Ruthenium(II)-Catalyzed Alkene C–H Bond Functionalization on Cinnamic Acids: A Facile Synthesis of Versatile α‑Pyrones

An inexpensive ruthenium­(II) complex enabled oxidative annulation of alkynes by using cinnamic acid derivatives to provide diversely decorated multisubstituted α-pyrones

Carbon–Carbon Bond Cleavage Reaction: Synthesis of Multisubstituted Pyrazolo[1,5‑<i>a</i>]pyrimidines

A new carbon–carbon bond cleavage reaction was developed for the efficient synthesis of multisubstituted pyrazolo­[1,5-<i>a</i>]­pyrimidines. This base induced reaction of 1,3,5-trisubstituted pentane-1,5-diones and substituted pyrazoles afforded good yields of the pyrazolo­[1,5-<i>a</i>]­pyrimidines

Hydroxyl-Directed Ru(II)-Catalyzed Synthesis of Fused Dihydrofurans Using 1,4-Dioxane and Sulfoxonium Ylides as Annulating Agents

An unprecedented annulation reaction is developed for the synthesis of dihydrofuran-fused compounds. In this Ru-catalyzed hydroxyl-group-directed reaction, easily affordable sulfoxonium ylides and 1,4-dioxane were used as the annulating partners. This is the first example of the use of 1,4-dioxane as a methylene source to construct a heterocyclic scaffold. A wide range of dihydrofuran0fused coumarins and naphthalenes were synthesized using this three-component reaction

Ru(II)-Catalyzed and Ligand-Controlled C–H Activation and Annulation via 1,2-Phenyl Shift: Synthesis of Quaternary Carbon-Centered Pyrimidoindolones

A novel Ru­(II)-catalyzed C–H activation and annulation reaction of <i>N</i>-arylpyrazol-5-ones and diaryl/arylalkyl-substituted alkynes is developed. Unlike the reported metal-catalyzed C–H activation and annulation reactions, in the present bidentate amine-ligand controlled C–H activation and annulation reaction, the annulation occurs via a 1,2-aryl shift to afford quaternary carbon-centered pyrimidoindolones

Ru(II)-Catalyzed C–H Activation and Annulation Reaction via Carbon–Carbon Triple Bond Cleavage

An unprecedented Ru­(II)-catalyzed C–H activation and annulation reaction, which proceeds via C–C triple bond cleavage, is reported. This reaction of 2-phenyl­dihydro­phthalazine­diones with alkynes, which works most efficiently in the presence of bidented ligand 1,3-bis­(diphenylphosphino)­propane, affords good yields of substituted quinazolines

Novel Bivalent Ligands for D2/D3 Dopamine Receptors: Significant Cooperative Gain in D2 Affinity and Potency

This report describes development of a series of novel bivalent molecules with a pharmacophore derived from the D2/D3 agonist 5-OH-DPAT. The spacer length in the bivalent compounds had a pronounced influence on affinity for D2 receptors. A 23-fold increase of D2 affinity was observed at a spacer length of 9 or 10 (compounds <b>11d</b> and <b>14b</b>) as compared to monovalent 5-OH-DPAT (<i>K</i>_i; 2.5 and 2.0 vs 59 nM for <b>11d</b> and <b>14b</b> vs 5-OH-DPAT, respectively). The functional potency of <b>11d</b> and <b>14b</b> indicated a 24- and 94-fold increase in potency at the D2 receptor as compared to 5-OH-DPAT (EC₅₀; 1.7 and 0.44 vs 41 nM for <b>11d</b> and <b>14b</b> vs 5-OH-DPAT, respectively). These are the most potent bivalent agonists for the D2 receptor known to date. This synergism is consonant with cooperative interaction at the two orthosteric binding sites in the homodimeric receptor