Polyfunctional Bis‐Lewis‐Acid‐/Bis‐Triazolium Catalysts for Stereoselective 1,4‐Additions of 2‐Oxindoles to Maleimides

Enzyme‐like catalytic activity and stereoselectivity yet lacking the typical high substrate specificity of enzymes is a challenge in the development of artificial catalysts for asymmetric synthesis. Polyfunctional catalysts are considered as promising tool for achieving excellent catalytic efficiency. In this communication a polyfunctional catalyst system is reported which incorporates two Lewis acidic/Brønsted basic cobalt centers in combination with triazolium moieties which are crucial for high reactivity and excellent stereoselectivity in the direct 1,4‐addition of oxindoles to maleimides. The catalyst is assembled via click chemistry and readily recyclable via precipitation by making use of its charges. Kinetic studies support a cooperative mode of action. Diastereodivergency is achievable using either Boc‐ or unprotected oxindoles.

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