Circular dichroism octant rule

The -position of the cyclopropane ring was established by the observed negative circular dichroism curve (Ae — 2.03 in dioxane at 298 m/i) and consideration of the inverse octant rule for cyclopropyl ketones. ... 

D. A. Lightner, The octant rule, in Circular Dichroism Principles and Applications, 2nd edn, Wiley-VCH, New York, 2000. 

In Ref 105 the (n, n ) circular dichroism of the tricyclic ketones 152-155 was analyzed with the aim to see whether the systems must be viewed as inherently chiral chromophores or rather inherently symmetric chromophores, respectively. If they fall more nearly into the inherently symmetric classification the octant rule should be applicable. As a basis for the classification the order of magnitude of the rotational strengths was used together... 

Hgura 10 The octant rule. (Source Circular dichrorsm and linear dichroism, A. Rodger and 6. Norden, 1997, by permission of Oxford (Jrilversity Press.)... 

Of all the physical methods commonly in use in chemistry and biochemistry, circular dichroism (CD) is probably the most underused. The method has great potential but probably due to the still-empirical nature of many of the rules, there tends to exist a large psychological barrier to its daily use. These empirical rules, the most well-known of which is the octant rule (274), are valid for particular sets of compounds and yield invaluable information (192) if applied with care. In the... 

There is already substantial experimental evidence and theoretical justification for electronic interaction between cyclopropyl and carbonyl groups. A charge-transfer band in the vapour-phase u.v. spectra of several cyclopropyl ketones has been detected at ca. 180 nm (s ca. 4000). The circular dichroism of several optically active cyclopropyl ketones, together with conformational analysis based upon n.m.r. spectroscopy results and INDO theory, has been used to extend the octant rule for such compounds. ... 

Snatzke has extended the useful analysis of the effect of 3-substituents upon the circular dichroism of adamantanones and substituted bicyclo[3,3,l]-nonan-9-ones. With earlier studies the effect of a wide range of substituents is now established, and the failure of the octant rule to account for the observed results is clear, but a satisfactory general analysis of substituent effects is still awaited. 

Lightner DA. The octant rule. In Berova N, Nakanishi K, Woody RW, editors. Circular dichroism principles and applications. 2nd ed. New York Wiley-VCH 2000. p 261-304. 

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