Strained alkynes derived from 2,2′-dihydroxy-1,1′-biaryls; synthesis and copper-free cycloaddition with azides

A series of strained alkynes were prepared from 2,2′-dihydroxy-biaryls. Several were characterised by X-ray crystallography, revealing strained C(sp)-C(sp)-C(sp 3 ) bond angles in the range of 163-167°. Their cycloadditions with azides proceed without a catalyst. Functionalised versions of these reagents have potential applications to materials synthesis and bioconjugations. A series of strained alkynes were prepared from 2,2′-dihydroxy-biaryls, and were demonstrated to react with azides without a copper catalyst.