Hypervalent Iodine Reagents Enable C-H Alkynylation with Iminophenylacetic Acids via Alkoxyl Radicals

Here we report (delta-C-H alkynylation to synthesize various (delta-alkynols from iminophenylacetic acids. The hypervalent iodine-coordinated benziodoxole-alkoxyl-iminophenylacetic acid complex was the key intermediate and was characterized by X-ray crystallography for the first time. (delta-C-H alkynylation is compatible with sensitive functional groups, including azides, aldehydes, and free alcohols, for the synthesis of (delta-alkynols with diversified substituents in excellent regioselectivity. This reaction extends to (delta-hydroxylalkene and (delta-hydroxylnitrile synthesis, and the (delta-alkynol products are easily derivatized to other valuable bifunctional building blocks.

Automated summary

In this study, a method for synthesizing various delta-alkynols through delta-C-H alkynylation is reported. The key intermediate, a hypervalent iodine-coordinated benziodoxole-alkoxyl-iminophenylacetic acid complex, was characterized by X-ray crystallography for the first time. The reaction is compatible with sensitive functional groups and exhibits excellent regioselectivity for the synthesis of delta-alkynols with diverse substituents. Furthermore, the method can be extended to the synthesis of delta-hydroxylalkenes and delta-hydroxylnitriles, and the resulting delta-alkynol products can be easily derivatized to other valuable bifunctional building blocks.