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Divergent Reactivity of In Situ Generated Metal Azides: Reaction with N , N ‐Bis(oxy)enamines as a Case Study
Author(s) -
Zhmurov Petr A.,
Khoroshutina Yulia A.,
Novikov Roman A.,
Golovanov Ivan S.,
Sukhorukov Alexey Yu.,
Ioffe Sema L.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605390
Subject(s) - chemistry , regioselectivity , reactivity (psychology) , azide , bond cleavage , stereocenter , medicinal chemistry , nucleophile , ionic bonding , amination , nucleophilic substitution , metal , organic chemistry , ion , enantioselective synthesis , catalysis , medicine , alternative medicine , pathology
Metal azides generated in situ by ion exchange exhibit divergent reactivity in reaction with cyclic N ‐alkoxy, N ‐siloxy‐enamines. Depending on the nature of metal and the [M]/N 3 − ratio, addition of the azide ion to the C,C‐double bond proceeds with regioselective cleavage of either exo ‐ or endo ‐cyclic N−O bond leading to cyclic or open‐chain α‐azidooxime derivatives, respectively. Mechanistic studies in combination with solvent state FTIR spectroscopy and DFT calculations revealed that covalently bound metal azides (Co, Cu, Zn) transfer N 3 − anion to the C,C‐double bond through a Lewis acid‐assisted S N ′ substitution of trialkylsilyloxy‐group. More ionic metal azides (N1, Mg, Al, Sc, Ni, Yb) tend to react by initial nucleophilic attack of N 3 − anion on the silicon atom generating conjugated nitrosoalkenes. α‐Azidooxime derivatives prepared by using the designed protocols were stereoselectively reduced to valuable 1,2‐diaminoalcohols bearing up to four contiguous stereogenic centers. By reducing the α‐azidooxime fragment in a stepwise manner site‐selective protection and reductive amination of each of the emerging primary amino groups was achieved.