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In this paper, we have studied the chiroptical properties of a family of o-oligo(phenyleneethynylene) ( o-OPE) derivatives with different steric hindrance. Experimental results show high dissymmetry factors (gabs and glum up to 1.1 × 10−2) and very similar electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) for all the derivatives that make this basic o-OPE scaffold a robust pure organic emitter. Vibrational circular dichroism spectra are used to characterize conformational properties in solution. Density functional theory and time-dependent density functional theory calculations support experimental results also proving that ECD and CPL are almost exclusively linked to helical moiety and not to size or conformation of substituents. As chiroptical properties of these emitters are independent of substituents, this OPE scaffold can be used as basic skeleton for the design of sensing probes with high CPL efficiencies. [ABSTRACT FROM AUTHOR]

Smallmolecular probes able to act as sensors are of enormous interestthanks to their multiple applications. Here, we report on the developmentof a novel supramolecular dual viscosity and polarity probe basedon the foldamer concept, which increases the resolution limits oftraditional probes at low viscosity values (0–4 mPa·s).The applicability of this new probe has been tested with a supramolecularorganogel. [ABSTRACT FROM AUTHOR]

A straightforward access to polyhydroxylated terpenoids based on two key titanocene(III)-mediated reactions is presented: the 'head-to-tail' Barbier-type addition of prenyl chlorides to α,β-unsaturated aldehydes, which allows the introduction of hydroxy groups at desirable positions of the acyclic precursor, and the subsequent bioinspired radical cyclisation. This methodology has been also used in the first total synthesis of pentacyclic sesterstatin 1 and a model compound of the C-D rings of aspergilloxide. [ABSTRACT FROM AUTHOR]

A mild method for the selective esterification of primary alcohols is described. The use of different phosphines, I2, and imidazole allows the selective esterification of a wide variety of acids with excellent results. The generation of a bulky phosphonium-carboxylate salt as intermediate could justify the selectivity observed in this process. Additionally, amides also can be synthesized with use of this method. [ABSTRACT FROM AUTHOR]

Review: 154 refs. [ABSTRACT FROM AUTHOR]

A new family of chiral saddle-helix hybrid nanographenes is reported. The first hexa-peri-hexabenzocoronene (HBC) analogues bearing a nine-membered carbocycle are presented. Furthermore, for the first time, π-extended carbo[n]helicenes containing a nine-membered ring as part of the helical moiety have been synthesized. The combination of a [5]helicene moiety and a nonagon ring in a single chiral motif induces a tremendous distortion from planarity into the nanographenic structures compared to other saddle-helix hybrids such as heptagon- and octagon-containing π-extended carbo[5]helicenes. In fact, the interplanar angle of the two terminal rings reaches the largest angle (134.8°) of a carbohelicene reported to date, thus being by far the most twisted helicene yet prepared. Photophysical properties evaluation showed improved absorption dissymmetry factors (|g abs |=4.2×10 -3 ) in the new family of nonagon-containing π-extended carbo[5]helicenes., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Just as "Deconstructivism" appeared as a novel movement in architecture in the 1980s, deconstructive approaches have recently emerged as excellent strategies for scaffold hopping modifications in chemistry. The deconstruction and functionalization of cyclic molecules mainly involves the cleavage of the carbon-carbon (C-C) bond followed by the construction of new bonds. The cleavage of inert C-C single bonds, especially in unstrained cycles, and their subsequent functionalization is still one of the most sought-after challenges in chemistry. In this vein, radical-mediated strategies provide an excellent approach for achieving this aim. This minireview is an outline of the history of homolytic cleavage and highlights the recent advances in exploring new chemical space by deconstructive functionalization., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In recent years, hydroxylamines derivatives have been exploited as nitrogen-radical precursors in visible-light photochemistry. Their ability to serve as electrophores in redox chemistry has propelled the development of many novel transformations. Fundamental mechanistic aspects as well as the importance in the preparation of nitrogen-containing molecules will be highlighted., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A photoinduced cascade strategy leading to a variety of differentially functionalised nitriles and ketones has been developed. These reactions rely on the oxidative generation of iminyl radicals from simple oximes. Radical transposition by C(sp 3 )-(sp 3 ) and C(sp 3 )-H bond cleavage gives access to distal carbon radicals that undergo S H 2 functionalisations. These mild, visible-light-mediated procedures can be used for remote fluorination, chlorination, and azidation, and were applied to the modification of bioactive and structurally complex molecules., (© 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

An efficient synthesis of polysubstituted 2-alkenylfurans using Ca(NTf 2 ) 2 /KPF 6 as a catalytic mixture is described. It is based on the cycloelimination of readily available propargyl alcohols tethered to β-keto esters under dry conditions to avoid competitive Meyer-Schuster rearrangement. The furan can be further functionalized in situ by a calcium-catalyzed Friedel-Crafts-type reaction with secondary and tertiary alcohols. The title reaction allows for the high-yielding preparation of di-, tri-, and tetrasubstituted 2-alkenylfurans, which are important subunits of bioactive compounds., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A straightforward access to polyhydroxylated terpenoids based on two key titanocene(III)-mediated reactions is presented: the "head-to-tail" Barbier-type addition of prenyl chlorides to α,β-unsaturated aldehydes, which allows the introduction of hydroxy groups at desirable positions of the acyclic precursor, and the subsequent bioinspired radical cyclisation. This methodology has been also used in the first total synthesis of pentacyclic sesterstatin 1 and a model compound of the C-D rings of aspergilloxide., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)