Application of Wallach's Rule in a Comparison of the X-ray Crystal Structures of the Racemate and the (S) Enantiomer of (1-Hydroxy-3-phenyl-2-propenyl) Dimethylphosphonate

Abstract

The crystal structures of the racemate and the (S) enantiomer of (1-hydroxy-3-phenyl-2-propenyl) dimethylphosphonate, C11H15O4P, were determined by X-ray diffraction. The crystal density of the racemate was found to be 6.2% greater than the crystal density of the (S) enantiomer. In both crystal structures the molecules form chains by hydrogen bonding between the OH of one molecule and the P=O of another. Observed differences in atomic displacement between the two structures are discussed in view of the C—H...O interactions.

Reevaluating the Stability and Prevalence of Conglomerates: Implications for Preferential Crystallization

“…The high prevalence rate of heterochiral crystals has been justified in the past using Wallach’s rule, which states that heterochiral crystals pack more densely than their homochiral counterparts, coupled with an assumed correlation between density and stability. , However, previous investigations of the validity of Wallach’s rule found mixed results, ,− and the claim that density and stability are directly related has also come under scrutiny in the literature. ,, In this work, the validity of Wallach’s rule and the relationship between density and stability are re-examined.…”

Enantioselective Inhibition of Microbial Lipolytic Enzymes by Nonracemic Monocyclic Enolphosphonate Analogues of Cyclophostin

“…The absolute configurations of the 1-(dimethoxyphosphoryl)allyl methyl carbonates 4 ( R ) and 4 ( S ) were unambiguously assigned by conversion to the well-characterized enantiomers of ( E )-1-(dimethoxyphosphoryl)-3-phenylallyl methyl carbonate 5 ( R ) and 5 ( S ) by Grubbs cross metathesis with styrene. Furthermore, the UV absorbing enantiomers of 5 were easily separable on a chiral stationary phase, allowing the enantiomeric excess (>95% ee ) to be determined. , …”

“…Furthermore, the UV absorbing enantiomers of 5 were easily separable on a chiral stationary phase, allowing the enantiomeric excess (>95% ee) to be determined. 24,25 With the fact that both the absolute configuration on the asymmetric carbon and the enantiomeric excess of the starting phosphonate are preserved upon cross metathesis reaction, 22 the resulting phosphono allylic carbonate 6 therefore displays the same (R) configuration with comparable ee to the carbonate 4(R). Palladium(0)-catalyzed reaction of the carbonates 6 with methyl acetoacetate gave the vinyl phosphonates 7 as a 1:1 diastereoisomeric mixture related to the new acetoacetate carbon stereocenter thus formed.…”