Unambiguous Determination of the Absolute Configurations of Acetylene Alcohols by Combination of the Sonogashira Reaction and the CD Exciton Chirality Method ? Exciton Coupling between Phenylacetylene and Benzoate Chromophores

Faulknerynes A−C from a Bahamian Sponge Diplastrella sp.: Stereoassignment by Critical Application of Two Exciton Coupled CD Methods

“…In turn, this predicts ( R )- 1 will exhibit a positive Δε in the CD spectrum. Harada has described similar arguments and assignments of alk-1-yn-3-ols by ECCD after a two step derivatization – Sonogashira coupling with a terminal acetylene with an aryl iodide followed by esterification of the secondary alcohol to the corresponding arene-yne benzoate and measurement of CD spectra 19. The sign of the resulting split CE’s conform to the rule, however, the major limitation of the method is its applicability to terminal acetylenes, only.…”

“…24 Nevertheless, as noted by Nakanishi and co-workers,15 only the sign of the long-wavelength component is necessary and sufficient to assign allylic benzoates which also applies for propargylic naphthoates due to the stronger oscillator strength of the 1 B b transition. Even acyclic non-conjugated propargylic O -naphthoates should be amenable to chiroptical analysis , unlike the corresponding O -benzoates that show only weak or non-detectable ECCD from the shorter wavelength acetylene chromophore (< λ 190 nm) ,19. This is demonstrated in the CD spectrum of 15a (Figure 6) which displays a weaker, yet still prominent positive component [λ 240 nm (Δε +4.6)] of the biphasic Cotton effect.…”

Determination of optical purity and absolute configuration of natural 12‐hydroxystearic acid by the 1H NMR anisotropy method

“…Therefore, it is necessary to determine the absolute configuration and the optical purity. Recently, our group reported chiral, 2-methoxy-2-(1-naphthyl)propionic acid (MaNP acid) 1, as novel chiral auxiliary which is a powerful molecular tool for optical resolution and unambiguous determination of the absolute configuration in various alcohols [10][11][12][13][14][15]. These methods can be generalized to a variety of secondary alcohols to synthesize enantiopure alcohols.…”

Synthesis of Bioactive Speciosins G and P fromHexagonia speciosa

“…The spectroscopic data corresponded to the literature data. 2 2-(3-Hydroxyprop-1-yn-1-yl)benzene-1,4-diol (23). Compound 8 (20 mg, 0.079 mmol) in MeOH (1 mL) was placed in a flame-dried round-bottomed flask under an argon atmosphere, and HCl [33%] (10 μL) was added to the solution.…”