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Thiophene Analogue of Isotanshinone‐II Nucleus: A Novel Approach towards the Synthesis of Phenanthro[4,3‐ b ]‐thiophene‐4,5‐dione and Phenanthro[3,4‐ b ]thiophene‐4,5‐dione Derivatives
Author(s) -
Sarkar Aparna,
Das Rumpa,
Kar Gandhi K.
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201802652
Subject(s) - thiophene , chemistry , naphthalene , acylation , moiety , intramolecular force , acetic acid , organic chemistry , medicinal chemistry , stereochemistry , catalysis
Abstract The phenanthraquinone moiety condensed with heteroarene moieties posses various therapeutic activities. In this article, synthesis of some novel thienophenanthraquinones ( eg . Phenanthro[4,3‐ b ]thiophene‐4,5‐dione / phenanthro[3,4‐ b ]‐thiophene‐4,5‐dione derivatives) is reported using a novel pathway developed by us. 3,4‐Dihydro‐1‐(2‐thienyl)naphthalene‐2‐carbaldehyde derivatives 3 a‐c were aromatized with DDQ to respective 1‐(2‐thienyl)naphthalene‐2‐carbaldehyde derivatives 4 a‐c . Conversion of the CHO functionality to CH 2 CO 2 H functionality was achieved in 4 steps to afford 2‐[1‐(2‐thienyl)naphthalene‐2‐yl]acetic acid derivatives 7 a‐c . Intramolecular Friedal‐Crafts acylation of these acids followed by Fremy's salt oxidation of the resulting phenanthro[4,3‐ b ]thiophene‐4‐ol derivatives 8 a‐c furnished the title compounds 9 a‐c in overall 7 steps. Following a similar route another novel thienophenanthraquinone [10‐methoxyphenanthro[3,4‐ b ]thiophene‐4,5‐dione 18 ] has also been synthesized. This synthetic route is very simple with fewer steps and is of good to excellent yields in most of the steps involved.