-dibenzoylethylenes, dibenzoylethane or dilactone. Addition of carbene was found to be stereospecific in the cases of cis- and trans-stilbenes. A mechanism has been advanced in which a ketocarbene-metal chelate complex is included as an intermediate of the reaction.