Synthesis of (E)-2-(1-ferrocenylmethylidene)malonic acid derivatives by a cobalt-catalyzed domino reaction of ethyl diazoacetate, carbon monoxide and ferrocenylimines

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• 作者：Já ; nos Balogh^a ; Tamá ; s Ké ; gl^a ; ^b ; Lá ; szló ; Pá ; rká ; nyi^c ; Lá ; szló ; Kollá ; r^b ; Ferenc Ungvá ; ry^a ; Rita Skoda-Fö ; ldes^a ; ^{skodane@almos.uni-pannon.hu}
• 关键词：Domino reactions ; β ; -Lactams ; Cobalt-catalysis ; Carbonylation
• 刊名：Journal of Organometallic Chemistry
• 出版年：2011
• 出版时间：1 April 2011
• 年：2011
• 卷：696
• 期：7
• 页码：1394-1403
• 全文大小：916 K

文摘

The domino reaction of ethyl diazoacetate, carbon monoxide and ferrocenylimines was investigated in the presence of Co₂(CO)₈ as catalyst. In most cases the main products are 2-(1-ferrocenylmethylidene) malonates formed by an N(1)–C(4) cleavage of the primarily derived β–lactams. The latter compounds could only be isolated when the reaction was carried out at relatively low CO pressure, using an excess of ethyl diazoacetate. trans-N-(tert-Butyl)-3-ethoxycarbonyl-4-ferrocenyl-β-lactam proved to be the most stable one among these compounds and could be isolated in 55 % yield. N-alkyl β-lactams were shown to undergo acidic cleavage leading to the E isomers of 2-(1-ferrocenylmethylidene) malonates as the main products. The structures of the two new compounds, (E)-2-ethoxycarbonyl-3-ferrocenyl-N-((R)-1-phenylethyl)-2-propenamide and trans-N-(tert-butyl)-3-ethoxycarbonyl-4-ferrocenyl-β-lactam were confirmed by X-ray crystallography. The relative thermodynamical stability of the products as well as the energetics of the acid-mediated cleavage of the β-lactam ring was elucidated with DFT calculations.