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Electroreductive Intermolecular Coupling of Chromones with Benzophenones: Synthesis of 2‐Diarylmethylchromones and Tetrasubstituted Furans
Author(s) -
Kise Naoki,
Nagamine Hiroaki,
Sakurai Toshihiko
Publication year - 2019
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201900519
Subject(s) - chemistry , adduct , ring (chemistry) , medicinal chemistry , dehydrogenation , trimethylsilyl , organic chemistry , catalysis
The electroreductive coupling of chromones with benzophenones in the presence of TMSCl gave adducts reacted at the 2‐position of chromones as trimethylsilyl ethers. From 3‐methyl‐ and 3‐phenylchromones, 2,3‐ cis ‐adducts were formed predominantly. The cis ‐adducts were isomerized to trans ‐ones by treatment with DBU. The detrimethylsilylation of the adducts with 1 M HCl aq/dioxane produced the corresponding alcohols. The dehydrosiloxylation of the adducts or dehydration of the desilylated alcohols brought about 2‐diarylmethylchromones. The detrimethylsilylation of the adducts with TBAF and subsequent treatment with NaH afforded ring‐opening products. The dehydration of the ring‐opening products obtained from 3‐methyl‐ and 3‐phenylchromons brought about tetrasubstituted furans or dihydrobenzofuran‐3‐ones. The dehydrogenation of the adducts with DDQ and subsequent desilylation with 1 M HCl aq/dioxane gave 2‐(diarylhydroxymethyl)chromones.