The chemoselective synthesis of amides by decarboxylative couplings of alpha-ketoacids and isoxazolidines makes possible an iterative approach to poly-beta3-peptides. Peptide assembly occurs under aqueous conditions and requires no coupling reagents. The requisite isoxazolidine monomers are prepared in enantiopure form by a convenient two-step protocol starting from the appropriate aldehydes.

in recent years there has been considerable interest in the synthesis and separation of enantiomers of organic compounds especially because of their importance in the biochemistry and pharmaceutical industry. high-performance liquid chromatography is a very useful method for the direct separation of enantiomers. however, about 30−40 years ago, commercially available chiral stationary phases wer...

In the title compound, C17H28N2O3, the isoxazolidine ring adopts an envelope conformation with the O atom deviating from the mean plane of the other four ring atoms by 0.617 (1) Å. In the crystal, mol-ecules are linked via weak C-H⋯O hydrogen bonds, forming chains which extend along the b-axis direction.

In recent years there has been considerable interest in the synthesis and separation of enantiomers of organic compounds especially because of their importance in the biochemistry and pharmaceutical industry. High-performance liquid Chromatography is a very useful method for the direct separation of enantiomers. However, about 30−40 years ago, commercially available chiral stationary phases wer...

The regioselective intramolecular 1,3-dipolar cycloaddition of the phenylsulfonylallene-nitrone derivatives has been developed. This reaction showed that the distal double bond of the allene exclusively reacted with the nitrone group to produce the bicyclic isoxazolidine derivatives regardless of the substitution pattern on the allenyl moiety.

[Structure: see text] Enantioselective nitrone cycloadditions with beta-substituted alpha,beta-unsaturated 2-acyl imidazoles catalyzed by bis(oxazolinyl)pyridine-cerium(IV) triflate complexes 1 have been reported. The isoxazolidine products were efficiently transformed into densely functionalized beta'-hydroxy-beta-amino acid derivatives.

one of the problems encountered in ce separations of basic compounds is the adsorption of analytes onto the negatively charged capillary wall which could lead to poor repeatability of migration time and peak area. additionally, separation of enantiomers of chiral of basic drugs is commonly carried out in low ph buffer which contributes to strong ionic interaction of the cationic drug ions with ...

In the title compound, C(17)H(19)NO(3), the isoxazolidine ring adopts an envelope conformation with the O atom as the flap. In the crystal, O-H⋯O hydrogen bonds form C(2) (3)(14) R(2) (2)(14) motifs.

In the title compound, C(14)H(16)BrNO(5), the isoxazolidine ring adopts an envelope conformation, with the N atom at the flap. In the crystal, inter-molecular C-H⋯N and C-H⋯O hydrogen bonds generate R(3) (3)(18) ring motifs which are fused into a ribbon-like structure extending along the b axis.

The β-amino acid antibiotic (+)-negamycin has been synthesised in ten steps from epichlorohydrin via Sakurai allylation of an isoxazolidine intermediate. The key allylation reaction proceeded with complete trans-selectivity, which is attributed to electrostatic attraction between the chlorine atom and the iminium ion in the Sakurai intermediate.