Rhodium(II)-catalyzed one-pot four-component synthesis of functionalized polyether macrocycles at high concentration

Abstract

Against conventional wisdom, the rhodium(II)-catalyzed nontemplated macro-cyclization of four separate components in one reaction vessel became more efficient as the concentration was increased. Thus, a-diazo-p-ketoesters underwent condensation with 1,4-diox-ane, 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, PhCH=CH2). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.