Yasushi Kai

Single-Crystal-to-Single-Crystal Enantioselective [2+2] Photodimerization of Coumarin, Thiocoumarin and Cyclohex-2-enone in the Inclusion Complexes with Chiral Host Compounds

Abstract Single-crystal-to-single-crystal enantioselective [2+2] photodimerization reactions of coumarin (1a), thiocoumarin (1b) and cyclohex-2-enone (2) were found to proceed efficiently in inclusion complexes with (R,R)-(−)-trans-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxacyclopentane (3a), (R,R)-(−)-trans-2,3-bis(hydroxydiphenylmethyl)-1,4-dioxaspiro[4.4]nonane (3b), and (−)-1,4-bis[3-(o-chlorophenyl)-3-hydroxy-3-phenylprop-1-ynyl]benzene (4), respectively. Through these reactions, (−)-anti-head-to-head dimer 6a, (+)-anti-head-to-head dimer 6b and (−)-syn-trans dimer 10 were obtained in 100, 100 and 48% ee, respectively.

Catalytic activity of allyl-, azaallyl- and diaza-pentadienyllanthanide complexes for polymerization of methyl methacrylate ☆

Abstract A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compounds were synthesized and their polymerization catalysis toward methyl methacrylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl] 2 (THF) 2 1 and Sm(1,3-diphenylpropenyl) 2 (THF) 2 2 were synthesized by the reaction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphenylpropenide with SmI 2 . The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl 3 followed by the reaction with LiCH(SiMe 3 ) 2 to give (2-pyridylbenzyl) 2 SmCH(SiMe 3 ) 2 3 . 1,5-Diazapentadienyllanthanide was prepared by the reaction of K[(C 5 H 4 N) 2 CPh] with YbBr 2 to give Yb[(C 5 H 4 N) 2 CPh] 2 (THF) 2 4 , which crystalizes monoclinic, space group C 2/ C (No. 15), with a =35.19(1), b =13.613(3), c =26.552(7) A, β =133.77(1)°, and Z =8. Preparations of divalent samarium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilane ligand ( 6 and 7 ) were carried out by the reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI 2 or YbBr 2 . By using the resulting compounds 1 , 2 , 3 , 4 , 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and found that compounds 6 and 7 are effective to give high molecular weight isotactic polymers.

FERROMAGNETIC BEHAVIOR OF A TETRAFLUOROTETRACYANOQUINODIMETHANIDE SALT AT ROOM TEMPERATURE

Abstract Recrystallization of N(CH 3 ) 4 + · TCNQF 4 −. in the presence of TCNQF 4 from acetonitrile/ether gave a crystal of { N(CH 3 ) 4 + · TCNQF 4 −. }· 1 2 ( TCNQF 4 ) , which very interestingly exhibited ferromagnetism at temperature. This organic ferromagnet has characteristics of very small saturation moment (1.03 × 10 −3 μ B /molecule) and coercive field (≈ 25 Oe). The origin of this ferromagnetism could be attributed to a unique crystal structure of the radical anion salt: the TCNQF 4 /TCNQF 4 −. and N(CH 3 ) 4 + ion layers are alternately stacked and in the TCNQF 4 /TCNQF 4 −. layer each pair of two TCNQF 4 −. molecules is arranged in a completely perpendicular manner to each of one TCNQF 4 molecule.

1:2 TCNQ/TCNQ−. mixed salts exhibiting ferromagnetic behavior at room temperature

Abstract Ferromagnetic behavior at room temperature was observed in the tetramethylammonium (NMe + 4 ) and cesium (Cs + ) salts of tetracyanoquinodimethane (TCNQ) and its radical anion (TCNQ −. ) in a molecular ratio of 1:2. The saturation magnetizations and coercive forces are 0.79 emu/mol and ≈300 Oe for ( NMe + 4 · TCNQ −. ) · 1 2 TCNQ , and 1.46 emu/mol and ≈100 Oe for ( Cs +. · TCNQ −. ) · 1 2 TCNQ , respectively. In contrast, the 1:1 TCNQ/TCNQ −. mixed tetraethylammonium (NEt 4 + salt, (NEt 4 + ·TCNQ − ·)·TCNQ, exhibited no ferromagnetic behavior at room temperature nor at lower temperatures.

