Dipolar aggregation : Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic‐interaction‐directed self‐assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π‐stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform.
π–π assisted : Photoinduced electron transfer from cofacial porphyrin dimers to electron acceptors is prominently accelerated, whereas the back electron transfer is decelerated, relative to the corresponding porphyrin monomer (see figure).
Tuning in : The reaction of halocyclopentane organometallic reagents can be tuned by the choice of metal (see scheme). Cyclopentylmagnesium bromide reduces aldehydes and ketones to the corresponding alcohols. However, in the presence of ZnCl2, normal Grignard addition to the ketones gives tertiary alcohols with complete diastereoselectivity. These protocols were used in the asymmetric synthesis of two medicinally important compounds.
A practical and sustainable chemical process for the synthesis of highly substituted aldol?lactol products was achieved for the first time through the asymmetric Barbas–List aldol (BLA) reaction of 2‐hydroxybenzaldehydes with acetone in the presence of a catalytic amount of trans‐4‐OH‐L ‐proline (see scheme).
Triethylamine hydroiodide crystals were formed during Sonogashira reactions; after complete reaction the solution retains a characteristic light color (see picture). Very sluggish Sonogashira reactions of electron‐enriched aryl diiodides have been carried out in high yield in an oxygen‐free, two‐chamber reaction system. The formation of triethylamine hydroiodide crystals was monitored to determine the completion of reaction.
PS, I love you! Novel mixed phosphole/thiophene π‐conjugated systems were synthesized and their electronic properties have been studied both experimentally by UV/Vis spectroscopy and electrochemistry and by theoretical calculations. Exploiting the chemistry of both P‐ and S‐heteroles allows the generation of a diverse range of novel ring‐fused benzophosphole–thiophene derivatives.
Lighting up new platinum anticancer complexes : Photoactivation of a platinum(IV) diazido anticancer complex in the presence of a derivative of imidazole, an important constituent of biomolecules, gives surprising photoproducts, including a tetrakis imidazole platinum(II) adduct (see figure), together with free azide, dioxygen and ammonia.
From imines to amines through catalysis by IrI complexes of a new type of P,N ligand (see scheme): This reaction affords the corresponding optically active amines with up to 98 % ee and has also been used with perfect stereoselectivity in the asymmetric synthesis of sertraline ( 1 ), an important antidepressant chiral drug.
Osmabenzenes can be easily synthesized from two η2‐coordinated olefin osmacycles in the presence of benzonitrile by means of facile hydrogen‐transfer conversions (see graphic). Mechanisms for the formation of osmabenzenes are proposed based on DFT calculations.
Do the twist : The reaction of in situ generated phosphinidenes with phosphaalkynes is a facile route to the new metal‐coordinated η3‐diphosphavinylcarbene 1 , which shows facile ligand‐exchange reactions and undergoes an unprecedented rearrangement that involves phosphinidene complex 2 and η3‐phosphaalkenylphosphinidene complex 3 , the 1,3 isomer of 1 .
Following the light: Photoredox catalysis along with aminocatalysis have proved to be the right combination for one of the most challenging asymmetric transformation in organic synthesis: the direct intermolecular α‐alkylation of aldehydes.
