Resolution, circular dichroism spectrum, molecular structure, and absolute configuration of cis,trans-1,3-cyclooctadiene

Refined model of optical activity of cis‐dihydrodiol metabolites: Role of 1,3‐diene conformation in the electronic circular dichroism spectra

“…This seems correct as long as the structural constraints do not force the CC bond(s) out of planarity. A distorted trans‐disubstituted CC bond in cis,trans ‐1,3‐cyclooctadiene was considered as the main source of its optical activity 30. It has been shown that the rotatory strength for the π–π* electronic transition of twisted (−10°) ethylene molecule is of the order 75–198 × 10 −40 cgs units, depending on the calculation method used 31.…”

Polysaccharide-Based Chiral LC Columns

“…5. [19][20][21][22][23][24][25][26][27] Most commercialized polysaccharide-based CSPs have been prepared by coating them on silica gel. When CTA-I was coated from a solution, the CTA afforded another useful CSP (OA in Fig.…”

Optically Active (E,Z)-1,3-Cyclooctadiene: First Enantioselective Synthesis through Asymmetric Photosensitization and Chiroptical Property

“…E -Isomers of medium-sized cycloalkenes have long aroused much theoretical, spectroscopic, synthetic, and physicochemical interests because of their constrained, chiral molecular structures as well as enhanced thermal and photochemical reactivities, − arising from the distorted π orbital and the hindered rope-jumping motion of the methylene chain bridging the double bond. However, only eight-membered cyclic E -isomers have been demonstrated unequivocally to be chiral with moderate thermal stability at ambient temperatures, and their chiroptical properties have been well documented. − ,, On the other hand, smaller-sized ( E )-cycloalkenes, which should be chiral, are merely known as unstable transient species, while the larger ones have been revealed to racemize spontaneously at room temperature . In this context, ( E,Z )-cyclooctadienes are intriguing as borderline cases.…”

“…In spite of the thermal and photochemical syntheses of 1EZ reported by Cope et al and Liu, its chiroptical properties have not been investigated experimentally 8 or theoretically 19 until recently, probably due to the thermal instability and the lack of convenient enantioselective synthetic methods. Isaksson et al reported that racemic 1EZ can be resolved optically by chiral HPLC over triacetylcellulose to give optically active 1EZ of >90% enantiomeric excess (ee). This sample was reported to show large specific rotation and circular dichroism: [α] 20 D −649° ( c 0.017, ethanol), Δε −8.83 M -1 cm -1 (λ ext 230.5 nm, ethanol) .…”

“…Isaksson et al reported that racemic 1EZ can be resolved optically by chiral HPLC over triacetylcellulose to give optically active 1EZ of >90% enantiomeric excess (ee). This sample was reported to show large specific rotation and circular dichroism: [α] 20 D −649° ( c 0.017, ethanol), Δε −8.83 M -1 cm -1 (λ ext 230.5 nm, ethanol) . Since the two CD peaks at 230 and <190 nm gave the same (negative) sign inconsistent with the prediction of the diene helical rule, they attempted to determine the absolute configuration of 1EZ by CNDO/S-CI calculation and tentatively assigned the (−)-form as possessing the P helicity or R configuration .…”