Synthesis of Substituted Oxo-Azepines by Regio- and Diastereoselective Hydroxylation
AbstractSubstituted seven-membered N-heterocycles are prevalent bioactive epitopes and useful synthons for preparing enzyme inhibitors or molecular recognition systems. To fully exploit the chemical properties of this flexible N-heterocycle scaffold, efficient methods for its diverse functionalization are required. Here we utilize the late-stage oxidation of tetrahydroazepines as an approach to access densely functionalized oxo-azepines in a total of 8 steps and ~30% overall yield from commercially available starting materials. Hydroboration of tetrahydroazepines proceeded with diastereoselectivity in a substrate-dependent manner to yield regioisomeric azepanols before their oxidation to the corresponding oxo-azepines. Regioselectivity of the hydroboration step may be improved moderately by a rhodium catalyst, albeit with loss of conversion to a competing hydrogenation pathway. Overall our method allows efficient access to azepanols and oxo-azepines as versatile epitopes and synthons with a high degree of diastereoselectivity and moderate regioselectivity. View Full-Text
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Spedding, H.; Karuso, P.; Liu, F. Synthesis of Substituted Oxo-Azepines by Regio- and Diastereoselective Hydroxylation. Molecules 2017, 22, 1871.
Spedding H, Karuso P, Liu F. Synthesis of Substituted Oxo-Azepines by Regio- and Diastereoselective Hydroxylation. Molecules. 2017; 22(11):1871.Chicago/Turabian Style
Spedding, Harold; Karuso, Peter; Liu, Fei. 2017. "Synthesis of Substituted Oxo-Azepines by Regio- and Diastereoselective Hydroxylation." Molecules 22, no. 11: 1871.
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