1. Chiroptical properties of the ketene and diazo chromophores. Part 2.1 Dissymmetric perturbing influence of α-alkyl substituents on the n–π* transitions in cyclic dialkylketenes and 2-diazoalkanes vs. cyclic ketones Gennady V. Shustov,Fang Sun,Ted S. Sorensen,Arvi Rauk J. Chem. Soc. Perkin Trans. 2 1999 1035