A stable atropisomer of 2,2′,6,6′-tetramethoxy-3,3′-dicarboxybiphenyl and optical resolution of 2,2′,6-trimethoxy-3-carboxybiphenyl

✍ Scribed by Masayoshi Okigawa; Yasuko Kawahara; Yohko Fujita; Noriko Hasaka; Nobusuke Kawano

• Book ID: 104237472
• Publisher: Elsevier Science
• Year: 1979
• Tongue: French
• Weight: 197 KB
• Volume: 20
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)85877-9

✦ Synopsis

has been reported1 to be non-resolvable because four methoxy-groups were considered inadequate fey obtaining restricted rotation and this fact is generally accepted.

2 Wowever, the fact was considered to be inconsistent with the isolation of optically active biflavonyls belonging to the Cupressuflavons, 3 amentoflavone, 4

and agathisflavone 5,6 series. These observations compelled us to reinvestigate the resolution of k.

Racemic $-was prepared by the reported method' showing m.p. 239-240" fUnC0r.) flit. 1 231-2320) and its structure was confirmed by elemental analysis and Spectral data. The dimethyl ester of X_meltsd at X38-139* funcor.) (from ethyl acetate). A brucine salt of $_ was easily obtained and Showed m-p.