Cohesion matters! The correlation between the conformational rigidity of the polyelectrolyte and the size and stability of the globular assembly is discussed in this review article. Some examples of models for the association of polyelectrolytes to globular assemblies are shown here.
Like pearls on a string , molecular building blocks have been preorganized and then interlinked on a surface (see STM images). In this way both the supramolecular self‐assembly of the reactants as well as the subsequent thermal activation to release the protecting group are controlled.
Ultrafast light‐induced processes in a series of π‐conjugated mono‐, bis‐, tris‐ and tetrakis(terpyridine) derivatives are investigated by femtosecond time‐resolved spectroscopy. Non‐exponential excited‐state dynamics involving singlet–triplet intersystem crossing are observed which span from picoseconds to nanoseconds (see figure).
Folding in the tides : Upon hybridization, pyrene molecules assemble through interstrand stacking interactions to form double‐stranded, helical structures. Structural organization of the pyrene molecules is an intrinsic property of the oligoaryl part and takes place independently of the sequence of the attached DNA. Pyrene helicity is most pronounced in a bi‐segmental chimera, in which a DNA stem is present only at one end of the pyrene section.
The right bicycle : A concise formal synthesis of platencin was based on an efficient oxygen‐mediated palladium‐catalyzed cycloalkenylation of 1 to form a bicyclo[3.2.1]octane, and a deoxygenative rearrangement of tosylhydrazone 2 to construct the bicyclo[2.2.2]octane 3 . The total yield of the core structure 4 of platencin was 17.5 % for 13 steps from a commercially available compound. Ts=p‐toluenesulfonyl, TBS=tert‐butyldimethylsilyl, Piv=pivaloyl.
It's as simple as that : An in situ prepared chiral catalyst from the commercially available compounds Ti(OiPr)4 and (R)‐binol catalyzes the highly enantioselective ring‐opening of meso‐aziridines 1 with anilines 2 and furnishes valuable chiral 1,2‐diamines 3 in high yields and up to 99 % ee.(R)‐binol=(R)‐2,2′‐dihydroxy‐1,1′‐binaphthyl.
Losing the grip : The synthesis of multivalent low‐molecular‐weight dendrons with lysine branching units coupled to disulfide‐linked spermine surface groups is described. It is furthermore demonstrated that the dendrons bind DNA with good affinity (see image), but are also able to release the DNA in a reductive environment.
Dynamic transformation : A racemization catalyst and the enzyme Candida antarctica lipase B (CALB) were combined in a one‐pot dynamic kinetic resolution (DKR) of primary amines, which were transformed to their corresponding amides in up to 95 % yield and >99 % ee. This chemoenzymatic DKR was also applied to the synthesis of norsertraline (see scheme).
Easily side‐tracked : A simple route to the paclitaxel side chain and its analogues is based on the (R)‐proline‐catalyzed addition of aldehydes to N‐(phenylmethylene)benzamides, followed by oxidation of the resulting protected α‐hydroxy‐β‐benzoylaminoaldehydes (92–99 % ee). Esterification of the subsequent phenylisoserine derivatives with baccatin III gives paclitaxel analogues (see scheme).
Easy and direct : Regioselective Mizoroki–Heck‐coupling reactions using heteroaromatic tosylates as electrophiles were achieved, thus providing direct and easy access to highly functionalized α‐heteroarylvinyl amides and ethers.
Minty green : Zr–zeolite beta (Zr‐beta) directs the one‐pot catalytic cascade transformation of citral to menthols with high diastereoselectivity. The solid catalyst, a bifunctional Ni/Zr‐beta or a composite Zr‐beta–Ni/MCM‐41 system, is easily recovered and reused in this green synthetic method (see figure).
Not to be confused : Cereulide is an emetic toxin produced by Bacillus cereus through an unusual non‐ribosomal peptide synthesis, whereas valinomycin, produced by Streptomyces fulvissimus, is a known antibiotic drug. Cereulide has a greater complexation ability with metal ions than valinomycin and also exhibits a K+‐ion‐selective ionophore property at lower concentrations than valinomycin.
Not blue but red‐brown : A [1]ferrocenophanium ion has been synthesized and isolated as a red‐brown crystalline salt, surprisingly different in color from characteristically blue‐green unstrained ferrocenium ions. Compared to the neutral iron(II) counterpart, the [1]ferrocenophanium ion displays a considerably higher ring tilt and an increased propensity for ring‐opening reactions.
