It′s complicated! Triterpene saponins are a structurally and biologically diverse class of glycoconjugates of triterpenes that are widely distributed in terrestrial plants and some marine organisms. Current synthesis of these complex glycoconjugates has been discussed, whereupon the stereocontrolled glycosylation, global protection/deprotection, and the total synthesis of four unusual triterpene saponins are highlighted.
Recycling of “green” solvents : Recycling of ionic liquids with high efficiency is of key importance on going from the laboratory‐scale to large‐scale industrial application of these solvents.
Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.
ReacTiO 2 ns for rings : Gold nanoparticles supported on TiO2 are used as a novel heterogeneous catalyst for the isomerization of epoxides to allylic alcohols by a concerted mechanism (see scheme). The reaction proceeds in high yields and the product selectivity is often remarkable.
Salty metal : In the suboxometallate Cs9InO4, metallic cesium columns (see picture; blue) lie next to ionic oxoindate(III) columns. The chemistry of the suboxides is thus expanded to structures containing complex anions.
High pressure under the spotlight : A new milliliter‐scale reactor is developed for using supercritical CO2 to perform continuous photo‐oxidation reactions. Changing from a traditional microliter‐scale batch reaction to 8 hours of reaction using the new reactor gives a 3000‐fold scale‐up of the oxidation of α‐terpinene (see picture).
Amino sulfonamide catalyst : A distal proton of the axially chiral amino sulfonamide (S)‐ 1 realized the opposite diastereoselectivity in Mannich and cross‐aldol reactions compared with that observed in proline‐catalyzed reactions. The reactions catalyzed by (S)‐ 1 proceeded smoothly to give the anti‐Mannich and syn‐aldol adducts in excellent enantioselectivity (see scheme).
The quaternary king : Azithromycin ( 1 ), which has improved pharmacological profiles compared with erythromycins, was the target of an enantioselective synthesis. All the stereogenic quaternary carbon centers were elaborated by a desymmetrization of 2‐substituted glycerols using a chiral imine/CuCl2 catalyst.
Positive discrimination : Chemo‐ and regioselective palladium‐catalyzed cycloetherification of allendiols, namely β,γ‐ and γ,δ‐allendiols, may occur by judicious choice of palladium‐catalyzed conditions owing to their potential ability to discriminate between both nucleophilic sites (see scheme).
The effect of carbon is subtle but sweet : The flexible C‐linkage in the newly synthesised C‐glycosyl mimetic, Manα(1,6)‐C‐ManαOPh allows OH? π bonding, both in the gas phase and in aqueous solution. This interaction is absent in the O‐linked disaccharide (see figure).
The next generation : The grafting of titanocene complexes on the surfaces of MCM‐41 and SBA‐15 led to a new generation of anticancer drugs, which are very active against human cancer cells.
Quick on the uptake : A multiscale theoretical method predicts that the gravimetric adsorption capacities of H2 in Li‐doped covalent organic frameworks based on the building blocks shown (Li violet, H white, B pink, C green, O red, Si yellow) can reach nearly 7 % at T=298 K and p=100 bar, suggesting that these Li‐doped materials are promising adsorbents for hydrogen storage.
Active ingredients : A model for the simplest hydrolysis reaction is applied to all stages of stepwise hydrolysis and condensation taking place during a sol–gel process. The picture shows the molecular structures of the transition states of the ammonia‐ (left) and OH?‐promoted (right) condensation reactions of two Si(OH)4 molecules, including an additional water molecule.
