Domino Staudinger/aza‐Wittig/Mannich Reaction: An Approach to Diversity of Di‐ and Tetrahydropyrrole Scaffolds

A highly efficient and selective domino reaction producing valuable di‐ and tetrahydropyrrole‐based skeletons from azidoethyl‐substituted CH‐acids and (thio)carbonyl compounds has been developed. By involving the additional functional groups in starting compounds into the domino reaction or postmodification of the primary reaction products, the simple construction of the pharmaceutically relevant three‐ and polycyclic azaheterocyclic scaffolds was demonstrated.     

Metal–Organic Frameworks: From Molecules/Metal Ions to Crystals to Superstructures

Metal–organic frameworks (MOFs) are among the most attractive porous materials known today, exhibiting very high surface areas, tuneable pore sizes and shapes, adjustable surface functionality, and flexible structures. Advances in the formation of MOF crystals, and in their subsequent assembly into more complex and/or composite superstructures, should expand the scope of these materials in many applications (e.g., drug delivery, chemical sensors, selective reactors and removal devices, etc.) and facilitate their integration onto surfaces and into devices. This Concept article aims to showcase recently developed synthetic strategies to control the one‐, two‐ and three‐dimensional (1‐, 2‐ and 3D) organisation of MOF crystals.     

Self‐Assembly of Polyaniline/Au Composites: From Nanotubes to Nanofibers

Summary: Polyaniline (PANI)/Au composite nanotubes and nanofibers are synthesized through a self‐assembly process in the presence of camphorsulfonic acid and hydrochloric acid, as dopants, respectively. The PANI/Au composites are characterized by FT‐IR, UV‐vis, and thermogravimetric analysis to verify the incorporation of the Au nanoparticles and determine the Au content. Structural characterization is performed using SEM, TEM and X‐ray diffraction. The presence of the Au nanoparticles results in an increased conductivity and improved crystallinity of the PANI. The self‐assembly method employed here is a simple and inexpensive route to synthesize multifunctional nanotubes and nanofibers and could be extended to prepare other inorganic nanoparticle/PANI composites.

TEM image of PANI/Au nanotubes.     

Derivatization of propene/methyloctadiene copolymers: A flexible approach to side‐chain‐functionalized polypropenes

The copolymerization of propene with 7‐methyl‐1,6‐octadiene (MOD) catalyzed by Cp*TiMe₃/B(C₆F₅)₃ ( A ) and rac‐C₂H₄(Ind)₂ZrCl₂/methylaluminoxane ( B ) in toluene under 1 bar propene gave copolymers with unsaturated side chains. Under these conditions, catalyst A produced copolymers with an atactic backbone structure of type 1 , with 3.5–19.6 mol % MOD incorporation and weight‐average molecular weight = 0.7–2.7 × 10⁵. Using catalyst B , copolymers 2 with 0.4–3.8 mol % MOD incorporation were prepared. The comonomer incorporation was a linear function of the feed ratio. The titanium catalyst A had a significantly higher affinity for MOD than the sterically more hindered zirconocene B . Postpolymerization modification of the side‐chain C?C bond allowed the facile introduction of a wide variety of functional groups. Epoxidation and especially ozonolysis of the C?C bond, to give ? CHO and ? COOH functionalized copolymers, proved to be very facile routes to functionalized polypropenes. According to monitoring by NMR, most of these transformations proceed in an essentially quantitative conversion. As an example of potential applications of such polymers, polypropenes with covalently attached dyes were prepared that are suitable for blending. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1484–1497, 2002     

Palladium‐Catalyzed/Norbornene‐Mediated CH Activation/ N‐Tosylhydrazone Insertion Reaction: A Route to Highly Functionalized Vinylarenes

A straightforward method for the synthesis of highly functionalized vinylarenes through palladium‐catalyzed, norbornene‐mediated C?H activation/carbene migratory insertion is described. Extension to a one‐pot procedure is also developed. Furthermore, this method can also be used to generate polysubstituted bicyclic molecules. The reaction proceeds under mild conditions to give the products in satisfactory yields using readily available starting materials. This is a Catellani–Lautens reaction that incorporates different types of coupling partners. Additionally, this reaction is the first to demonstrate the possibility of combining Pd‐catalyzed insertion of diazo compounds and Pd‐catalyzed C?H activation.