Chiral Phosphine Oxide–Sc(OTf)3 Complex Catalyzed Enantioselective Bromoaminocyclization of 2-Benzofuranylmethyl N-Tosylcarbamates. Approach to a Novel Class of Optically Active Spiro Compounds

2015 ◽  
Vol 17 (23) ◽  
pp. 5752-5755 ◽  
Author(s):  
Zequan Li ◽  
Yian Shi
Keyword(s):  
Phosphine Oxide ◽  
Spiro Compounds ◽  
Optically Active

scholarly journals New routes to chiral phosphines

1985 ◽  
Author(s):  
Άγγελος Βουγιούκας
Keyword(s):  
Dicarboxylic Acid ◽  
Phosphine Oxide ◽  
Experimental Error ◽  
Phosphonium Salt ◽  
Optically Active ◽  
Side Chain ◽  
Phosphonium Salts ◽  
Unstable Compound ◽  
Chiral Phosphines ◽  
Optically Pure

The reaction of diphenyl(2-trimethylsilylethyl)phosphine with methyl trifluoromethanesulphonate gave a phosphonium salt from which the side-chain was cleaved with F ® , yielding diphenylmethylph osphine. A slower reaction with the triphenylsilyl-analogue gave the corresponding phosphine oxide. When the cleavage of a diphosphonium salt was attempted the product was a mixture of 1,3-bis-(diphenylphosphino)propane and diphenyl(2-trimethylsilylethyl)phosphine in 1:2 ratio showing the cleavage to be unselective. ß-Silylphosphonium salts derived from 2,2-dimethyl-H-methylene- 1 , 3-dioxolane reacted with F® to provide completely selective cleavage of the dioxolanyl side-chain, and a related bis-phosphonium salt gave only diphenyl(2-trimethylsilylethyl)phosphine under similar conditions. Greater selectivity towards fragmentation of the silylated side-chain was achieved with triethoxysilylethyl derivatives and 1, 3-bis-(diphenylphosphino)propane as well as 1,4-bis-(diphenylphosphino)butane were prepared in this way, in 86% and 9^% yield respectively. It was found that the dioxolanylmethyl side-chain was more readily cleaved from phosphonium salts than was 2-(triethoxylsily1)ethyl, however. In similar manner, reaction of 2-(trimethylsilyloxyethy1)- methyldiphenylphosphonium trifluoromethanesulphonate with Fö gave methyldiphenylphosphine oxide. The same reaction occurred when the corresponding hydroxyethylphosphine was treated with KH. This method was shown to be applicable to the synthesis of biphosphine oxides. Nevertheless, application to dioxolanylmethyl phosphonium salts again led to px^ef erential loss of that side-chain; this caused a change to utilisation of the trans-1,2-dimethylcyclobutyl backbone. The optically active o-anisylmethylphenylphosphine oxidewas prepared in both enantTomeric forms by a literature route. Reaction of the R-isomer with (iPr)2NLi and then acetone led to a new phosphine oxide which was reduced with E t 3N/Cl3$iH and reacted with methyl trifluoromethanesulphonate to giveR - (2-hydroxy-2-methylpropyl)(o-methoxyphenyl)methylphenylphosphonium trifluoromethanesplphonate. This reacted with KH to give the parent phosphineOKas R-enantiomer, optically pure within experimental error. “ A new route for the resolution of trans-cyclobutane-1,2-dicarboxylic acid has been developed. This involved the preparation of the bis-ephedrinium amide and its separationinto diastereomers by silica chromatography. The enantiomers were converted into SS and RR t r a n s - 1 ,2-cyclobutanedimethanolof 100% and 88% optical purTTy respectively. Whilst it proved possible to prepare the racemic bis-trifluoromethanesulphonate, it was an unstable compound and the optically active analogues could not be isolated in several attempts.

