Toward a Click-to-Click Strategy Enabled by Sequential Reverse Cope Cyclization and Strain-Promoted Alkyne-Nitrone
Vivien Herrscher1, Agathe Martinez1,2, Alexis Vallée1,2
1Université de Reims Champagne-Ardenne, CNRS, ICMR, Reims51687, France.
Abstract:
Primary hydroxylamines rapidly react with strained cyclooctynes under mild conditions to produce nitrones. A diverse set of RNHOH derivatives, including amino-acid- and carbohydrate-based substrates, undergo efficient coupling with BCN to furnish the corresponding nitrones in good yields. Comparison of several cyclooctynes highlights substantial differences in reactivity, with DBCO-acid displaying the fastest reaction (k2 > 23 M-1 s-1). The resulting nitrones can subsequently participate in strain-promoted alkyne-nitrone cycloaddition (SPANC) reactions, enabling a sequential "click-to-click" ligation of up to three components.
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