138746-87-9Relevant articles and documents
Highly enantioselective homogeneous catalysis of chiral rare earth phosphates in the hetero-Diels-Alder reaction
Furuno, Hiroshi,Kambara, Takeshi,Tanaka, Yumiko,Hanamoto, Takeshi,Kagawa, Takumi,Inanaga, Junji
, p. 6129 - 6132 (2003)
Two types of novel rare earth (RE) complexes were synthesized and used as a chiral Lewis acid catalyst for the hetero-Diels-Alder reaction of carbonyl compounds with the Danishefsky's diene under homogeneous conditions. The Y[(R)-H8-BNP]3
Molecular Clefts Derived from 9,9'-Spirobi for Enantioselective Complexation of Pyranosides and Dicarboxylic Acids
Cuntze, Jens,Owens, Linda,Alcazar, Victoria,Seiler, Paul,Diederich, Francois
, p. 367 - 390 (1995)
The molecular elefts (R)-and (S)-3, incorporating 9,9'-spirobi as a spacer and two N-(5,7-dimethyl-1,8-naphthyridin-2-yl)carboxamide (CONH(naphthy)) units as H-bonding sites were prepared via the bis(succinimid-N-yl esters) of (R)- and (S)-9,9'-spirobi-2,2'-dicarboxylic acid (5).Derivative 6, with one CONH(naphthy) unit and one succinimid-N-yl ester residue allowed easy access to spirobifluorene elefts with two different H-bonding sites, as exemplified by the synthesis of 4.Binding studies with (R)- and (S)-3 and optically active dicarboxylic acids in CDCl3 exhibited differences in free energy of the formed diastereoisomeric complexes (Δ(ΔG0)) between 0.5 and 1.6 kcal mol-1 (T 300 K).Similar enantioselectivities were observed with the spirobifluorene clefts (R)-and (S)-1, bearing two N-(6-methylpyridin-2-yl)carboxamide (CONH(py)) H-bonding sites.The thermodynamic quantities ΔH0 and ΔS0 for the recognition processes with (R)- and (S)-1 were determined by variable-temperature (1)H-NMR titrations and compared to those with (R)- and (S)-2, which have two CONH(py) moieties attached to the 6,6'-positions of a conformationally more flexible 1,1'-binaphthyl cleft.All association processes showed high enthalpic driving forces which are partially compensated by unfavorable changes in entropy.Pyranosides bind to the optically active clefts 1 and 3 in CDCl3 with -ΔG0 = 3.0-4.3 kcal mol-1.Diastereoisomeric selectivities up to 1.2 kcal mol-1 and enantioselectivities up to 0.4 kcal mol-1 were observed.Cleft 4 and N-(5,7-dimethyl-1,8-naphthyridin-2-)acetamide (25) complexed pyranosides 22-24 as effectively as 3 indicating that only one CONH(naphthy) site in 3 associates strongly with the sugar derivatives.Based on the X-ray crystal structure of 3, a computer model for the complex between (S)-3 and pyranosiide 22 was constructed.Molecular-dynamics (MD) simulations showed that differential geometrical constraints are at the origin of the high enantioselectivity in the complexation of dicarboxylic acid (S)-7 by (R)- and (S)-1 and (R)- and (S)-3.
The nature of 6,6′-bis(triphenylamine) substituted BINOL as chromophoric and fluorogenic hybrid chemosensor for selective fluoride detection
Chen, Chi-Hsiang,Leung, Man-Kit
experimental part, p. 3924 - 3935 (2011/06/24)
6,6′-Bis(triphenylamine)-1,1′-binaphthyl-2,2′-diol (1) is highly fluorescent in visible region. On treatment with a variety of anions, the UV-vis absorption as well as the fluorescent behavior of 1 in CH 2Cl2 is substantially changed
