ChemInform Abstract: Stereochemical Studies of Some 12a‐Substituted Rotenoid Derivatives.

Abstract

Stereochemical Studies of Some 12a-Substituted Rotenoid Derivatives.-The absolute configuration of some title compounds like (I) and (II) is determined by means of 1H NMR, CD and molecular mechanics studies. -(KOSTOVA, I.; BEROVA, N.; IVANOV, P.; MIKHOVA, B.; RAKOVSKA, R.; SNATZKE, G.; Croat.

Isolation of Bioactive Rotenoids and Isoflavonoids from the Fruits of Millettia caerulea

“…The absolute configuration of rotenone (a cis rotenoid containing a C-7 furan-fused 2-methyl-3-O-1-buten-4-yl unit, termed here as a "rotenone-like" rotenoid) was established initially as (2S,3S,2″R) by analysis of exhaustive ozonolysis, oxidation, and degradation reactions [28], and confirmed by investigation of the ECD spectra of rotenoid and isoflavan compounds [29]. A further extensive ECD study showed that rotenone displays pronounced negative CEs at 209 and 276 nm and a positive CE at 237 nm, and a relatively weak negative CE at 307 nm and positive CEs at 333 and 352 nm, with those of its 2,3-di-epimer exhibiting CE bands of opposite signs [30]. A sign inversion of the CEs above 300 nm was observed in "cis-3-hydroxyrotenone-like" rotenoids [20,30], and a CE sign inversion below 300 nm was found in cis "deguelin-like" rotenoids (rotenoids containing a C-7 pyranfused 3-methyl-3-O-1-buten-1-yl unit) [31,32].…”

“…A further extensive ECD study showed that rotenone displays pronounced negative CEs at 209 and 276 nm and a positive CE at 237 nm, and a relatively weak negative CE at 307 nm and positive CEs at 333 and 352 nm, with those of its 2,3-di-epimer exhibiting CE bands of opposite signs [30]. A sign inversion of the CEs above 300 nm was observed in "cis-3-hydroxyrotenone-like" rotenoids [20,30], and a CE sign inversion below 300 nm was found in cis "deguelin-like" rotenoids (rotenoids containing a C-7 pyranfused 3-methyl-3-O-1-buten-1-yl unit) [31,32]. All positive CEs below 300 nm were observed in "trans-3-epi-hydroxydeguelinlike" rotenoids [19].…”

“…Thus, the longer wavelength CE around 350 nm arising from the n→π* transition of the acetophenone chromophore, as indicated by a UV absorption maximum at ca. 246 nm [2,15], and the CE around 320 nm due to the aromatic π→π* transition of the B-ring can be regarded as indicative of the absolute configuration of 3hydroxyrotenoids [30,33]. The cis nature of 1 was indicated from its H-6′ chemical shift at δ H 6.56 (l " Table 1) [22][23][24][25], and the absolute configuration was defined as (2S,3S), based on its positive CEs at 203, 218, and 299 nm and negative CE bands at 257 and 366 nm observed in the ECD spectrum (l " Fig.…”

An Intramolecular CAr–H•••O=C Hydrogen Bond and the Configuration of Rotenoids

“…The electronic circular dichroism (ECD) spectra of rotenone and several analogues have been investigated, with the Cotton effects (CEs) characterized [19, 30]. Although the CEs above 300 nm were not suggested as reliable configurational assignments for some 3-substituted rotenoids [31], it has been well documented that these CEs are suitable for indicating the absolute configuration at C-2 and C-3 of 3-hydroxyrotenoids [19, 32]. …”