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Synthesis of α-hydroxyalkyl dehydroazepanes via catalytic enantioselective borylative migration of an enol nonaflate

Author:
Clement, Helen A., Hall, Dennis G.
Source:
Tetrahedron letters 2018 v.59 no.49 pp. 4334-4339
ISSN:
0040-4039
Subject:
aldehydes, catalytic activity, chemical reactions, chemical structure, enantioselectivity, enols, nitrogen, palladium, piperidine alkaloids, solvents
Abstract:
A Pd-catalyzed borylative migration methodology for cyclic enol perfluorosulfonates was applied to the synthesis of the corresponding 7-membered, azepane ring system. Throughout the optimization, it was shown that the reaction is sensitive to the nitrogen protecting group as well as the type of base and solvent. The resulting cyclic allylboronate reacts stereoselectively with aldehydes for the synthesis of novel α-hydroxyalkyl dehydroazepanes in good yield and enantioselectivity over two steps. We highlight the utility of this methodology with an efficient synthesis of the de novo 7-membered ring analogue of the piperidine alkaloid β-conhydrine.
Agid:
6216409