Nitroxide Diels-Alder reaction

Recently, the key intermediate 33 was reported to be constructed from d-ribose 36 (Scheme 11), which is widely used as intermediate in pharmaceutics and costly obtained. For the alternative synthesis route of 33, the most intermediates were obtained as solid, which greatly facilitates the isolation and purification of the products. Interestingly, one route targeting deuterated ticagrelor used a nitroxide Diels-Alder reaction with cyclopentadiene to incorporate the amine into the ring system. ... 

Tunca et al. [27, 28,38] reported in a series of papers on a multi-click approach for the preparation of brush copolymers. The backbone consisted of homopolymers, statistical polymers, or block copolymers from ONBEs with orthogonal side groups for Diels-Alder click reaction [27,28,38], azide/alkyne click reaction, [27, 28, 38] and nitroxide coupling [27]. In a grafting-to approach, maleimide-or ONBE-functionalized polymers (PEG, P BA, PMMA (56)) were attached by Diels-Alder click reaction with the anthracene groups pendant at the polymer backbone (55) (Scheme 9.8b). PCL chains were attached by an azide/alkyne click reaction, while a combination of Diels-Alder and azide/alkyne click reaction allowed the synthesis of graft copolymers with PS-/ -PEG-, PS-h-PMMA-, or PS-/ -P BA side chains. 

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