Reported herein is a new iron-catalyzed diastereo-selective olefin diazidation reaction which occurs at room temperature (1-5 mol % of catalysts and d.r. values of up to > 20:1). This method tolerates a broad range of both unfunctionalized and highly functionalized olefins, including those that are incompatible with existing methods. It also provides a convenient approach to vicinal primary diamines as well as other synthetically valuable nitrogen-containing building blocks which are difficult to obtain with alternative methods. Preliminary mechanistic studies suggest that the reaction may proceed through a new mechanistic pathway in which both Lewis acid activation and iron-enabled redox-catalysis are crucial for selective azido-group transfer.
An
iron-catalyzed diastereoselective intermolecular olefin
amino-oxygenation reaction is reported, which proceeds via
an iron-nitrenoid generated by the N–O bond cleavage of a functionalized
hydroxylamine. In this reaction, a bench-stable hydroxylamine derivative
is used as the amination reagent and oxidant. This method tolerates
a range of synthetically valuable substrates that have been all incompatible
with existing amino-oxygenation methods. It can also provide amino
alcohol derivatives with regio- and stereochemical arrays complementary
to known amino-oxygenation methods.
We herein report an iron-catalyzed direct diazidation method via activation of bench-stable peroxyesters promoted by nitrogen-based ligands. This method is effective for a broad range of olefins and -heterocycles, including those that are difficult substrates for the existing olefin diamination and diazidation methods. Notably, nearly a stoichiometric amount of oxidant and TMSN are sufficient for high-yielding diazidation for most substrates. Preliminary mechanistic studies elucidated the similarities and differences between this method and the benziodoxole-based olefin diazidation method previously developed by us. This method effectively addresses the limitations of the existing olefin diazidation methods. Most notably, previously problematic nonproductive oxidant decomposition can be minimized. Furthermore, X-ray crystallographic studies suggest that an iron-azide-ligand complex can be generated in situ from an iron acetate precatalyst and that it may facilitate peroxyester activation and the rate-determining C-N bond formation during diazidation of unstrained olefins.
We herein report a new catalytic method for intermolecular olefin aminofluorination using earth-abundant iron catalysts and nucleophilic fluoride ion. This method tolerates a broad range of unfunctionalized olefins, especially nonstyrenyl olefins that are incompatible with existing olefin aminofluorination methods. This new iron-catalyzed process directly converts readily available olefins to internal vicinal fluoro carbamates with high regioselectivity (N vs F), many of which are difficult to prepare using known methods. Preliminary mechanistic studies demonstrate that it is possible to exert asymmetric induction using chiral iron catalysts and that both an iron-nitrenoid and carbocation species may be reactive intermediates.
A visible-light-enabled
catalytic formylation of fluoroalkyl imines
is developed. With readily accessible starting materials and organocatalysts,
this method provides a general approach to masked fluoroalkyl amino
aldehydes. A synergistic catalytic effect between the photosensitizer
and the H atom transfer agent was proven pivotal to this transformation.
After removing the mask, free aldehydes can be obtained and further
converted to various β-fluoroalkyl β-amino alcohols, which
are attractive building blocks in the synthesis of bioactive and pharmaceutical
compounds.
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