660849-11-6Relevant articles and documents
Toward the Development of A Structurally Novel Class of Chiral Auxiliaries. Conformational Properties of the Aldol Adducts of Oxadiazinones: Observation of Unusual Shielding Effects
Burgeson, James R.,Renner, Matthew K.,Hardt, Ingo,Ferrence, Gregory M.,Standard, Jean M.,Hitchcock, Shawn R.
, p. 727 - 734 (2004)
Asymmetric aldol reactions were conducted with the titanium enolate of N3-hydrocinnamoyl-3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-one to afford aldol adducts 5a-j. The dominant product of the asymmetric aldol reaction was the non-Evans syn adduct as determined by 1H NMR spectroscopy and X-ray crystallography. When evaluating the 1H NMR spectra of adducts 5a-j, a highly shielded signal with an average chemical shift of 0.05 ppm was observed. This signal was readily determined to be the C5-methyl group of the oxadiazinone. It is presumed that the overall conformation adopted by the aldol adducts in solution places an aromatic ring of the N3-substituent in close proximity to the C5-methyl group. An investigation of this conformational preference is conducted employing 1H NMR spectroscopy, X-ray crystallography, and computational methods.
