124. Rhodium(II)-Catalyzed One-Pot Four-Component Synthesis of Functionalized Polyether Macrocycles at High Concentration
     Walid Zeghida, Céline Besnard, Jérôme Lacour
     Angew. Chem. Int. Ed. 2010, 49, 7253-7256
     [ Selected as a hot paper. Highlighted in CHIMIA Swiss Science Concentrates. ]

Against conventional wisdom, the rhodium(II)-catalyzed nontemplated macrocyclization of four separate components in one reaction vessel became more efficient as the concentration was increased. Thus, α-diazo-β-ketoesters underwent condensation with 1,4-dioxane, tetrahydrofuran, or tetrahydropyran as the solvent to yield 16- to 18-membered polyether macrocycles in up to 75 % yield (see scheme; R=Me, Et, PhCH₂CH₂, allyl, PhCHCH₂).

DOI: 10.1002/anie.201003559 

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