Solid-Phase [2+ 2+ 2] Cycloaddition of Resin-Bound Dipropargylamine with Alkynes

Abstract:

Significance: The resin-bound dipropargylamine 3 was prepared by treatment of commercially available trityl chloride resin 1 with dipropargylamine 2 using N, N-diisopropylethylamine as a base. The microwave-assisted iridium-catalyzed [2+ 2+ 2] cycloaddition of 3 with several alkynes 4, followed by TFA cleavage and catch–release purification with basic alumina of resin-bound intermediates 5, gave the corresponding salt-free isoindoline derivatives 6 in 50–70% yields. Comment: Previously, other groups reported the solid-phase synthesis of isoindolines via rhodiumcatalyzed [2+ 2+ 2] cycloaddition; however, the reaction time was long (12–48 h) and the HCl salt of isoindolines were obtained (Q. Sun et al. Tetrahedron Lett. 2001, 42, 6495; DD Young et al. Chem. Eur. J. 2006, 12, 5563). In this paper, the authors developed a procedure to synthesize saltfree isoindoline derivatives in short reaction time (30 min) and …

Año de publicación:

2007

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