Ligand-Controlled Copper-Catalyzed Halo-Halodifluoromethylation of Alkenes and Alkynes Using Fluorinated Carboxylic Anhydrides.

Polyhalogenated molecules are often found as bioactive compounds in nature and are used as synthetic building blocks. Fluoroalkyl compounds hold promise for the development of novel pharmaceuticals and agrochemicals, as the introduction of fluoroalkyl groups is known to improve lipophilicity, membrane permeability, and metabolic stability. Three-component 1,2-halo-halodifluoromethylation reactions of alkenes are useful for their synthesis. However, general methods enabling the introduction of halodifluoromethyl (CF2X) and halogen (X') groups in the desired combination of X and X' are lacking. To address this gap, for the first time, we report a three-component halo-halodifluoromethylation of alkenes and alkynes using combinations of commercially available fluorinated carboxylic anhydrides ((CF2XCO)2O, X=Cl and Br) and alkali metal halides (X'=Cl and Br). In situ prepared fluorinated diacyl peroxides were identified as important intermediates, and the use of appropriate bipyridyl-based ligands and a copper catalyst was essential for achieving high product selectivity. The synthetic utility of the polyhalogenated products was demonstrated by exploiting differences in the reactivities of their C-X and C-X' bonds to achieve selective derivatization. Finally, the reaction mechanism and ligand effect were investigated using experimental and theoretical methods to provide important insights for the further development of catalytic reactions.

Kinetic Resolution of Racemic 2-Hydroxyamides Using a Diphenylacetyl Component as an Acyl Source and a Chiral Acyl-Transfer Catalyst.

Various optically active 2-hydroxyamide derivatives are produced based on the kinetic resolution of racemic 2-hydroxyamides with a diphenylacetyl component and (R)-benzotetramisole ((R)-BTM), a chiral acyl-transfer catalyst, via asymmetric esterification and acylation. It was revealed that a tertiary amide can be used with this novel protocol to achieve high selectivity (22 examples; s-value reaching over 250). The resulting chiral compounds could be transformed into other useful structures while maintaining their chirality.

Stereochemistry and Reactivity of the HPA-Imine Mannich Intermediate.

Homophthalic anhydride (HPA) typically reacts rapidly with benzalimines to afford the formal [4+2] adduct, a 1,2,3,4-tetrahydroisoquinolin-1-one-4-carboxylic acid. The stereochemical outcome of this reaction is consistent with an open transition state comprising an iminium species and enolized HPA, leading to a short-lived amino-anhydride intermediate. In the case of N-tert-butylbenzalimine, this Mannich-type intermediate, which would normally cyclize at low temperature to a single isomer of the delta-lactam, is intercepted by base treatment to afford beta-lactam products. A pathway featuring ketene formation followed by ring closure is implicated.

Poly(γ-benzyl-L-glutamate)-PEG-alendronate multivalent nanoparticles for bone targeting.

Hydroxyapatite (HAP), a highly specific component of bone tissue, is the main target in order to impart osteotropicity. Bone targeted nanoparticles can increase the strength of the interaction with HAP through multivalency and thus constitute a valuable strategy in the therapeutics of skeletal diseases. PBLG10k-b-PEG6k-alendronate nanoparticles (~ 75 nm) were prepared by a simple nanoprecipitation method. The calcium affinity (KCa(+2)=1.8 × 10(4)M(-1)) of these nanoparticles was evaluated using isothermal titration calorimetry. The multivalent interaction with HAP surfaces (KHAP) was studied by fluorescence and was estimated to be 1.1 × 10(10)M(-1), which is more than 4000 times stronger than the reported monovalent interaction between alendronate and HAP surfaces. Molecular modeling suggests that the number of binding sites available at the HAP surface is in large excess than what is required for the whole surface coverage by alendronate decorated nanoparticles. The lower calcium affinity of these nanoparticles than for HAP allows calcium bound nanoparticles to interact with HAP, which yields a deeper understanding of bone targeted carriers and could potentially improve their bone targeting properties.