Rearrangement of Fischer Carbene Complexes to Ketones: Stereochemistry and Mechanism

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• 作者：Kashinath M. Sathe ; Malay Nandi ; Sk. Rasidul Amin ; Vedavati G. Puranik ; and Amitabha Sarkar
• 刊名：Organometallics
• 出版年：1996
• 出版时间：June 25, 1996
• 年：1996
• 卷：15
• 期：13
• 页码：2881 - 2889
• 全文大小：372K
• 年卷期：v.15,no.13(June 25, 1996)
• ISSN：1520-6041

文摘

Fischer carbene complexes of general structure(CO)₅M=C(Ar)(OCHRAr'), where M =Cror W and R = H or Me, rearrange to ketones,ArC(O)CHRAr'Cr(CO)₃ orArC(O)CHRAr' (forM = W), on heating. For M = W and Ar' = 2-furyl, therearrangement is the most facile. Aprobable mechanism is proposed. Rearrangement also occurs with(CO)₅W=C(4-Me-C₆H₄)(OCH₂CH=CMe₂)and (CO)₅W=C(Ph)(OCH₂CH=CHPh); theketones do not result froma [3,3]-sigmatropic shift alone. Excellent diastereoselectivityis observed with (CO)₅Cr=C(Ph){OCH(Me)(C₆H₄-2-OMe)};that the product obtained is a result of kinetic controlisestablished by an equilibration experiment. The structure of thisproduct was determinedby X-ray crystallography.