Showing papers by "Chizuko Kabuto published in 2000"
TL;DR: In this paper, a practical method for the synthesis of p-tert-butylthiacalix[4]arene (TC4A), in which the methylene bridges of C4A are replaced by epithio groups, is presented by heating a mixture of ptert butylphenol, elemental sulfur S8, and NaOH as a base catalyst in tetraethylene glycol dimethyl ether.
233 citations
TL;DR: Spectroscopic data indicate pronounced interaction between two remote silicon-silicon double bonds in the molecule, suggesting silicon- silicon bonds may be more accessible to synthesis than previously assumed.
Abstract: In contrast to carbon, silicon does not readily form double bonds, and compounds containing silicon-silicon double bonds can usually be stabilized only by protection with bulky substituents. We have isolated a silicon analog of spiropentadiene 1, a carbon double-ring compound that has not been isolated to date. In the crystal structure of tetrakis[tri(t-butyldimethylsilyl)silyl]spiropentasiladiene 2, a substantial deviation from the perpendicular arrangement of the two rings is observed, and the silicon-silicon double bonds are shown to be distorted. Spectroscopic data indicate pronounced interaction between two remote silicon-silicon double bonds in the molecule. Silicon-silicon bonds may be more accessible to synthesis than previously assumed.
76 citations
TL;DR: In this article, the selective de-tert-butylation of TCA derivatives with AlCl3 at 80°C has been investigated, and it was shown that TCA can detect metal cations directly by variation of fluorescence intensity upon addition of a metal cation.
58 citations
43 citations
TL;DR: In this article, stable disilenes having two different trialkylsilyl substituents [SiASiBSiSiSiASIB ((E)-2 and (Z)-2) and SiA2SiSiSiB2 (3), where SiA = t-BuMe2Si and SiB = i-Pr2MeSi] were prepared and characterized.
42 citations
TL;DR: The X-ray analysis revealed that TC6A adopted a distorted cone conformation stabilized by two sets of hydrogen bondings comprising three phenolic OH groups as mentioned in this paper, suggesting that the expanded central cavity and/or the crystal lattice of the former allowed a more comfortable accommodation of the guest molecules.
36 citations
TL;DR: In this article, a new stereoisomer of p-tert-butylsulfinylcalix[4]arene (2(ccc) with the four SO groups arranged in a cis-cis−cis configuration was given.
34 citations
TL;DR: The first chiral disulfinyldithiacalix[4]arenes were obtained by oxidation of two adjacent epithio groups of the tetramethyl ether of tetra( p-tert -butyl)tetrathiacaliz[4]-arene as mentioned in this paper.
33 citations
TL;DR: The CFTA method using α-cyano-α-fluoro-p-tolylacetic acid (CFTA) can be fairly reliable in assigning absolute configurations of chiral secondary alcohols based on both 1H and 19F NMR spectroscopy.
21 citations
TL;DR: The electron-deficient helicenes form charge-transfer (CT) complexes with pyrene in the solution as well as in the solid state as discussed by the authors, and the crystal of the CT complex obtained from either (P)- or (±)-tetranitrohelicene possesses columnar structure but with different helicity, diameter, and pitch.
Abstract: 1,12-Dimethylbenzo[c]phenanthrene-5,8-dinitrile is nitrated at symmetrical positions giving 2,11-dinitro-, 4,9-dinitro, and 2,4,9,11-tetranitrohelicenes depending on the reaction conditions. The electron-deficient helicenes form charge-transfer (CT) complexes with pyrene in the solution as well as in the solid state. Crystal of the CT complex obtained from either (P)- or (±)-tetranitrohelicene possesses columnar structure but with different helicity, diameter, and pitch.
16 citations
TL;DR: In this paper, a practical method for the synthesis of p-tert-butylthiacalix[4]arene (TC4A), in which the methylene bridges of C4A are replaced by epithio groups, is presented by heating a mixture of ptert butylphenol, elemental sulfur S8, and NaOH as a base catalyst in tetraethylene glycol dimethyl ether.
Abstract: A practical method for the synthesis of p-tert-butylthiacalix[4]arene (TC4A), in which the methylene bridges of p-tert-butylcalix[4]arene (C4A) are replaced by epithio groups, is presented by heating a mixture of p-tert-butylphenol, elemental sulfur S8, and NaOH as a base catalyst in tetraethylene glycol dimethyl ether. The inclusion behavior of TC4A for a wide range of solvent molecules is examined by recrystallization, showing preference for the guests depending upon the size and/or the substituent of the guests. The X-ray structure of a 1:2 host–guest complex of TC4A with 1,2-dichloroethane reveals that one guest molecule is included in the cavity of TC4A, while the other is included in the crystal lattice to form a clathrate-type complex. It is shown that the inclusion in the cavity is attained by a cooperative deformation of both the host and the guest.
TL;DR: In this article, the authors used diimide prepared in situ from p-toluenesulfonyl hydrazide in diglyme for the synthesis of saturated 12-and 18-membered oligosilacycloalkanes.
Abstract: The hydrogenation of bistrimethylsilylactylene, bis(trimethylsilyl)-1,3-diynes, and related silylalkynes giving the corresponding saturated compounds were achieved by using diimide prepared in situ from p-toluenesulfonyl hydrazide in diglyme. The present method was applicable to the synthesis of saturated 12- and 18-membered oligosilacycloalkanes.
TL;DR: Tetrakis (trimethylsilyl)-p-benzoquinone (1) was obtained by oxidation of hexakis(trimethylsilyl)hydroquinone with pyridinium chlorochromate.
Abstract: Tetrakis(trimethylsilyl)-p-benzoquinone (1) was obtained by oxidation of hexakis(trimethylsilyl)hydroquinone with pyridinium chlorochromate. X-Ray crystallographic analysis of 1 showed the quinone ring was distorted into a chair form by steric hindrance. Photolysis resulted in a rearrangement of the quinone ring and produced a ketene derivative.
TL;DR: In this article, the synthesis of novel five-membered cyclic ditellurides, 4-aryl-1,2,4,ditelluranazolidines, was achieved by treating 3,7-diaryl-2H,6H-tetrahydro-1.5,3,7,7diteluradiazocines with oxidizing agents or by aerobic exposure.
Abstract: Synthesis of novel five-membered cyclic ditellurides, 4-aryl-1,2,4-ditellurazolidines was achieved by treating 3,7-diaryl-2H,6H-tetrahydro-1,5,3,7-ditelluradiazocines with oxidizing agents or by aerobic exposure. The oxidative ring contraction of the heterocycles was assumed to proceed through formation and subsequent fragmentation of bicyclic ditellura dications.
TL;DR: In this article, sterically-crowded bornane-2-selones possessing substituted bornane skeletons with chloramine-T afforded several products originated from intermediary selone Se -imides, and the direct observation of the intermediates was performed by NMR monitoring at low temperature.
TL;DR: The reaction of cis-Cp*W(CO)2(MeCN)Me with CNtBu gave a mixture of the acetonitrile substitution products cis- and trans-cp*w(CO),2(CNtBu)Me and the CO insertion products cis and trans cp*cpw(Cpw, CO), 2(CN tBu), 2.2(COMe) as mentioned in this paper.
Abstract: The reaction of cis-Cp*W(CO)2(MeCN)Me with CNtBu gave a mixture of the acetonitrile substitution products cis- and trans-Cp*W(CO)2(CNtBu)Me and the CO insertion products cis- and trans-Cp*W(CO)(CNtBu)2(COMe). The substitution was favored at room temperature, while the insertion was favored at low temperature.