Abstract
A simple, mild and practical cascade process for the direct conversion of aldehydes to cyanamides was developed featuring a wide substrate scope and great functional group tolerability. This method allows for transformations of readily available, inexpensive, and abundant aldehydes to highly valuable cyanamides in a pot, atom, and step-economical manner with a green nitrogen source. This protocol will serve as a robust tool for the installation of the cyanamide moiety in various complicated molecules.
Highlights
A simple, mild and practical cascade process for the direct conversion of aldehydes to cyanamides was developed featuring a wide substrate scope and great functional group tolerability
Our group reported a mild and robust method for efficiently converting aldoximes into the corresponding nitriles mediated by SO2F2/base in a green manner (Scheme 1, a).20a Subsequently, an efficient method for the activation of the Beckmann rearrangement of ketoximes into amides or lactams utilizing SO2F2 was developed in our lab(Scheme 1, b).20b Coincidentally, we found that SO2F2 could promote the Tiemann rearrangement of amidoximes which were generated from corresponding nitriles to generate the corresponding cyanamides in good to excellent yields (Scheme 1, c).20c Upon viewing the high value of cyanamide moieties, the easy availability of aldehydes, and our continuous efforts on the utilization of SO2F2 for chemical transformations of oximes
(aldoximes, ketoximes, and amidoximes),[20] we proposed a onepot process for direct conversion of aldehydes to cyanamides through a cascade sequence following similar mechanism as our cascade nitrile synthesis process
Summary
A simple, mild and practical cascade process for the direct conversion of aldehydes to cyanamides was developed featuring a wide substrate scope and great functional group tolerability. We envisioned that in common polar solvent acetonitrile (CH3CN), aldehydes 1 would react with NH2OH to provide the aldoxime intermediate A a er dehydration, and the aldoxime will further react with SO2F2 to generate the corresponding sulfonyl ester B, and with the assistance of the base, the following b-elimination of the precursor sulfonyl ester B would generate the desired carbon– nitrogen triple bonds of nitriles C.
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