Octant dissignate

An empirical estimation of the sign and magnitude of As of (—)-quadrone (73) indicated that strain effects and octant-dissignate contributions of the pseudoaxial a-hydrogens dominate the CD spectrum of 73172. 

Circular dichroism measurements on R-(+)-2-methyl-l-tetralone have shown that it adopts a sofa conformation with a pseudo-equatorial methyl group. From a detailed study ° of the c.d. of chiral cyclopentanones and related compounds the 71 M band data suggest that C,—H bonds make dominant contributions in the octant-dissignate anti-octant sense. The magnitude of a —H contribution is... 

The anti-octant or dissignate behavior of deuterium was discussed earlier (Section II.F), and it operates as expected in compounds 8-10. The octant representations... 

An octant projection diagram predicts a dissignate halogen contribution in the C(5) halogen-substituted bicyclo[2.2.1]hept-5-en-2-ones (125 and 126), and a consignate... 

The ring carbons of the rra/u-4-ketodecalin (e) lie in the same back octants as the tratis-1 -decalone (a), so these perturbers should sum to a (-) contribution to the CD. The only difference between (e) and (a) is the /3-axial methyl in the former, which is known from earlier work on adamantanones (see preceding section) to be a weak dissignate perturber (in this case a weak (+) contributor). The observed negative CE of (e) is only slightly smaller than that of (a). 

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