Highly regioselective cyclotrimerization of 1-perfluoroalkylenynes catalyzed by nickel.

We report the highly regioselective cyclotrimerization of the 1-perfluoroalkylenynes in the presence of Ni(PPh3)4. The substituent effects on the reactivity of the enynes were investigated. We also succeeded in the nickel-catalyzed cocyclization of the 1-perfluoroalkylenynes with (trimethylsilyl)-acetylene. The possible structures of the intermediates of the cyclotrimerization and the reasons for the observed high regioselectivity were discussed.     

Reactions of acetonitrile coordinated to a nitrosylruthenium complex with H2O or CH(3)OH under mild conditions: structural characterization of imido-type complexes

The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) (bpy = 2,2'-bipyridine) in H(2)O at room temperature proceeded to afford two new nitrosylruthenium complexes. These complexes have been identified as nitrosylruthenium complexes containing the N-bound methylcarboxyimidato ligand, cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+), and methylcarboxyimido acid ligand, cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+), formed by an electrophilic reaction at the nitrile carbon of the acetonitrile coordinated to the ruthenium ion. The X-ray structure analysis on a single crystal obtained from CH(3)CN-H(2)O solution of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](PF(6))(3) has been performed: C(22)H(20.5)N(6)O(2)P(2.5)F(15)Ru, orthorhombic, Pccn, a = 15.966(1) A, b = 31.839(1) A, c = 11.707(1) A, V = 5950.8(4) A(3), and Z = 8. The structural results revealed that the single crystal consisted of 1:1 mixture of cis-[Ru(NO)(NH=C(O)CH(3))(bpy)(2)](2+) and cis-[Ru(NO)(NH=C(OH)CH(3))(bpy)(2)](3+) and the structural formula of this single crystal was thus [Ru(NO)(NH=C(OH(0.5))CH(3))(bpy)(2)](PF(6))(2.5). The reaction of cis-[Ru(NO)(CH(3)CN)(bpy)(2)](3+) in dry CH(3)OH-CH(3)CN at room temperature afforded a nitrosylruthenium complex containing the methyl methylcarboxyimidate ligand, cis-[Ru(NO)(NH=C(OCH(3))CH(3))(bpy)(2)](3+). The structure has been determined by X-ray structure analysis: C(25)H(29)N(8)O(18)Cl(3)Ru, monoclinic, P2(1)/c, a = 13.129(1) A, b = 17.053(1) A, c = 15.711(1) A, beta = 90.876(5) degrees, V = 3517.3(4) A(3), and Z = 4.     

Asymmetric synthesis of the carbon-14-labeled selective glucocorticoid receptor modulator using cinchona alkaloid catalyzed addition of 6-bromoindole to ethyl trifluoropyruvate

We describe in this study the asymmetric synthesis of radioisotope (RI)-labeled selective glucocorticoid receptor modulator. This synthesis is based on optimization of the cinchona alkaloid catalyzed addition of 6-bromoindole to ethyl trifluoropyruvate and Negishi coupling of zinc cyanide to the 6-bromoindole moiety. [1?C] Labeled (-)-{4-[(1-{2-[6-cyano-1-(cyclohexylmethyl)-1H-indol-3-yl]-3,3,3-trifluoro-2-hydroxypropyl}piperidin-4-yl)oxy]-3-methoxyphenyl}acetic acid (-)-1 was synthesized successfully with high enantioselectivity (>99% ee) and sufficient radiochemical purity.     

Synthesis of cyclophanes via an intermolecular Pd-catalyzed enyne-diyne cross-benzannulation approach

Several novel types of cyclophanes were efficiently synthesized via an intermolecular palladium-catalyzed cross-benzannulation of cyclic enynes and diynes. These types of cyclophanes are not accessible through an intramolecular mode of the homo-benzannulation protocol, reported previously. Cyclic reactants (enynes and diynes) were readily prepared in reasonable yields from commercially available materials using known procedures. The fact that the cyclic Z-enyne 29, in contrast to its E-counterpart, underwent benzannulation to produce the cyclophane 28 brought additional support for the necessity of having an E-hydrogen atom at the terminal olefin moiety of nonactivated enynes, which was found previously in the benzannulation of the acyclic substrates.     

Enhanced reactivity of electron-deficient enynes in the palladium-catalyzed homo-benzannulation of conjugated enynes

We report the high reactivity of electron-deficient enynes in the homo-benzannulation of conjugated enynes in the presence of Pd(PPh3)4. The introduction of electron-withdrawing groups enabled us to carry out the benzannulation of 1-substituted enynes as well as 1,2- and 2,4-disubstituted enynes. Polysubstituted benzenes were prepared in a highly regioselective manner in good to excellent yields.