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An Integrated NMR and DFT Study on the Single Insertion of α‐Olefins into the MC Bond of Group 4 Metallaaziridinium Ion Pairs
Author(s) -
Rocchigiani Luca,
Ciancaleoni Gianluca,
Zuccaccia Cristiano,
Macchioni Alceo
Publication year - 2013
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200341
Subject(s) - heptene , chemistry , diastereomer , olefin fiber , regioselectivity , nuclear magnetic resonance spectroscopy , density functional theory , spectroscopy , insertion reaction , crystallography , computational chemistry , stereochemistry , organic chemistry , catalysis , bicyclic molecule , physics , quantum mechanics
The reactions of metallaaziridinium ion pairs [Cp 2 M(η 2 ‐CH 2 NMePh)][B(C 6 F 5 ) 4 ] [M=Zr ( 1 ), Hf ( 2 )] with 1‐hexene and 2‐methyl‐1‐heptene were investigated by means of NMR spectroscopy and DFT calculations. We found that a single insertion of the olefin into the MC bond led to the formation of stable five‐membered heterocycles ( 3 – 6 ). The reactions were 1,2‐regioselective and afforded two diastereoisomers whose ratio was mainly controlled by the nature of the olefin, whilst the nature of the metal only played a marginal role. In particular, the reaction with 1‐hexene was found to be not only more favored than that with 2‐methyl‐1‐heptene from a thermodynamic point of view but it was also more diastereoselective. In all cases, the observed diastereoisomeric ratio was dictated by thermodynamics because the products interconverted into each other, as indicated by EXSY NMR spectroscopy and by DFT calculations.