560 research outputs found
The Role of Nest Location on the Reproductive Success of Piping Plovers Breeding at Rockaway Beach, New York
The studyâs goal was to learn what aspects of the piping plover experience affect reproductive outcomes at Rockaway Beach Endangered Species Nesting Area. Nest location was found to help predict reproductive success. Nests further from American oystercatcher nests were likely to fledge more chicks. Reproductive success was low in 2021
Platinum and Palladium Complexes Containing Cationic Ligands as Catalysts for Arene H/D Exchange and Oxidation
No AbstractPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77957/1/ange_201002351_sm_miscellaneous_information.pd
Anthropogenic reaction parameters - the missing link between chemical intuition and the available chemical space
How do skilled synthetic chemists develop
such a good intuitive expertise
?
Why can we
only access such a small amount of the available chemical space
â
both in terms of the
re
actions used and the chemical scaffolds we make?
We argue here that these
seemingly
unrelated
questions
have a common root and
are strongly
interdependent
.
We performed a
comprehensive analysis of organic reaction parameters dating back to 1771 and discove
red
that
there are several
anthropogenic
factors
that limit the
reaction parameters and thus the
scop
e of synthetic
chemistry.
Nevertheless,
many of the anthropogenic limitations such as
the
narrow parameter space and the opportunity of the rapid and clear
feedback on the progress of
reactions appear to be crucial for the acquisition of valid and reliable chemical intuition.
In
parallel, however, all of these
same
factors represent limitations
for the
exploration of
available chemistry space and
we argue
th
at these
are thus at least partly responsible for
limited access to new chemistries. We advocate, therefore, that the present
anthropogenic
boundaries can be expanded by a more conscious expl
oration of âoff
-
roadâ chemistry that
would also
extend the intuit
ive knowledge of trained chemists
Increasing Catalyst Efficiency in CâH Activation Catalysis
CâH activation reactions with high catalyst turnover numbers are still very rare in the literature and 10 mol % is a common catalyst loading in this field. We offer a representative overview of efficient CâH activation catalysis to highlight this neglected aspect of catalysis development and inspire future effort towards more efficient CâH activation. Examples ranging from palladium catalysis, Cp*Rh III - and Cp*Co III -catalysis, the CâH borylation and silylation to methane CâH activation are presented. In these reactions, up to tens of thousands of catalyst turnovers have been observed
Photochemical CâH activation: generation of indole and carbazole libraries, and first total synthesis of clausenawalline D
The photolysis of N-aryltriazoles and N-arylbenzotriazoles leads to indoles and carbazoles, respectively. Because libraries of triazoles can be accessed rapidly, for example by the copper-catalyzed [3+2] cycloaddition reaction between alkynes and azides, this reaction allows the preparation of indoles in a single operation, by the simultaneous photolysis of the precursor library. As an example of such a synthesis of carbazoles, we prepared for the first time clausenawalline D, an antimalarial alkaloid that was recently isolated
S,O-ligand-promoted palladium-catalyzed C-H olefination of arenes with allylic substrates
An efficient catalytic system for the CâH olefination of arenes with different allylic substrates is reported. The catalytic system is based on Pd(OAc)2 and a readily accessible bidentate S,O-ligand. The methodology shows high activity with a wide range of arenes, including bulky and, electron-rich and -poor arenes. The applicability of this catalyst is demonstrated in the late-stage functionalization of the complex molecule O-methylestrone
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