DFT Rationalization of the Diverse Outcomes of the Iodine(III)-Mediated Oxidative Amination of Alkenes.
A computational study of the mechanism for the iodine(III)-mediated oxidative amination of alkenes explains the experimentally observed substrate dependence on product distribution. Calculations with the M06 functional have been carried out on the reaction between PhI(N(SO2 Me)2 )2 and three different representative substrates: styrene, α-methylstyrene, and (E)-methylstilbene. All reactions start with electrophilic attack by a cationic PhI(N(SO2 Me)2 )(+) unit on the double bond, and formation of an intermediate with a single C-I bond and a planar sp(2) carbocationic center. The major path, leading to 1,2-diamination, proceeds through a mechanism in which the bissulfonimide initially adds to the alkene through an oxygen atom of one sulfonyl group. This behavior is now corroborated by experimental evidence. An alternative path, leading to an allylic amination product, takes place through deprotonation at an allylic C-H position in the common intermediate. The regioselectivity of this amination depends on the availability of the resonant structures of an alternate carbocationic intermediate. Only in cases where a high electronic delocalization is possible, as in (E)-methylstilbene, does the allylic amination occur without migration of the double bond.
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
Ignacio
http://orcid.org/0000-0002-5843-9660
I
Funes-Ardoiz
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.|Fukui Institute for Fundamental Chemistry, Kyoto University, 606-8103, Kyoto, Japan.
W M C
WM
Sameera
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
R Martín
RM
Romero
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
Claudio
http://orcid.org/0000-0003-0390-9941
C
Martínez
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain.
José A
JA
Souto
Departamento de Química, Centro de Investigación en Síntesis Química (CISQ), Universidad de La Rioja, C/Madre de Dios, 51, 26006, Logroño, Spain.
Diego
http://orcid.org/0000-0003-2772-6453
D
Sampedro
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain. kmuniz@iciq.es.|Catalan Institution for Research and Advanced Studies (ICREA), Pg. Lluís Companys 23, 08010, Barcelona, Spain. kmuniz@iciq.es.
Kilian
http://orcid.org/0000-0002-8109-1762
K
Muñiz
Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007, Tarragona, Spain. fmaseras@iciq.es.|Departament de Química, Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain. fmaseras@iciq.es.
Feliu
http://orcid.org/0000-0001-8806-2019
F
Maseras
alkenes; amination; density functional calculations; hypervalent iodine; reaction mechanisms