2,3-Bis(diphenylphosphino)-1,3-butadien

2,3-Bis(diphenylphosphino)-1,3-butadiene A method for synthesis of the title compound is described, using the readily available 2,3-bis(diphenylphosphinoyl)-1,3-butadiene ( 1 ) as the starting material. For the protection of the diene system, 1 is first converted into the 1,4-dibromo- and 1,4-dichloro derivatives 2a and b , respectively, by addition of Br₂ or Cl₂, respectively. The structure of 2b has been determined by single-crystal X-ray diffraction. The molecule has a centrosymmetrical (E)-configuration. Reduction of the phosphinoyl groups by HSiCl₃(to give the bis(diphenylphosphino)compound 3), followed by removal of the Cl-atoms using Zn powder, affords the bis(diphenylphosphino)butadiene 4 . Compounds 3 and 4 give quaternary phosphonium salts 5 and 6 , respectively, on addition of CH₃OSO₂F or CH₃I. The sulfur analogue of 1 is formed on treatment of 4 with elemental sulfur.     

Oxidation of Poly(2,3-dimethylbutadiene-1,3)

Abstract

Poly(2,3-dimethylbutadiene-1,3) containing cis-1,4, trans-1,4, and 1,2 structural units in various proportions undergoes rapid oxidation even at room temperature. The process of oxidation is accompanied by cyclization. The concentration of peroxides that form at room temperature is relatively very high, reaching the value of one peroxidic group per 16 monomeric units. The formation of six-membered rings involving the peroxidic bonds in poly(2,3-dimethylbutadiene) is accompanied by degradation.     

2,3-O-Isopropyliden-L-Sorbofuranose (MIPSF) und 2,3; 4,6-Di-O-Isopropyliden-L-Sorbofuranose (DIPSF)

Ohne Zusammenfassung     

Über den einfluss von chlor-substituenten auf die bildungstendenz und bindungsverhältnisse des tricarbonyl(buta-1,3-dien)eisen: Tricarbonyl(2,3-dichlorbuta-1,3-dien)eisen und tricarbonyl(2-chlorbuta-1,3-dien)eisen

Frequencies of carbonyl stretching vibrations and relative yields in syntheses of tricarbonyl(2,3-dichlorobuta-1,3-diene)iron and tricarbonyl(2-chlorobuta-1,3-diene)iron are discussed with respect to possible steric effects of chloro-substituents on the formation of tricarbonyl(hexachlorobuta-1,3-diene)iron.     

Gold‐Catalyzed Stereocontrolled Synthesis of 2,3‐Bis(acetoxy)‐1,3‐dienes

Change the ligand, change the stereochemistry : 2,3‐Bis(acetoxy)‐1,3‐dienes are obtained in a stereocontrolled manner by a novel tandem 1,2‐/1,2‐bis(acetoxy) rearrangement (see scheme, R¹ and R² are δ⁺ stabilizing). Upon stabilization of the reaction intermediates, the ligand attached to gold controls the stereochemistry of the alkene in the second acetate migration, that is, N‐heterocyclic carbenes (NHC) favor cis alkenes, whereas phosphine ligands selectively afford trans olefins.

     

Thermal oligomerization of methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)buta-2,3-dienoate

Dimeric compounds formed as a result of thermal oligomerization of methyl 4-(1,3-dioxo-2,3- dihydro-1H-isoindol-2-yl)buta-2,3-dienoate were identified.     

2,3-二苯基-1,4-二氮杂-1,3-环庚二烯和2,3-取代喹啉的铜(II)配合物研究

were prepared These compounds have linear chain structures with bridging L which were deduced from ESR and variable-temp. magnetic susceptibility data. The ESR spectra of complexes formed between CuX2 and substituted quinoxalines (2-Me, 2,3-di-Me and 2,3-diphenyl) are described.     

Synthesis and polymerization of 1,3-bis-(2,3-epoxypropylphenyl)tetramethyldisiloxanes and related compounds

1,3-Bis[p-(2,3-epoxypropyl)phenyl]tetramethyldisiloxane and its meta isomer were synthesized and subsequently cured with m-phenylenediamine. Dielectric properties of the cured resin derived from the para isomer were measured between 25 and 100°C. The ambient temperature dielectric constant of the resin at 1 kc./sec. was 3.4, its dissipation factor was 0.01, and its volume resistivity was 10¹⁴ ohm-cm. at 500 v. d.c. Several allylphenylsiloxanes were also prepared by the cohydrolysis of allylphenyldimethylethoxysilane with dimethyldiethoxysilane, bis(dimethylethoxysilyl)benzene, and methyltriethoxysilane. Preliminary epoxidation studies on these latter materials were also carried out.