177. Kinetics of Rh(II)-Catalyzed α-Diazo-β-ketoester Decomposition and Application to the [3+6+3+6] Synthesis of Macrocycles on a Large Scale and at Low Catalyst Loadings
     Daniele Poggiali, Alexandre Homberg, Timothée Lathion, Claude Piguet, Jérôme Lacour
     ACS Catal. 2016, 6, 4877-4881
     [ ACS Editors' Choice]

In the context of [3+6+3+6] macrocyclization reactions, precise kinetics of α-diazo-β-ketoester decomposition were measured by in-situ IR monitoring. Dirhodium complexes of Ikegami-Hashimoto type – and perchlorinated phthalimido derivatives in particular – performed better than classical achiral complexes. Clear correlations were found between speciation among dirhodium species and catalytic activity. With these results, novel cyclohexyl-derived catalysts were developed affording good yields of macrocycles (up to 78%), at low catalyst loadings (0.01 to 0.001 mol%) and on large scale (1 to 20-gram).

DOI : 10.1021/acscatal.6b01283 

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