62019-26-5Relevant academic research and scientific papers
Formal [4 + 1] cycloaddition of o-quinone methides: Facile synthesis of dihydrobenzofurans
Lei, Xiantao,Jiang, Chun-Huan,Wen, Xiaoan,Xu, Qing-Long,Sun, Hongbin
, p. 14953 - 14957 (2015/03/05)
An efficient and straightforward method for the rapid synthesis of 2-substituted dihydrobenzofurans has been developed via reaction of sulfur ylides with o-quinone methides (o-QMs), which were generated under mild conditions. The products could be obtaine
Quaternary ammonium (Hypo)iodite catalysis for enantioselective oxidative cycloetherification
Uyanik, Muhammet,Okamoto, Hiroaki,Yasui, Takeshi,Ishihara, Kazuaki
scheme or table, p. 1376 - 1379 (2011/07/31)
It is desirable to minimize the use of rare or toxic metals for oxidative reactions in the synthesis of pharmaceutical products. Hypervalent iodine compounds are environmentally benign alternatives, but their catalytic use, particularly for asymmetric transformations, has been quite limited. We report here an enantioselective oxidative cyeloetherification of ketophenols to 2-acyl-2,3-dihydrobenzofuran derivatives, catalyzed by in situ-generated chiral quaternary ammonium (hypo)iodite salts, with hydrogen peroxide as an environmentally benign oxidant. The optically active 2-acyl 2,3- dihydrobenzofuran skeleton is a key structure in several biologically active compounds.
Synthesis of Biflavonoids in which the Flavan Units are linked through Oxygen from C-2 to C-3 or C-4
Brown, Ben R.,Stuart, Ian A.,Tyrrell, A. William R.
, p. 2563 - 2572 (2007/10/02)
Flav-2-enes have been utilised via 2,3-cis-2-acetoxy-3-bromoflavans for the synthesis of C-2-O-C-3- and C-2-O-C-4-linked biflavonoids.For example, 2,3-cis-2-acetoxy-3-bromoflavans react with (+/-)-tetra-O-methylcatechin (18) to give
Reactions of Flav-2-enes and Flav-2-en-4-ones (Flavones)
Bird, T. Geoffrey C.,Brown, Ben R.,Stuart, Ian A.,Tyrrell, William R.
, p. 1831 - 1846 (2007/10/02)
Flav-2-enes, flavones, and 3-alkyl ethers of flavonols add alcohols and carboxylic acids in the presence of N-bromosuccinimide to give 2-alkoxy- and 2-acyloxy-3-bromoflavans which provide routes to cis-3-bromoflavans by reduction and to 3,4-diols by elimination and reaction with osmium tetraoxide.The 2-acyloxyflavans react with alcohols yielding 2-alkoxyflavans.Flavonols react with N-bromosuccinimide and alcohols to give bromine-free hemiacetals, the known 2,3-dialkoxy-3-hydroxyflavanones.
