Herein we describe a mild method for the dual C(sp )-H bond functionalization of saturated nitrogen-containing heterocycles through a sequential visible-light photocatalyzed dehydrogenation/[2+2] cycloaddition procedure. As a complementary approach to the well-established use of iminium ion and α-amino radical intermediates, the elusive cyclic enamine intermediates were effectively generated by photoredox catalysis under mild conditions and efficiently captured by acetylene esters to form a wide array of bicyclic amino acid derivatives, thus enabling the simultaneous functionalization of two vicinal C(sp )-H bonds.
Herein, we report a general strategy for the rational design of an efficient organic photocatalyst, and we describe a robust method for the direct C(sp 3 )−H carbamoylation of saturated aza-heterocycles under mild conditions by using a naphthalimide (NI)-based organic photocatalyst. This protocol provides a concise and practical approach for the rapid installation of a valuable amide bond onto pharmaceutically useful saturated aza-heterocycles to access a wide range of cyclic α-amino amides. A series of mechanism investigations have demonstrated this transformation undergoes a visible-light photocatalytic, oxidative Ugi reaction process.
Herein, we describe
a novel and efficient method for constructing
a series of fluorine-containing γ-keto acid derivatives through
combining visible-light photoredox catalysis and chiral Lewis acid
catalysis. With this dual catalytic strategy, a variety of chiral
γ-keto amides containing a gem-difluoroalkyl
group and a series of fluorine-containing α,β-unsaturated-γ-keto
esters were successfully constructed with high stereoselectivities,
respectively. A series of experiments showed that the chemoselectivity
of this process was highly dependent on the fluorine reagents besides
the Lewis acid catalysts. This approach facilitates rapid access to
γ-keto acid derivatives, an important class of precursors for
pharmaceuticals, plasticizers, and various other additives.
Carbocation rearrangement reactions are of great significance to synthetic and biosynthetic chemistry. In pursuit of a scale of inherent migratory aptitude that takes into account dynamic effects, both uphill and downhill ab initio molecular dynamics (AIMD) simulations were used to examine competing migration events in a model system designed to remove steric and electronic biases. The results of these simulations were combined with detailed investigations of potential energy surface topography and variational transition state theory calculations to reveal the importance of nonstatistical dynamic effects on migratory aptitude.
A series of inexpensive, easily tunable, and highly reducing organic photocatalysts (PCs) that exhibit strong absorption in the visible region are described. Time-dependent density functional theory calculations were applied to corroborate the experimental observations and explain the relationship between the structure and property. The photocatalytic efficiency of these PCs was demonstrated by catalyzing several challenging reactions and the radical cascade cyclization of 1,6-diyne with superior photocatalytic efficiency to other organic photocatalysts.
A selectivity model based on the widths of pathways to competing products, rather than barrier heights, is formulated for the butadiene + allyl cation reaction. This model was arrived at...
Accurate size analysis of nanoparticles
(NPs) is vital for nanotechnology.
However, this cannot be realized based on conventional single-nanoparticle
collision (SNC) because the current intensity, a thermodynamic parameter
of SNC for sizing NPs, is always smaller than the theoretical value
due to the effect of NP movements on the electrode surface. Herein,
a size-dependent dynamic parameter of SNC, current lifetime, which
refers to the time that the current intensity decays to 1/e of the
original value, was originally utilized to distinguish differently
sized NPs. Results showed that the current lifetime increased with
NP size. After taking the current lifetime into account rather than
the current intensity, the overlap rates for the peak-type current
transients of differently sized Pt NPs (10 and 15 nm) and Au NPs (18
and 35 nm) reduced from 73 and 7% to 45 and 0%, respectively, which
were closer to the theoretical values (29 and 0%). Hence, the proposed
SNC dynamics-based method holds great potential for developing reliable
electrochemical approaches to evaluate NP sizes accurately.
The selective C-C bond deconstruction/refunctionalization via a photoredox/nickel dual-catalyzed hydroalkylation of alkynes is developed under mild reaction conditions. In this protocol, a broad range of alkyl- and aryl-alkynes could react...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.