Hydantoin-bridged medium ring scaffolds by migratory insertion of urea-tethered nitrile anions into aromatic C–N bonds |
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Authors: | Makenzie J Millward Emily Ellis John W Ward Jonathan Clayden |
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Institution: | School of Chemistry, University of Bristol, Cantock''s Close, Bristol BS8 1TS UK, |
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Abstract: | Bicyclic or tricyclic nitrogen-containing heterocyclic scaffolds were constructed rapidly by intramolecular nucleophilic aromatic substitution of metallated nitriles tethered by a urea linkage to a series of electronically unactivated heterocyclic precursors. The substitution reaction constitutes a ring expansion, enabled by the conformationally constrained tether between the nitrile and the heterocycle. Attack of the metallated urea leaving group on the nitrile generates a hydantoin that bridges the polycyclic products. X-ray crystallography reveals ring-dependant strain within the hydantoin.Bicyclic or tricyclic nitrogen-containing heterocyclic scaffolds were constructed rapidly by ring expanding intramolecular SNAr on a series of electronically unactivated heterocyclic precursors. |
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