Abstract

The 60 MHz ¹H NMR spectra of racemic ethosuximide, <i>1,</i> have been studied in detail with the achiral shift reagent, <i>tris</i>(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III), <i>2,</i> and the chiral <i>tris</i>(3-trifluoromethylhydroxymethylene)-<i>d</i>-camphorato]europium(III), <i>3.</i> Enantiomeric shift differences, ΔΔδ, were clearly observed for the CH₃ of the ethyl group of <i>1</i> at molar ratios of <i>3:1</i> as low as 0.0385, with ΔΔδ values of about 12 Hz seen at a <i>3:1</i> ratio of 0.340 for CDCl₃ solutions at 28°, 0.634 molal in <i>1.</i> Smaller ΔΔδ values were also seen for the quaternary methyl and for one of the hydrogens at C-4. Parallel studies with <i>2</i> were performed to support assignments. Results are compared with a group of important drugs that are structurally related, including ethotoin, mephenytoin, glutethimide, methsuximide, phensuximide, and paramethadione, in terms of steric and basicity effects. Correlations of both lanthanide-induced shift (Δδ) and ΔΔδ could generally be made from simple electronic considerations related to infrared carbonyl stretching frequencies. Of the 28 sets of Δδ values assigned for the substrates, <i>3</i> gave significantly larger values than <i>2</i> in only two cases.

Laser action from 2,6,8-position trisubstituted 1,3,5,7-tetramethylpyrromethene-BF₂ complexes: part 1

Theodore G. Pavlopoulos, Joseph H. Boyer, Mayur Shah, Kannappan Thangaraj, and Mou-Ling Soong
Appl. Opt. 29(27) 3885-3886 (1990)

Laser action from 2,6,8-trisubstituted-1,3,5,7-tetramethyl-pyrromethene-BF₂ complexes: part 2

Joseph H. Boyer, Anthony Haag, Mou-Ling Soong, Kannappan Thangaraj, and Theodore G. Pavlopoulos
Appl. Opt. 30(27) 3788_1-3789 (1991)

Infrared Band Assignments for the 2900 cm⁻¹ Region Methyl Group Vibrations in XC₆H₄COOCH₃, XC₆H₄CH₃, and XC₆H₄COCH₃ Molecules

Marie-Thèrèse Forel, Nelson Fuson, and Marie-Louise Josien
J. Opt. Soc. Am. 50(12) 1228-1231 (1960)

Important role of the ethylenedioxy group bound to the thienyl-di-vinylene π-conjugation unit of tricyanofuran-based donor-acceptor electro-optic chromophores

Toshiki Yamada, Isao Aoki, Chiyumi Yamada, and Akira Otomo
Opt. Mater. Express 6(9) 3020-3035 (2016)

Laser action from a 2,6,8-position trisubstituted 1,3,5,7-tetramethylpyrromethene-BF₂ complex: part 3

Theodore G. Pavlopoulos, Joseph H. Boyer, and Govindarao Sathyamoorthi
Appl. Opt. 37(33) 7797-7800 (1998)