Cholesteric medium inductive asymmetric polymerization: preparation of optically active polythiophene derivatives from achiral monomers in cholesteric liquid crystals

This Letter reports the synthesis and optical properties of polythiophenes prepared in cholesteric liquid crystal (CLC) medium. The polythiophenes prepared from achiral monomers in the CLC display consistent optical activity. In the first step of this research, we prepared CLCs for a reaction solvent. Next, Stille-type polycondensation reaction in the CLC was carried out. The resultant polymers show intense circular dichroism (CD). The CD results suggest that the polymers form a chiral structure.     

Exo- and endo-palladacycles derived from (4R)-phenyl-2-oxazolines

Two novel oxazoline-derived palladacycles bearing an endo- or exo-CN bond were prepared by direct ortho-palladation of (R)-2,4-diphenyl- or (R)-2-methyl-4-phenyl-2-oxazolines, respectively. The structures of the palladacycles' dimeric forms and corresponding mononuclear PPh₃-derivatives were confirmed by IR, ¹H, ¹³C and 2D NMR spectroscopy. An X-ray diffraction study of the μ-chloro-dimeric cyclopalladated derivative of (R)-2,4-diphenyl-2-oxazoline proved the endo structure of the palladacycle.     

α-(3,7-Dioxa-r-1-azabicyclo[3.3.0]oct-c-5-ylmethoxy)-diazines. Part 2: Functionalisation via directed ortho-metallation and cross-coupling reactions

The functionalisation of the title compounds via regioselective Directed ortho-Metallation (DoM) and cross-coupling reactions is studied. The compatibility of the 3,7-DiOxa-r-1-AzaBicyclo[3.3.0]Oct-c-5-ylmethoxy system (DOABO-CH₂O) to typical reaction conditions is established. Its role as Directed ortho-Metallation Group (DoMG) is examined, including competition with classical DoMGs, chlorine and methoxy. The chelating ability of some functionalised terms such as DOABO-CH₂O substituting chiral diarylmethanols and polyaza analogues of 2,6-terpyridine is discussed as intramolecular steric relationships determining configuration and aptitude to bind selectively transition metals, respectively.     

Enantiospecific access to 10-N-substituted camphors

A general and straightforward enantiospecific access to synthetically valuable 10-N-substituted camphors (amines and secondary amides) has been developed. The synthetic method uses camphor as the starting enantiopure material and takes place in five individual steps with a high overall yield. The process involves a stereocontrolled double-Wagner-Meerwein-rearrangement strategy to generate key-intermediate 10-(triflyloxy)camphor, a peculiar and highly-reactive primary triflate, which is able to alkylate soft N-nucleophiles, such as amines and nitriles, easily and without producing Grob-like fragmentation of the β-(triflyloxy)ketone-based norbornane system.     

Chiral self-assembly regulated photon upconversion based on triplet-triplet annihilation

Triplet-triplet annihilation based photon upconversion (TTA-UC) were constructed successfully by chiral self-assembly strategy.Enhanced TTA-UC could be obtained in the racemic assemblies compared with the homochiral assemblies.     

碳－碳不饱和键的硼氢化反应在有机合成中的应用新进展

综述了近年来碳－碳不饱和键的硼氢化反应在有机合成中的应用，包括醇、酮、酸、胺、卤代烃、腈化物和烯的合成。参考文献３５篇。     

“Pinwheel-like” phthalocyanines with four non-peripheral chiral menthol units: Synthesis,spectroscopy, and electrochemistry

Chiral side chains have been incorporated onto the non-periphery moiety of phthalocyanine ring, resulting in a pair of chiral phthalocyanines, (D)-and (L)-1,8,15, 22-tetrakis(2-isopropyl-5-methylcyclohexoxyl)phthalocyanine.     

Chirale Dimethylgalliumaminoalkoxide

Chiral Dimethylgallium Amino Alkoxides Me₃Ga reacts with (S)-1-methyl-2-pyrrolidinyl-methanol, (+);(–)-2-piperidyl-methanol, and (S)-α,α,-diphenyl-2-pyrrolidinyl-methanol in molar ratio 1 : 1 with formation of the corresponding dimethylgallium aminoalkoxides 1 – 3 . As a consequence of the Ga–N-interaction new centres of chirality containing asymmetric surrounded N-atoms are formed. Compounds 1 – 3 were characterized by their ¹H, ¹³C nmr and mass spectra. The crystal structures of 1 – 3 were determined by single crystal structure analysis. 1 and 2 are dimeric in solid state, 3 is forming monomeric molecules. 1 and 3 crystallize in the monoclinic space group P2₁ with Z = 2, a = 7.245(4), b = 11.887(3), c = 11.807(6) Å, β = 93.48(3)° for 1 and Z = 4, a = 11.0871(7); b = 6.539(4), c = 12.6919(8) Å, β = 107.04(1)° for 3 . 2 and 2 a crystallize in the monoclinic space groups C2/m and C2/c with Z = 2, a = 15.891(3), b = 9.526(2), c = 7.345(1) Å, β = 111.89(3)° for 2 and Z = 4, a = 19.374(4), b = 8.430(2), c = 19.961(4) Å, β = 100.09(3)° for 2 a .     

C3 Symmetry in Asymmetric Catalysis and Chiral Recognition

Rotational symmetry can be an important factor in the design of highly selective receptors for chiral recognition. This is well known for C₂-symmetric compounds, but the concept can be extended to chiral compounds of higher symmetry such as 1 .     

A Strong Positive Allosteric Effect in the Molecular Recognition of Dicarboxylic Acids by a Cerium(IV) Bis[tetrakis(4-pyridyl)porphyrinate] Double Decker

With increasing number of bound dicarboxylic acid molecules , the binding of further molecules by the title compound becomes more favorable (a 1:4 complex is depicted schematically on the right). The association constant for binding of the first guest molecule is small, since the increase in Gibbs free energy due to binding is outweighed by the energy loss asssociated with the suppression of rotation of the porphyrin rings. Once rotation has been suppressed, further guest molecules can be more effectively bound (positive allosteric effect).