An NMR Method for Assigning Relative Stereochemistry to β-Hydroxy Ketones Deriving from Aldol Reactions of Methyl Ketones

Abstract

We describe a simple 1H NMR analysis that permits the stereochemistry of beta-hydroxy ketones to be assigned by visual inspection of the ABX patterns for the alpha-methylene unit of the beta-hydroxy ketone in the 1H NMR spectra. This method has been verified by application to a wide range of beta-hydroxy ketones deriving from aldol reactions of chiral aldehydes with a variety of chiral and achiral methyl ketone enolates (see Tables 1 and 2). The stereochemistry of 54 of these compounds have been assigned by rigorous chemical methods.

Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos

“…Nos exemplos exibidos no Esquema 21, a determinação da estereoquímica relativa dos adutos de aldol 90-93 foi realizada através da análise das constantes de acoplamento para os hidrogênios α-carbonila, utilizando o método de Roush 56,57 .…”

The Isolation and Structure Elucidation of Tasiamide B, a 4-Amino-3-hydroxy-5-phenylpentanoic Acid Containing Peptide from the Marine Cyanobacterium Symploca sp.

“…Thus 1 was composed of the following fragments: Ala, Leu, Val, iV-Me-Phe, iV-Me-Gln, lactic acid, Ahppa, and O-Me-Pro. 10.1021/np030114z CCC: $25.00…”

Stereoselective Synthesis of the Monomeric Unit of SCH 351448

“…The following boron mediated Table 1. J (H a /H b , H β ) in γ-methyl-β-hydroxy ketones from Roush et al [14] syn-Felkin…”

“…The stereochemical assignment of the anti-Felkin configuration in 28 was possible according to the NMR-analysis of Roush et al [14] Table 1 shows representative chemical shifts and coupling constants for γ-methyl-β-hydroxy ketones. The experimental data for 28 are J(H b H β ) = 9.5 Hz and J(H a H β ) Ͻ 2.5 Hz and thus indicate the anti-Felkin configuration.…”