An Accelerated Modular-Orthogonal Ni-Catalyzed Methodology to Symmetric and Nonsymmetric Constitutional Isomeric AB2 to AB9 Dendrons Exhibiting Unprecedented Self-Organizing Principles.

Five libraries of natural and synthetic phenolic acids containing five AB3, ten constitutional isomeric AB2, one AB4, and one AB5 were previously synthesized and reported by our laboratory in 5 to 11 steps. They were employed to construct seven libraries of self-assembling dendrons, by divergent generational, deconstruction, and combined approaches, enabling the discovery of a diversity of supramolecular assemblies including Frank-Kasper phases, soft quasicrystals, and complex helical organizations, some undergoing deracemization in the crystal state. However, higher substitution patterns within a single dendron were not accessible. Here we report three libraries consisting of 30 symmetric and nonsymmetric constitutional isomeric phenolic acids with unprecedented sequenced patterns, including two AB2, three AB3, eight AB4, five AB5, six AB6, three AB7, two AB8, and one AB9 synthesized by accelerated modular-orthogonal Ni-catalyzed borylation and cross-coupling. A single etherification step with 4-(n-dodecyloxy)benzyl chloride transformed all these phenolic acids, of interest also for other applications, into self-assembling dendrons. Despite this synthetic simplicity, they led to a diversity of unprecedented self-organizing principles: lamellar structures of interest for biological membrane mimics, helical columnar assemblies from rigid-solid angle dendrons forming Tobacco Mosaic Virus-like assemblies, columnar organizations from adaptable-solid angle dendrons forming disordered micellar-like nonhelical columns, columns from supramolecular spheres, five body-centered cubic phases displaying supramolecular orientational memory, rarely encountered in previous libraries forming predominantly Frank-Kasper phases, and two Frank-Kasper phases. Lessons from these self-organizing principles, discovered within a single generation of self-assembling dendrons, may help elaborate design principles for complex helical and nonhelical organizations of synthetic and biological matter.

Aliphatic Polyethers with Sulfate, Carboxylate, and Hydroxyl Side Groups-Do They Show Anticoagulant Properties?

There is increasing interest in the synthesis of low molecular weight heparin and heparan sulfate mimetic polymers because of their various potential biomedical applications. The functional activity of heparin and heparan sulfate is believed to arise from the presence of a number of functional groups, such as hydroxyl, carboxylate and sulfate groups. The design and synthesis of novel heparin-mimetic polymers with a particular functionality poses a formidable challenge and requires carefully control of the selective conversion of functional groups on the polymer chain. Here, this study describes a simple and efficient synthetic protocol for the preparation of heparin-mimetic linear polyglycidol copolymers based on the selective conversion of primary hydroxyl groups to carboxylic acids under ruthenium-catalyzed selective dehydrogenation in basic aqueous solution. To achieve the anticoagulant activity of these polymers, primary hydroxyl groups are selectively converted to sulfate groups. The anticoagulant activity of the heparin mimics is studied by rotational thromboelastometry using EXTEM and INTEM assays. The environmentally benign process described herein provides an attractive route for the synthesis of heparin-mimetic polymers with tailored functions such as anticoagulant activity.

A green and sustainable phosphine-free NHC-ruthenium catalyst for selective oxidation of alcohols to carboxylic acids in water.

In this work, we present a new catalytic system for the selective dehydrogenative oxidation of primary alcohols to carboxylic acids using a phosphine-free NHC-ruthenium catalyst in water under mild reaction conditions. With this catalytic system, a variety of primary alcohols have been converted to carboxylic acids respectively, in aqueous media, without using any additional oxidant; the only side product in this reaction is molecular hydrogen. This novel synthetic protocol is applied for direct oxidation of biologically active monosaccharides and polymers with primary alcohol groups in the side chain. The use of water as a solvent and oxygen donor as well as the absence of any toxic oxidizing agent make this atom economical reaction interesting from an environmental point of view.

An efficient N-heterocyclic carbene-ruthenium complex: application towards the synthesis of polyesters and polyamides.

The ruthenium benzimidazolylidene-based N-heterocyclic carbene (NHC) complex 4 catalyzes the direct dehydrogenative condensation of primary alcohols into esters and primary alcohols in the presence of amines to the corresponding amides in high yields. This efficient new catalytic system shows a high selectivity towards the conversion of diols to polyesters and of a mixture of diols and diamines to polyamides. The only side product formed in this reaction is molecular hydrogen. Remarkable is the conversion of hydroxytelechelic polytetrahydrofuran (Mn = 1000 g mol(-1))--a polydispers starting material--into a hydrolytically degradable polyether with ester linkages (Mn = 32 600 g mol(-1)) and, in the presence of aliphatic diamines, into a polyether with amide linkages in the back bone (Mn = 16 000 g mol(-1) ).