The CD and UV spectra of (2S)-2,2\u27-spirobi[2H-benz[e]indene]-
1,1\u27(3H,3\u27H)-dione (2) and (IR,I\u27S,2S)-I,I\u27,3,3\u27-tetrahydro-2,2\u27-spirobi[
2H -benz[e]indene]-I,I\u27 -diyl diacetate (3) were theoretical1y
calculated by the application of the Jt-electron SCF-CI-DV MO
method. The shape of component CD and UV bands was approximated by method (A) of the Gaussian distribution, or by method (B) employing the observed band shape of the UV spectra of
model compounds. The calculated CD and UV curves were in
good agreement with the observed ones. For compound 2, method
(A), calcd CD, Aox! = 318.5 nm (As = +5.8), 250.0 (-63.7), 213.7
(+90.8); obsd. CD, J"" = 336.2 nm (1\u2711; = +11.9), 253.2 (-96.1), 214.0 (+ 1\u2712.1). For compound 3, method (A), calcd CD, J,e,! = 279.3 nm (As = +6.5), 224.2 (-590.2), 213.7 (+753.7); obsd. CD, J\u27e" = 285.0 nm (As = +4.4), 230.2 (-961.5), 221.6 (+567.1). The absolute stereostructures of chiral spiro aromatics 2 and have been thus established by the calculation. The mechanism of the widely spread and weak CD Cotton effects of diketone 2 has been also clarified by the calculation. The calculated CD and UV spectral curves of compound 3 obtained by the application of method (B) were in
excellent agreement with the observed ones: calcd CD, Ae<t = 282.5
nm (As = +10.2), 231.5 (-1139.5), 221.2 (+474.0); obsd. CD, J,,,! =
285.0 nm (As = + 4.4), 230.2 (-961.5), 221.6 (+ 567.1)
