A chiral 1,4-oxazin-2-one: asymmetric synthesis versus resolution, structure, conformation and VCD absolute configuration

Absolute configuration determination of chiral molecules in the solution state using vibrational circular dichroism

“…80 Here again, the solvent is CDCl 3 and only one significant low-energy conformer was found. The experimental IR and VCD spectra of (+)-2 were obtained at 4 cm À1 and 2 h collection time for a 0.4 M CDCl 3 solution, and the IR and VCD spectra of (R)-2 were calculated using DFT/6-31G(d)/B3LYP.…”

“…78 Our group has also collaborated with laboratories worldwide on the use of VCD to determine absolute configuration and solution-state conformations. Recent publications include stereochemical analyses of a chiral oxathiane, 79 a chiral 1,4-oxazin-2-one, 80 a vasopressin receptor antagonist, 81 mirtazepine, 82 and (R)-(+)-1-(9-phenanthryl)ethylamine. 83 From our laboratory at Syracuse University, the first VCD calculations on transition metal complexes, (+)-tris(ethylenediaminato)cobalt(III) 41 and Zn sparteine complexes have been published recently.…”

Stereodifferentiation in a Chiral 1,4-Oxazin-2-one Derived from 2-Hydroxy-2-methyl-1-tetralone − A Reagent for Deracemization of Amino Acids

“…[2] Reactions were monitored by TLC on Merck glass plates with 60 F 254 silica gel. Silica gel Si 60 (40Ϫ60 µm) from Merck was used for chromatographic purification.…”

“…Alkylation of 3-methyl-1,4-oxazin-2-one (5a) occurs with high levels of conversion (82 to 100%), total diastereoselectivity, and only a small amount of O-alkylation, thus providing a three-step During work on the synthesis of unnatural amino acids [1] we prepared and determined the absolute configuration of the chiral 1,4-oxazin-2-one 1, [2] which was easier to obtain than the similar literature compounds 2 [3] and 3. [4] Moreover, the corresponding chiral hydroxy ketone 4, which could be recovered and reused, was easy to handle.…”

Efficient synthesis of 2-alkyl-2-hydroxy-6-X-1-tetralones

“…Unfortunately, this synthesis is accompanied by the formation of dimethylated product, which needs to be separated from monomethylated one (with very similar R f ) by column chromatography 5 . Another method leading to almost quantitative yield of 2-metyl-1-tetralone (2) is the reaction using bulky and expensive phosphazene base for abstraction of the proton from 1-tetralone 2 . Recently we published another suitable method for preparation of 2 via Friedel-Crafts reaction of benzene with α-methyl-γ-butyrolactone 6 .…”