Selective control, diene units

Mataka and coworkers reported the studies of the Diels-Alder reactions of [3.3] orthoanthracenophanes 96 and 97, of which anthraceno unit, the potential diene, has two nonequivalent faces, inside and outside. The reactions of 96 with dien-ophiles gave the mixtures of inside and outside adducts with the ratios between 1 1 and 1 1.5. However, the ratio changes drastically, in favor of the inside adducts, when 97 reacts with dienophiles such as maleic anhydride, maleimide and naphto-quinone [55] (Scheme 46). Mataka suggested that the Jt-facial selectivity is controlled by an orbital interaction between the electron-poor dienophiles and the Jt-orbital of the facing aromatics, which would lead to a stabilization of the transition state, while Nishio suggested that the selectivity is due to the attractive k/k or CH/jt interaction [53]. 

Functionalized copolymers from dienes and p-alkylstyrenes can serve as dispersants and viscosity index improvers. The functionalities are introduced via the aromatic units [233,234]. The polymers are selectively hydrogenated to produce polymers that have highly controlled amounts of unsaturation, permitting a highly selective functionalization. The dispersant substances may also include a carrier fluid to provide concentrates of the dispersant. 

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