Configuratio, Conformation and Rotatory Dispersion of Optically Active Biaryls

Abstract

OPTICALLY ACTIVE BIARYLS 1455 m.p. 139-141.5', infrared spectrum identical with that of startingmaterial, [ a ] * 6~ 0.0' ( G 1.1,i 2 , benzene). B.-Thermostated solutions ( 10jo) of (-)-I in redistilled o-xylene were examined polarimetrically (2-dm. tube) over a period of a t least one half-life. Readings were taken a t 435 m r and the results were plotted as log at ws. time. Excellent straight-line relationships resulted from the minimum of fifteen readings which were obtained for each run. The values of k obtained from the slopes of the curves are listed inTableI. Anal. Calcd. for ClsHls02: C, 81.17; H, 6.81. Found: C, 81.44; H, 6.94. The (+)-isomer ([a]*% -k 25' (C 0.99 chloroform)) Was obtained by decomposition of the salt ([aIp8D -68' (C 1.0, chf.)) which precipitated from (*)-I and W n i n e in acetone.The product was not further investigated.A.-A 1% solution of ( -1-

Lignans from Schisandra sphenathera Rehd. et Wils. and semisynthetic schisantherin A analogues: Absolute configuration, and their estrogenic and anti-proliferative activity

“…Such a correlation was first observed by Ikeya et al [14,24] and has been applied to establish the absolute configuration of several dibenzocyclooctadiene lignans and related compounds. It is based on the more general and well-known biaryl helicity rule, established by Mislow [25] in the early 1960s and subsequently interpreted on a theoretical ground [26,27]. Schisandrin A1 (1) contains however, in addition to the substituted dibenzocyclooctadiene, a second strong chromophore, the benzoate, which cannot be overlooked in the CD analysis.…”

The Metabolism of Gallic Acid and Hexahydroxydiphenic Acid in Higher Plants

“…The racemic forms were resolved via their quinidine and cinchonine salts. The half-life for racemisation of the methoxy acid (25) was determined as 14 3 / 4 hr in refluxing aqueous alkali and for the hydroxy acid (27) -produced by hydrogenolysis of (26) (72,76) MISLOW and DJERASSI (54), by applying the amide rule of the glyconic acids to the biphenyl system of the ( + )-hexahydroxydiphenoyl group in corilagin (28), (~-I-o-galloyl-3,6-hexahydroxydiphenoyl-D-glucose) (71) proposed that the ( + )-hexahydroxydiphenoyl group had the s-configuration. However OKUDA (62) has very recently correlated (+ )-hexamethoxydiphenic acid (25) from corilagin (28) with the same acid derived from the dibenzocyclo-octane lignan schizandrin (29) whose chirality had been shown to be R by comparison with the X-ray derived molecular structure of the lignan gomisin D (33) (Scheme 7).…”

“…The hypothesis is based on a suggestion that one of the aromatic residues of a bound hexahydroxydiphenoyl group can undergo isomerisation and hydrolytic fission to give the modified residue (48) which is part of the structure of chebulinic acid (56) and chebulagic acid (47). Chebulic acid as it is bound to D-glucose in these acids is in the form (48) but hydrolysis of either compound gives, after lactonisation, free chebulic acid (54). This form of metabolism occurs in the fruit of Terminalia chebula.…”

An X-ray and conformational study of 5,7-dihydro-1,11-dimethyl-6H-dibenzo[a,c]cyclohepten-6-one and its methyl derivatives

“…The bridged biaryl ketone, 5,7-dihydro-1,ll-dimethylL6H-dibenzo[a,c]cyclohepten-6-one, 1, is a chiral derivative of biphenyl whose barrier to racemization was found to be 39 kcal/mol (1,2). A C2 axis passes through the central ring of 1 and along the C--0 bond of the carbonyl group.…”