High polymerization of methyl methacrylate with organonickel/MMAO systems

A series of nickel complexes, including Ni(acac)2, (C5H5)Ni(η3-allyl), and [NiMe4Li2(THF)2]2, that were activated with modified methylaluminoxane (MMAO) exhibited high catalytic activity for the polymerization of methyl methacrylate (MMA) but showed no catalytic activity for the polymerization of ethylene and 1-olefins. The resulting polymers exhibited rather broad molecular weight distributions and low syndiotacticities. In contrast to these initiators, the metallocene complexes (C5H5)2Ni, (C5Me5)2Ni, (Ind)2Ni, and (Me3SiC5H4)2Ni provided narrower molecular weight distributions at 60 °C when these initiator were activated with MMAO. Half-metallocene complexes such as (C5H5)NiCl(PPh3), (C5Me5)NiCl(PPh3), and (Ind)NiCl(PPh3) produced poly(methyl methacrylate) (PMMA) with much narrower molecular weight distributions when the polymerization was carried out at 0 °C. Ni[1,3-(CF3)2-acac]2 generated PMMA with high syndiotacticity. The NiR(acac)(PPh3) complexes (R = Me or Et) revealed high selectivity in the polymerization of isoprene that produced 1,2-/3,4-polymer at 0 °C exclusively, whereas the polymerization at 60 °C resulted in the formation of cis-1,4-rich polymers. The polymerization of ethylene with Ni(1,3-tBu2-acac)2 and Ni[1,3-(CF3)2-acac]2 generated oligo-ethylene with moderate catalytic activity, whereas the reaction of ethylene with Ni(acac)2/MMAO produced high molecular weight polyethylene.

Synthesis and structure of a new type of C2-symmetric chiral crown ether

Abstract A new type of chiral crown ether, ( R,R )-2,12-bis(hydroxymethyl)-2,12-dimethyl-18-crown-6 possessing plural reactive functional groups, was isolated from a racemic mixture by lipase-catalyzed acetylation. The absolute configuration of the crown diol was determined based on the X-ray analysis of the complex of the derivative having plural oxyquinoline moieties with KI.

Diverse Mode of Crystal Structures in the Host-Guest Complexes of Diols

Abstract Crystal structures have been determined by X-ray diffraction method for the host-guest complexes with cis-l,4-diphenylcyclohexane-1,4-diol as the host molecule. The guest molecules are methanol, cis-2-betene-1,4-diol, trans-2-betene-1,4-diol, and trans-cyclohexane-1,4-diol in complexes 1 to 4, respectively. The host-guest interaction in these crystals are based on the hydrogen bond network between the hydroxyl groups of each component molecule. In these crystal structures, hydroxyl group behaves multifunctionally to form the diverse mode of host-guest interactions in these complexes.

Ferromagnetic Behavior of 1:2 TCNQ/TCNQ− Mixed Salts at Room Temperature

Abstract Ferromagnetic behavior at room temperature was observed in the tetramethylammonium (NMe4+) and cesium (Cs+) salts of tetracyanoquinodimethane (TCNQ) and its radical anion (TCNQ−) in a molecular ratio of 1:2. The saturation magnetizations and coercive forces are 0.79 emu/mol and ca. 300 Oe for (NMe4+·T·CNQ−)·l/2TCNQ, and 1.46 emu/mol and ca. 100 Oe for (Cs+·TCNQ−)·1/2TCNQ, respectively. In contrast, the 1:1 TCNQ/ TCNQ− mixed tetraethyammonium(NEt4+) salt, (NEt4+·TCNQ−)·TCNQ, exhibited no ferromagnetic behavior at room temperature and also at lower temperatures.

Crystal Structures and Magnetic Properties of Tetrafluorotetracyanoquinodimethanide Salts

Abstract The X-ray structure analyses of tetramethylammonium and tetraethylammonium salts of tetrafluorotetracyanoquinodimethanide (TCNQF4-*) (NMe4 +*TCNQF4* and NEt4 +*TCNQF4-*) were performed. In these crystals the TCNQF4-* molecules form dimers, which are stacked in a plane-to-plane manner to columns. Recrystallization of NMe4+*TCNQF4*-* in the presence of TCNQF4 (or TCNQ) gave a single crystal of (NMe4+*TCNQF4*)*½TCNQF4 (or TCNQ). The crystal is composed of alternating TCNQF4 (or TCNQ)/ TCNQF4-* and NMe4 + ion layers, and the TCNQF4 (or TCNQ)/ TCNQF4-* layer adopts a unique packing structure, in which each pair of two TCNQF4-* molecules is arranged in a completely perpendicular manner to each of one TCNQF4 (or TCNQ) molecule. The similar TCNQF4 (or TCNQ)/TCNQF4-* mixed salt was not obtained in use of NEt4+*TCNQF4-* at all.