3141-24-0Relevant articles and documents
BITHIENOLs: Promising C2-Symmetric Biheteroaromatic Diols for Organic Transformation
Gabrieli, Sara,Cirilli, Roberto,Benincori, Tiziana,Pierini, Marco,Rizzo, Simona,Rossi, Sergio
, p. 861 - 870 (2017)
2,2′,5,5′-Tetraphenyl-3,3′-bithiophene-4,4′-diol, the first member of a new class of chiral C2-symmetric atropisomeric diols based on a biheteroaromatic scaffold, has been synthesized. Dynamic enantioselective HPLC experiments revealed a racemization barrier of 22.9 kcal/mol at 25 °C, which is high enough to permit the chromatographic collection of both enantiomers on a semi-preparative scale, but at the borders of application as a promoter in asymmetric catalysis. The ground and transition states involved in the enantiomerization process have been identified through DFT calculations, which suggest the intermediacy of a tautomeric species in which a thiophen-3-ol unit and a 2,3-dihydrothiophen-3-one ring are present. The proposed racemization mechanism is supported by the results of dynamic HPLC experiments. Calculations also suggested which substituent groups at the 2,2′-positions of the thiophene rings could lead to an increase in enantiomerization barriers sufficient to confer full configurational stability on the 3,3′-bithiophene framework.
Photochromism of a diarylethene with methoxymethyl groups at reactive carbons: Thermal irreversible reaction of the closed-ring isomer
Kitagawa, Daichi,Kobatake, Seiya
, p. 93 - 95 (2011)
A photochromic diarylethene having methoxymethyl groups at the reactive carbons was synthesized, and the thermal stability of the closed-ring isomer was examined. The closed-ring isomer of the diarylethene caused both the thermal cycloreversion and a thermally irreversible reaction at 120°C. The structure of the thermal product was determined by 1H NMR, MS, and X-ray crystallographic analysis.
Structure and magnetic properties of an unusual homoleptic iron(iii) thiocyanate dimer
Dinsdale,Lough,Lemaire
, p. 11077 - 11082 (2015/06/25)
We describe the structural and variable temperature magnetic susceptibility properties of an unusual homoleptic bimetallic iron(iii) thiocyanate tetraanion. This work represents the first structurally characterized bis(μ-1,3-thiocyanato) dimer of iron(iii). A weak antiferromagnetic exchange interaction is observed between the two iron(iii) ions, which is supported by broken symmetry density functional theory (DFT) calculations.
Enatioselective Chalcogeno-Baylis-Hillman reaction of arylaldehydes with MVK and acrylates catalyzed by chiral thiepin-TiCl4 complex
Yin, Yan,Sun, Guofeng,Zhang, Heng,Zhou, Hong,Wu, Fanhong
supporting information, p. 365 - 369 (2014/05/20)
In a rational chiral molecular design of chalcogenides, optically active thiepin with C2-symmetric chirality was synthesized from commercially available thiophene. Then enatioselective Chalcogeno-Baylis-Hillman reactions of arylaldehydes with methyl vinyl ketone (MVK) and acrylates were investigated in the presence of thiepin-Lewis acid complex. Finally, up to 64% ee was achieved in the presence of 0.2 equiv. of (S)-thiepin at 20°C. Enatioselective Chalcogeno-Baylis-Hillman reactions between benzaldehydes and acrylates were investigated in the presence of chiral thiepin-Lewis acid complex. Finally, up to 64% ee was achieved in the presence of 0.2 equiv. of (S)-thiepin at 20°C. Copyright
