Copper-catalyzed asymmetric propargylic substitution of anthrones and propargylic esters

Anthrones are key structural motifs in many natural products, bioactive compounds and pharmaceutical chemicals. Earth-abundant-metal-catalyzed asymmetric functionalization of anthrones has not proved to be viable. Herein, we disclosed a highly enantioselective propargylic substitution of anthrones with propargylic esters using copper salts with chiral N, N, P-ligand. This strategy is amenable to a broad range of substrates, uses readily available starting materials, provides excellent yields with remarkable enantioselectivity under mild conditions, and enables attractive products diversification routes.

Enantioselective synthesis of 10-allylanthrones via iridium-catalyzed allylic substitution reaction

A highly enantioselective allylic substitution reaction of anthrones with aromatic or aliphatic allyl carbonates was realized by using iridium catalyst prepared from [Ir（COD）CI]2 and BHPphos. Substituted 10-allylanthrones were obtained in excellent yields and with excellent enantioselectivity and regioselectivity （up to 98% yield, 99700 ee） under mild conditions.

Identification of the multiple bioactive derivatives and their endogenous molecular targets that may mediate the laxative effect of rhubarb in rats

Objective:To determine the mechanism of the laxative effect of rhubarb(Rheum tanguticum Maxim.ex Balf.)in rats using a combined bioinformatic and in vivo approach.Methods:Substances derived from rhubarb that are present in the colorectum were identified using high-performance liquid chromatography,coupled with linear ion-trap quadrupole Orbitrap highresolution mass spectrometry.The targets with a potential laxative effect were identified from databases and the literature,then used with rhubarb-derived substances in molecular docking modeling.The expression of candidate endogenous target molecules that bound specific components of rhubarb was then measured in constipated rats that had or had not been administered rhubarb by western blotting.Finally,potentially bioactive compounds were traced back to their prototype components.Results:We identified 17 anthraquinones and 21 anthrones derived from rhubarb in the colorectum of rats.G-scoring identified three potential mediators of the laxative effect:c-kit,5-hydroxytryptamine receptor 4(5-HT4),and aquaporin-3(AQP3).In addition,10 rhubarb-derived components(aloeemodin,emodin,rhein,chrysophanol,physcion,sennoside A,sennoside C,physcionanthrone,aloeemodinanthrone,and rheinanthrone),which have strong binding affinities for more than one of the three potential targets,were selected as likely active compounds.Rhubarb extract increased the expression of c-kit and 5-HT4,and reduced the expression of AQP3 in the colon of constipated rats,which might mediate its laxative effect.We also found that a single prototype component may be metabolized into several active metabolites,and a single active ingredient can also be generated from various prototype compounds.Conclusion:The present study demonstrates that various anthraquinones and anthrones present in rhubarb may be metabolized to form bioactive compounds that have additive or synergistic effects to promote defecation via c-kit,5-HT4 and/or AQP3.

Electrocarboxylation of Anthrone to Anthracene-9-carboxylic Acid in the Presence of CO_2

Electrocarboxylation of anthrone in the presence of CO2 to anthrance-9-carboxylic acid directly was carried out. The electroreduction behavior of anthrone was examined by cyclic voltammetry in the absence and presence of CO2. Then the influences of the supporting electrolytes, temperature, electrode material and anthrone concentration on the carboxylation yield were investigated. Under the optimized conditions, anthrancene-9-carboxylic acid was obtained in a good yield（96.1%）.

Crystal Structure of 10-(2',5'-Dimethoxybenzylidene) Anthrone

The anthrone reacts with 2,5-dimethoxybenzaldehyde under base catalyst to afford the title compound (C23H18O3, Mr = 342.37). The crystal belongs to monoclinic, space group P21/c with a = 13.046(4), b = 8.937(2), c = 15.549(4) ? b = 106.52(3), V = 1738.1(8) 3, Z = 4, Dc = 1.308 g/cm3, m = 0.086 mm-1 and F(000) = 720. The final R = 0.0331 and wR = 0.0850. The results show that the two phenyl rings of the anthrone fragment are not coplanar, but with a dihedral angle of 157.92. The middle ring of the anthrone moiety appears asymmetric boat conformation, while the 2,5-dimethoxyphenyl ring is restricted rotation. Therefore they exist in two optically active forms which are symmetrical glidingly.

A New 10-Hydroxyl Anthrone Glycoside from Cassia siamea Lam

A new 10-hydroxyl anthrone glycoside, 1, 8, 10 - trihydroxyl-1ObDglucopyrano- syl-3-methyl-10- C (S) b D- glucopyranosyl-anthrone-9 1 was isolated from the stem of Cassia siamea Lam. The structure was elucidated by spectral evidences, especially by 2 D techniques.