Geometrically pure, all-cis poly(phenylene vinylenes) (PPVs) are synthesized by Suzuki-Miyaura-type polycondensation of 2,5-dioctyloxy-1,4-benzenediboronic acid with (Z,Z)-bis(2-bromoethenyl)benzenes, which are prepared by ruthenium-catalyzed (Z)-selective double hydrosilylation of diethynylbenzenes, followed by bromodesilylation of the resulting (Z,Z)-bis(2-silylethenyl)benzenes with N-bromosuccinimide. The all-cis PPVs thus obtained undergo one-way photoisomerization to the corresponding trans-PPVs both in solution and in the solid. This phenomenon is applied to direct microscale patterning of PPVs onto a quartz substrate.

Fischer‐type ruthenium carbene complexes bearing a selanylcarbene ligand efficiently catalyze ring‐opening/cross‐metathesis (ROCM) of norbornene derivatives with phenyl vinyl selenide to give the ROCM products in high selectivities (see scheme).

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A highly stereocontrolled synthesis of five kinds of cis-poly[(arylenevinylene)-alt-(2,5-dioctyloxy-1,4-phenylenevinylene)]s has been accomplished by Suzuki−Miyaura-type polycondensation [arylene = p-phenylene (3af), m-phenylene (3bf), 4,4‘-biphenylene (3cf), 2,7-fluorenylene (3df), 9,9-dihexyl-2,7-fluorenylene (3ef)]. Reactions of (Z,Z)-bis(2-bromoethenyl)arenes (1a − e) with 2,5-dioctyloxybenzene-1,4-diboronic acid (2fx) in toluene in the presence of Pd(PPh3)4 catalyst, aqueous KOH base, and Bu4NBr as a phase-transfer catalyst at 80 °C for 24 h form 3af − ef with number-average molecular weight (M n) of 5700−9500 in 77−99% yields. The stereoregularity of vinylene linkages in the polymer backbone has been found at least 95%. The starting monomers (1a − e) were prepared in almost geometrically pure forms (≥99% cis), either by ruthenium-catalyzed hydrosilylation of diethynylarenes followed by bromodesilylation of the resulting bis(2-bromoethenyl)arenes or by addition of bromine to arenediacrylic acids followed by debrominative decarboxylation promoted by Et3N. MALDI-TOF-MS analysis of cis-3af has revealed the presence of two types of polymers having different end groups. Type I polymer bears (Z)-4-(2-bromoethenyl)phenyl and 2,5-dioctyloxyphenyl group at each end, whereas type II polymer has 2,5-dioctyloxyphenyl groups at both ends. Type I polymer is successfully converted to type II polymer by palladium-catalyzed reaction with 2,5-dioctyloxybenzeneboronic acid to obtain cis-poly[(p-phenylenevinylene)-alt-(2,5-dioctyloxy-1,4-phenylenevinylene)] in a single form.

The classical result of Landau on the existence of kings in finite tournaments (=finite directed complete graphs) is extended to continuous tournaments for which the set X of players is a compact Hausdorff space. The following partial converse is proved as well. Let X be a Tychonoff space which is either zero-dimensional or locally connected or pseudocompact or linearly ordered. If X admits at least one continuous tournament and each continuous tournament on X has a king, then X must be compact. We show that a complete reversal of our theorem is impossible, by giving an example of a dense connected subspace Y of the unit square admitting precisely two continuous tournaments both of which have a king, yet Y is not even analytic (much less compact).Comment: The proof of item (iii) of Theorem 3.5 was rectified. Minor inconsistencies and typos were corrected. One reference was adde

Reaction of (Z)-styryl bromide (1) with PhB(OH) 2 in toluene at 80 °C for 1 h in the presence of Pd(PPh 3 ) 4 (1.5 mol %) and an aqueous solution of K 2 CO 3 (3 equiv) affords (Z)-stilbene as the crosscoupling product in 99% yield. On the other hand, the same reaction of the (E)-isomer of 1 forms considerable amounts of homocoupling products (1,4-diphenylbutadiene (2, 22%) and biphenyl (27%)) in addition to the cross-coupling product ((E)-stilbene, 73%). The formation of 2 was examined by kinetic experiments using trans-Pd(CHdCHPh)Br(PMePh 2 ) 2 (3) as a model of the presumed intermediate. Complex 3 reacts with 1 at 50 °C for 5 h, giving 2 (91%) and trans-PdBr 2 (PMePh 2 ) 2 (4, 92%), together with a small amount of Pd(η 2 -PhCHdCHPMePh 2 )Br(PMePh 2 ) (5, 8%). The reaction rate shows firstorder dependence on the concentration of 3 and 5, respectively, but is independent of the concentration of 1. A novel homocoupling process induced by P-C reductive elimination from 3 giving 5 is proposed.