Circular dichroism of some cyclopropane ring containing 1,3-cyclo-5,10-seco-steroidal ketones

Circular dichroism of the rearranged keto steroids 3 and 4, containing a condensed three and nine-membered ring system, shows that the conformation of the nine-membered ring is the same in solution as in the crystal; reduction of the kto group does not change this situation. CD also indicates that epimerization at C(5) in the pair $\text{7}\text{8}$ and the pair $\text{11}\text{12}$ leaves the cyclononanone ring conformation unchanged.     

Circular dichroism—LXIX: Correlation between the stereochemistry of amino steroids and chiroptical properties of their unidentate copper(II) succinimidate complexes

The complexes of formula [CuSu₂Am₂^*] formed in situ from amino steroids (Am^*) and a methylene chloride solution of the complex [CuSu₂Pr₂] (Su: succinimidate; Pr: isopropyl amine) show in the range of the d-d bands two Cotton effects at approx. 700 (Band I) and 600 nm (Band II), whose signs are correlated with the preferred torsion angle of the H₂N-Cu moiety: a positive torsion angle leads to a positive CD-band I and to a negative CD-band II. These complexes form useful Cottonogenic derivatives of primary amino compounds.     

Die absolute Konfiguration von Carquejol und verwandten o-Menthan-Derivaten

The structure of carquejol is amended to that of cis-3-hydroxy-o-mentha-1(7),4,8-triene; the chirality has been confirmed as 2 R, 3 S by correlation with the (?)-cis-o-menthane obtained from carquejol and that from (+)-verbenene of known absolute configuration. The two double bonds of the dihydrocarquejol system ( 15 and 16 ) constitute a helical system, that especially in the case of the acetate ( 16 ) fixes the isopropenyl group in such a way that a very high Δ? value in the CD. curve is observed. The conformational significance of this phenomenon is discussed.     

Chiroptische Eigenschaften und absolute Konfiguration von 9, 9′-Spirobifluoren-Derivaten

The circular dichroism and optical rotatory dispersion of three vespirenes, three vespirones, and of some related 9, 9′-spirobifluorene derivatives [4] have been measured. The absolute configurations of these compounds have been determined from chiroptical properties (CU., ORD.) in four ways which give mutually consistent results. For the (?)-vespirenes the (R)-configuration (Figs. 1 and 2) follows from 1 is treatment.     

Circular dichroism—LVII : Chiroptical properties of some α-halo- propionanilides

The CD of the anilides of α-halo-propionic acids depends on solvent and substitution of the aromatic ring. Changes of the CD with solvent can be explained by taking into account three conformers (G, A⁺ and A^? of Fig 1). The CD band around 250 nm is negative for derivatives of the l-acids in all solvents except hydrocarbons in which it is positive. The ¹L_b band Cotton effects are very weak or not observed. The ¹L_a—CD band is much stronger in the m- and o-substituted anilides than in-the p- or unsubstituted anilides.     

Circulardichroismus. 62. Mitteilung. Chiroptische Eigenschaften einiger Trimethylcyclohexen-Derivate: Die Jonone,Irone und Abszisinsäuren

The absolute configuration of (+)-α-ionone 3 (R), the absolute configurations at C(6) of (+)-cis-α-irone 5 (6S) and (?)-trans-α-irone 6 (6R), and the absolute configurations of (+)-cis-abscisic acid 10 (S) and (+)-trans-abscisic acid 11 (S) are deduced from the CD.-spectra.     

Circular dichroism—LXIII : Third-sphere contribution to the R-band cotton effect of lactones

The Cotton effect within the n→π* band of the lactone chromophore of the halo lactones 3a-c, prepared from (1S)-2-bromo adamantanedione-4.8 (1) is positive and can be used to determine unequivocally the sign of third-sphere contributions of the appropriate sector rule. An “axial” halogen (Cl, Br, I) substituent in a β-position to the keto group of these halogeno oxa-homoadamantanediones gives an antioctant contribution to the Cotton effect of the carbonyl chromophore as observed earlier for the corresponding halogeno-adamantanones.     

Steroids and sex hormones. 252. Chiroptical properties of some C(5) stereoisomeric 3-oxo-4,4-dimethylsteroids

The chiroptical properties of the C(5)-epimeric 4,4-dimethyl-steroidderivatives 6 , 7 and 8 , recently prepared [1], are reported.