An efficient rhodium(III)-catalyzed redox-neutral C-H activation/cyclization/isomerization strategy to prepare isoquinolines with complete regioselectivity from aromatic oxime esters and diverse 1,3-dienes is described. The advantages of this process are: (1) no need for an external oxidant; (2) simple and convenient reaction conditions; (3) complete regioselectivity; (4) broad scope of substrates.Scheme 1 Isoquinoline synthesis via C-H activation with alkynes.Scheme 2 Inspiration for isoquinoline synthesis from 1,3-dienes.
The Rh(III)-catalyzed selective bromination and iodination of electron-rich heterocycles is reported. Kinetic investigations show that Rh plays a dual role in the bromination, catalyzing the directed halogenation and preventing the inherent halogenation of these substrates. As a result, this method gives highly selective access to valuable halogenated heterocycles with regiochemistry complementary to those obtained using uncatalyzed approaches, which rely on the inherent reactivity of these classes of substrates. Furans, thiophenes, benzothiophenes, pyrazoles, quinolones, and chromones can be applied.
An experimentally simple additive-free Rh(III)-catalysed direct alkynylation of alkenes has been developed. This protocol employs commercially available TIPS-EBX as the alkyne source, giving access to conjugated terminal enynes following a simple silyl-deprotection. This method has also been applied to arenes.
Molecule deposition on a prepatterned substrate is a recently developed technique to generate desired structures of organic molecules on surfaces via self-organization. For the case of prepatterned stripes, the time-resolved process of structure formation is studied via lattice Monte Carlo simulations. By systematic variation of the interaction strength, three distinct growth regimes can be identified: localized growth, bulge formation, and cluster formation. All three growth regimes can be recovered in the experiment when choosing appropriate organic molecules. Some key microscopic observables, reflecting the properties of the structure formation, display a non-monotonous dependence on the interaction strength.
The ortho- and monoselective Cp*Rh(III)-catalyzed
chlorination of a broad range of benzene derivatives and electron-rich
heterocycles under mild reaction conditions is reported. Inexpensive
and commercially available N-chloro-imides could
be used as chlorinating agents in as low as substoichiometric quantities.
Furthermore, two different reaction protocols were developed to allow
for the use of substrates with various electronic properties and enable
selective chlorination of a broad range of structural motifs. For
electron-rich substrates, the reported protocols enable a perfectly
regio-switchable and efficient direct chlorination.
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