Enantioselective separations by capillary GC on derivatized cyclodextrins. Part 2: Determination of enantiomeric excess of some racemic 2,3-isopropylidene-1,2,3-cyclohexanetriol derivatives on permethyl α-, β-, and γ-cyclodextrins

Capillary GC on permethyl α-, β-, and γ-cyclodextrins has been applied to separate and quantify the enantiomers of some 2,3-iso-propylidene-1,2,3-cyclohexanetriol derivatives. Quantitative CGC data are compared to those obtained with chiral shift ¹H NMR.     

The Azo(Azoxy) Functionality as a π2 Component in Photo [2+2] cycloadditions ‘syn’- and ‘anti’-3,4-diazatricyclo[4.2.2.22,5]dodeca-3,7-diene,syntheses, photolyses,X-ray-structure analysis,and PE spectra

The propensity of the N?N bond to undergo photo [2 + 2] cycloadditions has been further explored. In the specifically designed 1,5-azo/enes 1–3 , no [2 + 2] cycloaddition has been observed upon either direct or sensitized excitation with light of various wave lengths at temperatures down to 77 K, in line with expectations based on X-ray ( 1 : d = 2.71 Å, ω = 129°) and PE measurements ( 1 : I₁ = 8.0₀, I₂ = 9.0₅ eV; 2 ; I₁ = 8.0₀, I₂ = 9.2₅eV). The steric/stereoelectronic demands for the participation of the N?N bond in pericyclic reactions are clearly more stringent than those for the C?C bond.