121056-97-1Relevant articles and documents
Understanding the regioselectivity in the oxidative condensation of catechins using pyrogallol-type model compounds
Yanase, Emiko,Ochiai, Yuto,Hirose, Sayumi
, p. 12359 - 12366 (2020)
Catechins are found in many foods, including tea. These compounds are bioactive. Previous studies have shown that catechins form dimers on oxidation, and there seem to be distinct regioselective effects. However, the dimerization mechanism and regioselectivity are not well understood. Therefore, we investigated the oxidation of four pyrogallol-type model compounds of epigallocatechin (EGC) having various substituents with 1 equiv of copper chloride and 30% dioxane in water. Compounds having 2C-2C or 2C-4C bonds in the B-ring were obtained in different product ratios. Comparison of the oxidation rates of each compound revealed that the model compounds having an oxygen atom corresponding to the 1-position of the C-ring of EGC underwent slow oxidation. In addition, using density functional theory calculations, we found that the highest occupied molecular orbital energies of these compounds were higher than those of the others. Further, the 2C-2C-bonded oxidation product having an A-ring and an oxygen atom at the C-ring 1-position was confirmed to have the highest thermodynamic stability. From these results, it is suggested that the regioselective condensation reaction of the catechin B-ring is related to interactions between the A-rings, as indicated by earlier studies, and the presence of oxygen at the 1-position of the C-ring in EGC.
Preferential formation of columnar mesophases via peripheral modification of discotic π-systems with immiscible side chain pairs
Sakurai, Tsuneaki,Tsutsui, Yusuke,Kato, Kenichi,Takata, Masaki,Seki, Shu
supporting information, p. 1490 - 1496 (2016/02/23)
When sufficient volume of dodecyl chains are attached at one imide position of a perylenediimide (PDI) or naphthalenediimide (NDI) core and triethyleneglycol (TEG) chains on the other side, the resulting molecules PDIC12/TEGG0, PDIC12/TEGG1, and NDIC12/TEGG0 self-assemble into a rectangular columnar mesophase with p2mg symmetry, forming hydrophobic/hydrophilic nano-segregation of side chains. The driving force of PDIC12/TEGG0 to form preferentially the rectangular columnar mesophase is given by the immiscibility between the side chain pairs - exclusion of other phases such as cubic, crystalline and amorphous phases, where thermodynamically unstable contacts between hydrophobic and hydrophilic chains considerably take place. In contrast, this preference is less found in the analogous molecules decorated with either dodecyl or TEG chains at both termini. PDIC12/C12G0 and PDITEG/TEGG0 form a hexagonal columnar mesophase because of the optimized chain/core volume. However, if the side chain volume grows, PDITEG/TEGG1 does not form a mesophase but undergoes a soft crystalline-isotropic phase transition, while PDIC12/C12G1 was revealed to destabilize its columnar mesophase but forms a micellar cubic phase. NDIC12/C12G0 resulted in a strong crystallization, while NDITEG/TEGG0 formed amorphous liquid. The molecular design strategy using immiscible side chain pairs potentially enables a variety of π-systems to stack up to form a columnar phase rather than other ordered phases, regardless of the chain/core volume balance.
Synthesis of Unprotected (+/-)-Tunichrome An-1, a Tunicate Blood Pigment
Horenstein, Benjamin A.,Nakanishi, Koji
, p. 6242 - 6246 (2007/10/02)
The unstable, oxygen-sensitive tunicate blood pigment (+/-)-tunichrome An-1 (1a), which has been implicated in the 1E7-fold concentration of vanadium from the ocean is some tunicate species, has been synthesized in its underivatized form on a semipreparat
