Determination of enantiomeric purity of chiral lactones. A general method using nuclear magnetic resonance

A stereocontrolled synthetic entry to the primary prostaglandins from butadiene. Oxy anionic substituent effects on [1,5]-hydrogen sigmatropy

“…BuaSnH, toluene, 80 °C) with 95% efficiency. Exposure of 15 to 3 equiv of methyllithium afforded diol16 which was directly subjected to NMR examination (CDCI3 solution) 23. In the presence of ~30 mol % of tris[(trifluoromethyl)hy-droxymethyIene-if-camphorato]europium(III), the diastereotopic methyl groups appear as two equally intense sets of twinned singlets at 4.0, 3.8,2.7, and 2.5, sufficiently separated for accurate integration.…”

Selective Reductions. 59. Effective Intramolecular Asymmetric Reductions of α-, β-, and γ-Keto Acids with Diisopinocampheylborane and Intermolecular Asymmetric Reductions of the Corresponding Esters with B-Chlorodiisopinocampheylborane

“…In contrast, we expected smooth intramolecular reduction of β-keto acids with 2. The reduction of benzoylacetic acid (16) with 2 was complete within 55 h, and alkaline H 2 O 2 workup provided the product hydroxy acid 17 in 85% yield (eq 7). The optical rotation revealed that we had obtained the (S)hydroxy acid in 92% ee.…”

Syntheses of Optically Active Verrucarinic Acid. 40th Communication on Verrucarins and Roridins

“…These data were in good agreement with the results of a 'H-NMR. analysis of the diol20 (obtained with MeLi) in the presence of ELI ( t f~)~ [26] as well with that of a capillary GC.-analysis of the orthoester 21 which was prepared with (2 R, 3 R)-butan-2,3-diol [27]. The two latter measurements indicated an e.e.…”