118522-23-9Relevant academic research and scientific papers
Highly selective intramolecular carbene insertion into primary C-H bond of α-diazoacetamides mediated by a (p-cymene)ruthenium(II) carboxylate complex
Lo, Vanessa Kar-Yan,Guo, Zhen,Choi, Matthew Kwok-Wai,Yu, Wing-Yiu,Huang, Jie-Sheng,Che, Chi-Ming
, p. 7588 - 7591 (2012/07/02)
Complex [(p-cymene)Ru(η1-O2CCF3) 2(OH2)] mediated transformation of α-diazoacetamides ArCH2N(C(CH3)3)C(O)CHN2 to result in carbene insertion into the primary C-H bond exclusively, with the γ-lactam products being isolated in up to 98% yield. This unexpected reaction is striking in view of the presence of usually more reactive sites such as secondary C-H bonds in the substrates. DFT calculations based on proposed Ru-carbene species provide insight into this unique selectivity.
Ligand effects on dirhodium(II) carbene reactivities. Highly effective switching between competitive carbenoid transformations
Padwa, Albert,Austin, David J.,Price, Alan T.,Semones, Mark A.,Doyle, Michael P.,Protopopova, Marina N.,Winchester, William R.,Tran, Andrea
, p. 8669 - 8680 (2007/10/02)
Carboxylate and carboxamide ligands of dirhodium(II) catalysts control chemoselectivity in competitive metal carbene transformations of diazo compounds. For competitive intramolecular cyclopropanation versus intramolecular aromatic substitution with 1-diazo-3-aryl-5-hexen-2-ones, use of Rh2(OAc)4 results in the products from both transformations in nearly equal amounts, but dirhodium(II) perfluorobutyrate (Rh2(pfb)4) provides only the aromatic substitution product while dirhodium(II) caprolactamate (Rh2(cap)4) gives only the cyclopropanation product. Similar results are obtained from dirhodium(II) catalysts in competitive intramolecular cyclopropanation versus tertiary C-H insertion, aromatic cycloaddition versus C-H insertion, cyclopropanation versus aromatic cycloaddition, and C-H insertion versus aromatic substitution. The order of reactivity for metal carbenes generated from Rh2(pfb)4 is aromatic substitution > tertiary C-H insertion > cyclopropanation ～ aromatic cycloaddition > secondary C-H insertion, and the rate differences between them are as much as 100-fold. For Rh2(cap)4 the order of reactivity is cyclopropanation > tertiary C-H insertion > secondary C-H insertion > aromatic cycloaddition with aromatic substitution not observed as a competing process for the diazo compounds examined. Control of chemoselectivity through charge and/or frontier molecular orbital properties of the intermediate metal carbene has been evaluated. Competitive product formation from dirhodium(II) caprolactamate catalyzed reactions of N-tert-butyl-N-benzyldiazoacetoacetamide is temperature dependent over a narrow 15-deg range. The effect of carbene substituents other than the ligated dirhodium(II) on chemoselectivity is described and discussed.