Synthesis of optically active 2-amino-1′-benzyl-2′,5-dioxo-5H-spiro[indeno[1,2-b]pyran-4,3′-indoline]-3-carbonitriles catalyzed by a bifunctional squaramide derived from quinine

2021 ◽  
Vol 45 (5) ◽  
pp. 2609-2613
Author(s):  
Yuanyuan Wang ◽  
Zhonglin Wei ◽  
Jungang Cao ◽  
Dapeng Liang ◽  
Yingjie Lin ◽  
...  
Keyword(s):  
Spiro Compounds ◽  
Optically Active ◽  
Asymmetric Reaction

The first organocatalytic asymmetric reaction of propylene malononitrile with oxoindole and 1,3-indandione for the synthesis of chiral indeno-spiro compounds has been developed.

Helical Twisting Power of Optically Active Spiro Compounds with a 3,3′-(4H,4′H)-Spirobi(2H-naphtho[1,2-b]pyran) Skeleton

2008 ◽  
Vol 37 (11) ◽  
pp. 1124-1125 ◽  
Author(s):  
Kenta Tojo ◽  
Tatsuya Arisawa ◽  
Yoshio Aoki ◽  
Daiyo Terunuma
Keyword(s):  
Spiro Compounds ◽  
Optically Active ◽  
Helical Twisting Power

Optically Active and C3-Symmetric Tris(pyrazolyl)hydroborate and Tris(pyrazolyl)phosphine Oxide Ligands: Synthesis and Structural Characterization

1994 ◽  
Vol 13 (7) ◽  
pp. 2855-2866 ◽  
Author(s):  
Daniel D. LeCloux ◽  
Christopher J. Tokar ◽  
Masahisa Osawa ◽  
Robert P. Houser ◽  
Michael C. Keyes ◽  
...  
Keyword(s):  
Phosphine Oxide ◽  
Structural Characterization ◽  
Optically Active

Optical analysis of ink and other contaminants in process waters

TAPPI Journal ◽  
2012 ◽  
Vol 11 (8) ◽  
pp. 51-58
Author(s):  
ANTTI HAAPALA ◽  
MIKA KÖRKKÖ ◽  
ELISA KOIVURANTA ◽  
JOUKO NIINIMÄKI
Keyword(s):  
Optically Active ◽  
Process Water ◽  
Paper Machine ◽  
Optical Analysis ◽  
Direct Process ◽  
Active Components ◽  
Water Contaminants ◽  
Dependent Measurement ◽  
Measurement Methodology

Analysis methods developed specifically to determine the presence of ink and other optically active components in paper machine white waters or other process effluents are not available. It is generally more interest¬ing to quantify the effect of circulation water contaminants on end products. This study compares optical techniques to quantify the dirt in process water by two methods for test media preparation and measurement: direct process water filtration on a membrane foil and low-grammage sheet formation. The results show that ink content values obtained from various analyses cannot be directly compared because of fundamental issues involving test media preparation and the varied methodologies used to formulate the results, which may be based on different sets of assumptions. The use of brightness, luminosity, and reflectance and the role of scattering measurements as a part of ink content analysis are discussed, along with fine materials retention and measurement media selection. The study concludes with practical tips for case-dependent measurement methodology selection.

Microscopic Structure of Er-Related Optically Active Centers in Si

2003 ◽  
Vol 770 ◽  
Author(s):  
H. Przybylinska ◽  
N. Q. Vinh ◽  
B.A. Andreev ◽  
Z. F. Krasil'nik ◽  
T. Gregorkiewicz
Keyword(s):  
Ground State ◽  
Photoluminescence Spectrum ◽  
Zeeman Effect ◽  
Optically Active ◽  
Single Type ◽  
Active Centers ◽  
Mbe Growth ◽  
Spectral Components ◽  
Er Doped ◽  
Successful Observation

AbstractA successful observation and analysis of the Zeeman effect on the near 1.54 μm photoluminescence spectrum in Er-doped crystalline MBE-grown silicon are reported. A clearly resolved splitting of 5 major spectral components was observed in magnetic fields up to 5.5 T. Based on the analysis of the data the symmetry of the dominant optically active center was conclusively established as orthorhombic I (C2v), with g‼≈18.4 and g⊥≈0 in the ground state. The fact that g⊥≈0 explains why EPR detection of Er-related optically active centers in silicon may be difficult. Preferential generation of a single type of an optically active Er-related center in MBE growth confirmed in this study is essential for photonic applications of Si:Er.

Sign in / Sign up

Export Citation Format

Share Document