Preparation of Optically Active Cyclic Carbonates and 1,2-Diols via Enantioselective Hydrogenation of α-Methylenedioxolanones Catalyzed by Chiral Ruthenium(II) Complexes
摘要:
The enantioselective hydrogenation of alpha-methylene-1,3-dioxolan-2-ones catalyzed by chiral (diphosphine)ruthenium complexes leads to optically active cyclic carbonates with high enantioselectivities. Their hydrolysis in methanol in the presence of potassium carbonate quantitatively affords optically active 1,2-diols.
Stereocontrolled preparation of tetrahydrofurans from acid-promoted rearrangements of allylic acetals
作者:Mark H. Hopkins、Larry E. Overman、Gilbert M. Rishton
DOI:10.1021/ja00014a030
日期:1991.7
tetrahydrofurans from readily available allylic diol and carbonyl components is reported. This synthesis is highly stereocontrolled and allows carbon side chains to be incorporated at each carbon. Enantiomerically pure tetrahydrofurans are readily prepared from chiral, nonracemic allylic diol precursors. The asymmetric synthesis of (+)-muscarine tosylate from the lactate-derived allylic diol 6a demonstrates that
Synthesis of (R)- and (S)-acetoin (3-hydroxybutan-2-one)
作者:David H. G. Crout、Stephen M. Morrey
DOI:10.1039/p19830002435
日期:——
Two synthetic routes to the enantiomers of acetoin (2) of high optical purity have been devised. One starting from (S)-3-methylbut-3-en-2-ol (9) led to (S)-(+)-acetoin (13). The other, starting from (2R,3R)-butane-2,3-diol gave (R)-(–)-acetoin (16).
Naturally occurring compounds related to phenalenone. Part VII. Absolute configuration of atrovenetin and related compounds
作者:John S. Brooks、George A. Morrison
DOI:10.1039/p19740002114
日期:——
Chemical correlation of a degradation product of isoherqueinone with (–)-(S)-ethyl lactate has established that herqueinone and isoherqueinone have the R- and S-configuration, respectively, at the asymmetric centre in the side-chain; it follows that atrovenetin possesses the R-configuration.
rationalizing their optical properties. The sign of the CD couplets for both the polymer and monomer are just opposite between R and S guests, which suggests that the chirality is dictated solely by the stereogenic projection of the chiral centers. Stronger intra- and intermolecular coupling in the polymeric complexes is responsible for the highly enhanced CD couplets as compared to the monomer and have only
A Chemical/Computational Approach to the Determination of Absolute Configuration of Flexible and Transparent Molecules: Aliphatic Diols As a Case Study
electronic circular dichroism (ECD) spectra, which show several (up to five) Cotton effects in the 350−200 nm range due to valence shell π→π* transitions. These features allow simulation of the chiropticalproperties of these compounds at the TDDFT/B3LYP/6-31G* level of theory to obtain, using the known ACs of these compounds, a satisfactory reproduction of the OR values (sign and order of magnitude; quantitatively