Dihydroretinoic acids and their derivatives. Synthesis and biological activity
摘要:
The syntheses of the ring and four side-chain dihydroretinoic acids and/or their esters, 3-7, are described. The syntheses of several other retinoids containing a substituted aromatic ring are also included. The biological activity of the compounds was evaluated in vivo in a chemically induced mouse skin papilloma test and in vitro in two vitamin A deficient assays. The activity observed for 1a, 1c, and 2a in the former test was partially retained in the dihydro derivatives 4b, 4c, and 6b. Similar results were found in the in vitro assays.
Benzyne 1,2,4-Trisubstitution and Dearomative 1,2,4-Trifunctionalization
作者:Jiarong Shi、Lianggui Li、Chunhui Shan、Zhonghong Chen、Liang Dai、Min Tan、Yu Lan、Yang Li
DOI:10.1021/jacs.1c04389
日期:2021.7.21
4-trifunctionalization of benzyne have been accomplished from sulfoxides bearing a penta-2,4-dien-1-yl moiety. These cascade transformations proceed through a benzyne insertion into the S═O bond and an uncommon regiospecific anionic [4,5]-sigmatropic rearrangement, furnishing a C–O, C–S, and C–C bond on the C1-, C2-, and C4-position of a benzene ring, respectively. This study showcases new cascade benzyne reaction
Ammonium Salt-Catalyzed Highly Practical <i>Ortho</i>-Selective Monohalogenation and Phenylselenation of Phenols: Scope and Applications
作者:Xiaodong Xiong、Ying-Yeung Yeung
DOI:10.1021/acscatal.8b00327
日期:2018.5.4
An ortho-selective ammonium chloride salt-catalyzed direct C–H monohalogenation of phenols and 1,1′-bi-2-naphthol (BINOL) with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) as the chlorinating agent has been developed. The catalyst loading was low (down to 0.01 mol %) and the reaction conditions were very mild. A wide range of substrates including BINOLs were compatible with this catalytic protocol. Chlorinated
Regioselective synthesis of important chlorophenols in the presence of methylthioalkanes with remote SMe, OMe or OH substituents
作者:Keith Smith、Ali J. Al-Zuhairi、Mark. C. Elliott、Gamal A. El-Hiti
DOI:10.1080/17415993.2018.1493111
日期:2018.11.2
ABSTRACT Various methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes have been used as regioselectivity modifiers in the chlorination reactions of various phenols at room temperature. The process involves the use of a slight excess of sulfuryl chloride in the presence of aluminum or ferric chloride as an activator. Methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes
Regioselective chlorination of phenols in the presence of tetrahydrothiopyran derivatives
作者:Keith Smith、Des Williams、Gamal A. El-Hiti
DOI:10.1080/17415993.2019.1620230
日期:2019.9.3
have been used as moderators in chlorination reactions of various phenols with sulfuryl chloride in the presence of aluminum or ferric chloride. On chlorination of phenol, ortho-cresol and meta-cresol the para/ortho chlorination ratios and yields of the para-chloro isomers are higher than when no cyclic sulfide is used for all of the cyclic sulfides, but chlorination of meta-xylenol is less consistent
<i>para</i>-Selective chlorination of cresols and <i>m</i>-xylenol using sulfuryl chloride in the presence of poly(alkylene sulfide)s
作者:Keith Smith、Amany S. Hegazy、Gamal A. El-Hiti
DOI:10.1080/17415993.2020.1740226
日期:2020.7.3
o-cresol, m-cresol, and m-xylenol using sulfuryl chloride in the presence of a range of poly(alkylene sulfide)s and a Lewis acid (aluminum or ferric chloride) has been studied. The sulfur containing catalysts used led to the production of para-chlorophenols in high yields and higher para/ortho ratios than for reactions in the absence of such poly(alkylene sulfide)s. The effectiveness of the polymers