Determining the solution state orientation of a Ti enolate via stable isotope labeling, NMR spectroscopy, and modeling studies.
Our group has used Ti-promoted aldol additions with an oxazolidineselone as the chiral auxiliary with much success. In these reactions, the Se atom in the auxiliary both promotes stereospecific addition as well as reports on, through the use of 77Se NMR spectroscopy, the ratio of diastereomers produced and the geometry of intermediates as the reaction proceeds. Through stable isotope labeling and NMR spectroscopy, we are able to experimentally observe a Ti enolate in solution and gain insight into its structure and reactivity. Results from molecular modeling calculations are also presented for comparison with NMR data.
Kimball
David B
DB
NIH Stable Isotope Resource, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Michalczyk
Ryszard
R
Moody
Eddie
E
Ollivault-Shiflett
Morgane
M
De Jesus
Karl
K
Silks
Louis A Pete
LA
D002247:Carbon Isotopes; D007553:Isotope Labeling; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D016566:Organoselenium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010080:Oxazoles / Q000138:chemical synthesis / Q000737:chemistry*; D012643:Selenium; D012996:Solutions; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*
D002247:Carbon Isotopes; D007554:Isotopes; D009942:Organometallic Compounds; D016566:Organoselenium Compounds; D010080:Oxazoles; D012996:Solutions; C064210:oxazolidine; D014025:Titanium; D012643:Selenium