Various practical methods for the selective C-H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing-group-assisted para C-H functionalization of toluene derivatives, we herein report the first remote para C-H functionalization of phenol derivatives by using a recyclable silicon-containing biphenyl-based template. The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol-based natural products.
Strong
σ-coordination by a heteroatom containing directing
group (DG) is one of the effective strategies for performing site-selective
C–H functionalization. Despite tremendous progress in directed ortho-C–H functionalization, selective meta-C–H functionalization using strong σ-coordination remains
extremely challenging. Herein, we introduce the 8-nitroquinoline-based
DG to ensure the formation of a stable palladacycle which enables
selective meta-alkenylation and acetoxylation of
arenes. Kinetic experiments, ESI-MS, NMR, and DFT studies provided
important information regarding the mechanism of the reaction. The
scalability as well as diversification of the products have been examined
and are expected to be beneficial in pharmaceutical and material sciences.
Controlling sophisticated motion by molecular motors is am ajor goal on the road to future actuators and soft robotics.T aking inspiration from biological motility and mechanical functions common to artificial machines,r esponsive small molecules have been used to achieve macroscopic effects,however,translating molecular movement along length scales to precisely defined linear,t wisting and rotary motions remain particularly challenging.H ere,w ep resent the design, synthesis and functioning of liquid-crystal network (LCN) materials with intrinsic rotary motors that allow the conversion of light energy into reversible helical motion. In this responsive system the photochemical-driven molecular motor has ad ual function operating both as chiral dopant and unidirectional rotor amplifying molecular motion into ac ontrolled and reversible left-or right-handed macroscopic twisting movement. By exploiting the dynamic chirality,d irectionality of motion and shape change of as ingle motor embedded in an LC-network, complex mechanical motions including bending, walking and helical motion, in soft polymer materials are achieved which offers fascinating opportunities toward inherently photo-responsive materials.
Photolabile Protecting Groups (PPGs) are molecular tools used, for example, in photopharmacology for the activation of drugs with light, enabling spatiotemporal control over their potency. Yet, red‐shifting of PPG activation wavelengths into the NIR range, which penetrates the deepest in tissue, has often yielded inefficient or insoluble molecules, hindering the use of PPGs in the clinic. To solve this problem, we report herein a novel concept in PPG design, by transforming clinically‐applied NIR‐dyes with suitable molecular orbital configurations into new NIR‐PPGs using computational approaches. Using this method, we demonstrate how Cy7, a class of NIR dyes possessing ideal properties (NIR‐absorption, high molecular absorptivity, excellent aqueous solubility) can be successfully converted into Cy7‐PPG. We report a facile synthesis towards Cy7‐PPG from accessible precursors and confirm its excellent properties as the most redshifted oxygen‐independent NIR‐PPG to date (λmax=746 nm).
This discovery illustrates selective meta C-H bond activation from multiple non-equivalent C-H bonds present in medicinally relevant arylethanesulfonic acid and the 2-arylpropanoic acid moiety using weakly coordinating nitrile as a directing group. Transformation of the meta olefinated compounds to important organic molecules has been demonstrated. Efforts were made to obtain mechanistic detail of the meta C-H bond functionalization reaction.
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