oxidation catalysis employing bromine has remained largely unexplored. We herein show that the combination of a tetraalkylammonium bromide and meta‐chloroperbenzoic acid offers a unique catalyst system for the convenient and selective oxidation of saturated C(sp3)−H bonds upon photochemical initiation with day light. This approach enables remote, intramolecular, position‐selective C−H amination as demonstrated
Enantio‐ and Regioselective Palladium(II)‐Catalyzed Dioxygenation of (Aza‐)Alkenols
作者:Sabrina Giofrè、Letizia Molteni、Donatella Nava、Leonardo Lo Presti、Egle Maria Beccalli
DOI:10.1002/anie.202109312
日期:2021.9.27
An oxidative Pd-catalyzed intra-intermolecular dioxygenation of (aza-)alkenols has been reported, with total regioselectivity. To study the stereoselectivity, different chiral ligands as well as different hypervalent-iodine compounds have been compared. In particular, by using a C-6 modified pyridinyl-oxazoline (Pyox) ligand and hypervalent iodine bearing an aromatic ring, an excellent enantio- and
An Intramolecular Iodine‐Catalyzed C(sp
<sup>3</sup>
)−H Oxidation as a Versatile Tool for the Synthesis of Tetrahydrofurans
作者:Vanessa Koch、Stefan Bräse
DOI:10.1002/ejoc.202100652
日期:2021.6.25
The first iodine-catalyzed cyclization reaction of aliphatic primary and secondary alcohols gives access to tetrahydrofurans through an intramolecular C(sp3)−H activation. The reaction proceeds under mild reactions using either a floodlight lamp or daylight.
and ecologically benign alternatives to transition metals, although their application as molecular catalysts in challenging CH oxidation reactions has remained elusive. An attractive iodine oxidation catalysis is now shown to promote the convenient conversion of carbon–hydrogenbonds into carbon–nitrogen bonds with unprecedented complete selectivity. The reaction proceeds by two interlocked catalytic
A Pd-catalyzed method based on the use of a molecular tether is described for olefin difunctionalization. Enabled by an easily introduced trifluoroacetaldehyde-derived tether, a simultaneous introduction of oxygen and nitrogen heteroatoms across unsaturated carbon–carbon bonds was achieved under oxidative conditions, most probably via high-valent Pd intermediates. Good yields and high diastereoselectivity