Synthesis, characterization, and catalytic reactivity of a highly basic macrotricyclic aminopyridine

The synthesis methods, physicochemical and structural characteristics, and catalytic reactivity of new macrocyclic proton chelators, N,N',N'-tris(p-tolyl)azacalix[3](2,6)(4-pyrrolidinopyridine) and N,N',N'-tris(p-tolyl)azacalix[3](2,6)(4-piperidinopyridine), are studied. The introduction of pyrrolidino and piperidino groups into the pyridine unit enables the enhancement of the synergistic proton affinity of the cavity of the macrotricycle giving a high basicity (pK(BH+) = 28.1 and 27.1 in CD(3)CN), resulting in a catalytic activity for the Michael addition of nitromethane with α,β-unsaturated carbonyl compounds.     

Practical Stannylation of Allyl Acetates Catalyzed by Nickel with Bu3SnOMe

A practical and scalable nickel‐catalyzed allylic stannylation of allyl acetates with Bu₃SnOMe is described. A variety of acyclic and cyclic allyl acetates, even with base‐sensitive moieties, undergoes the stannylation by using NiBr₂/4,4′‐di‐tert‐butylbipyridine (dtbpy)/Mn catalyst system to afford highly functionalized allyl stannanes with excellent regioselectivity and yields. Furthermore, the scope of protocol is also extended by the reaction of propargyl acetates, giving rise to propargyl or allenyl stannanes. Additionally, a unique diastereoselectivity using the nickel catalyst different from the palladium was demonstrated for the stannylation of cyclic allyl acetates. In the reaction, inexpensive and stable nickel complexes, abundant reductant (Mn), and atom‐economical stannyl source were used.     

Preparation of poly(arylenediphosphine)s by palladium‐catalyzed polycondensation: Formation of polymer transition‐metal complexes and catalytic reactions

The palladium‐catalyzed polycondensation of aryl diiodides with 1,3‐bis(phenylphosphino)propane afforded poly(arylenediphosphine)s in good yields. Treatment of the polyphosphine with elemental sulfur and hydrogen peroxide efficiently converted the polyphosphine into poly(arylenediphosphine sulfide) and poly(arylenediphosphine oxide), respectively. Treatment of the polyphosphines with Pd(II) and Pt(II) yielded corresponding polymer‐metal complexes with high metal contents. Application of the polymer‐Pd complexes in homogeneous and heterogeneous aryl alkynylation and carbonylation was examined. The polymer‐Pd complexes showed good catalytic activity similar to that of the corresponding low molecular weight Pd complex, and reuse of the polymer catalysts was easily achieved. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2637–2647, 2002     

Intermolecular hydrophosphination of alkynes and related carbon[bond]carbon multiple bonds catalyzed by organoytterbiums

Intermolecular hydrophosphination of alkynes with diphenylphosphine is catalyzed by a Yb[bond]imine complex, [Yb(eta(2)-Ph(2)CNPh)(hmpa)(3)], to give alkenylphosphines and phosphine oxides after oxidative workup in good yields under mild conditions. This reaction is also applicable to various carbon[bond]carbon multiple bonds such as conjugated diynes and dienes, allenes, and styrene derivatives. Regio- and stereoselectivity and the scope and limitation of the present reaction clearly differ from those of the corresponding radical reaction. Instead, the reaction takes place through insertion of alkynes to a Yb[bond]PPh(2) species, followed by protonation. In fact, the Yb[bond]phosphido complex, [Yb(PPh(2))(2)(hmpa)(3)], is obtained from the imine complex and phosphine, which exhibits similar catalyst activity for the hydrophosphination. The empirical rate law is nu = k[catalyst](2) [alkyne](1)[phosphine](0) at least under the standard conditions.     

Effect of fluctuations on tunneling currents via fine tin particles

Tunnel junctions containing Sn particles inside the oxide barrier have been prepared. Tunneling currents via these particles are measured. Interpretation is given in terms of the effect of fluctuations on the tunneling density of states in a “zero-dimensional” superconductor.     

Preparation of polythioamides from dialdehydes and diamines with sulfur by the Willgerodt–Kindler type reaction

Willgerodt–Kindler type reactions of dialdehydes and diamines in the presence of sulfur were investigated for preparation of polythioamides. The one‐pot, three‐component polycondensation afforded various polythioamides in moderate to good yields. The appropriate reaction conditions were examined for the separate monomers. The results led us to the proposed mechanism for the polycondensation including formation of the intermediate Schiff base polymers followed by the successive nucleophilic attack of polysulfide anions to the azomethine units to give the thioamide groups. Structure, solubility, and thermal properties of the polythioamides were also compared with those of analogous polyamides. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3739–3750, 2001     

Copper‐Catalyzed Three‐Component Borylstannylation of Alkynes

Regio‐ and stereoselective installation of boryl and stannyl moieties into a carbon–carbon triple bond of various alkynes has been achieved based on a three‐component coupling reaction by using a diboron and a tin alkoxide with the aid of a copper(II) acetate–tricyclohexylphosphine complex, giving diverse vic‐borylstannylalkenes in a straightforward manner. Carbon–tin and carbon–boron bonds of the resulting borylstannylation product are successively transformed into carbon–carbon bonds by a Migita–Kosugi–Stille and a Suzuki–Miyaura coupling, leading to the formation of (Z)‐tamoxifen with anti‐breast cancer activity.