3 research outputs found
Light-Mediated Reductive Debromination of Unactivated Alkyl and Aryl Bromides
Cleavage
of carbon–halogen bonds via either single-electron reduction
or atom transfer is a powerful transformation in the construction
of complex molecules. In particular, mild, selective hydrodehalogenations
provide an excellent follow-up to the application of halogen atoms
as directing groups or the utilization of atom transfer radical addition
(ATRA) chemistry for the production of hydrocarbons. Here we combine
the mechanistic properties of photoredox catalysis and silane-mediated
atom transfer chemistry to accomplish the hydrodebromination of carbon–bromide
bonds. The resulting method is performed under visible light irradiation
in an open vessel and is capable of the efficient reduction of a variety
of unactivated alkyl and aryl substrates
Microwave-Assisted Synthesis of Heteroleptic Ir(III)<sup>+</sup> Polypyridyl Complexes
We
report a rapid, one-pot, operationally simple, and scalable
preparation of valuable cationic heteroleptic iridiumÂ(III) polypyridyl
photosensitizers. This method takes advantage of two consecutive microwave
irradiation steps in the same reactor vial, avoiding the need for
additional reaction purifications. A number of known heteroleptic
iridiumÂ(III) complexes are prepared in up to 96% yield. Notably, this
method is demonstrated to provide the synthetically versatile photosensitizer
[IrÂ(ppy)<sub>2</sub>(dtbbpy)]ÂPF<sub>6</sub> in >1 g quantities
in
less than 5 h of bench time. We envision this method will help accelerate
future developments in visible-light-dependent chemistry
Mechanistic Investigations of the Iron(III)-Catalyzed Carbonyl-Olefin Metathesis Reaction
IronÂ(III)-catalyzed
carbonyl-olefin ring-closing metathesis represents
a new approach toward the assembly of molecules traditionally generated
by olefin–olefin metathesis or olefination. Herein, we report
detailed synthetic, spectroscopic, kinetic, and computational studies
to determine the mechanistic features imparted by ironÂ(III), substrate,
and temperature to the catalytic cycle. These data are consistent
with an ironÂ(III)-mediated asynchronous, concerted [2+2]-cycloaddition
to form an intermediate oxetane as the turnover-limiting step. Fragmentation
of the oxetane via Lewis acid-activation results in the formation
of five- and six-membered unsaturated carbocycles