- Progress toward a rationally designed, chemically powered rotary molecular motor
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Building on prototype 1, which achieves 120° of phosgene-powered unidirectional rotation to rotamer 6 (see Figure 5 in the full article), 7 was designed to accomplish repeated unidirectional rotation (see Scheme 7). Compound 7 contains an amino group on each blade of the triptycene and a 4-(dimethylamino)pyridine (DMAP) unit to selectively deliver phosgene (or its equivalent) to the amine in the "firing position". The synthesis of 7 is described: the key constructive steps are a benzyne addition to an anthracene to generate the triptycene, a stilbene photocyclization to construct the helicene, and a Stille coupling to incorporate the DMAP unit. The DMAP unit was shown to regioselectively relay 1,1′-carbonyldiimidazole (but not phosgene) to the proximal amino group, as designed, but rotation of the triptycene does not occur. Extensive attempts to troubleshoot the problem led to the conclusion that the requisite intramolecular urethane formation, as demonstrated in the prototype (1 → 4), does not occur with 7 (to give 85) or 97 (to give 100). We speculate that either (i) hydrogen bonding between the hydroxypropyl group and functionality present in 7 but absent from 1 or (ii) a Buergi-Dunitz (or similar) interaction involving the DMAP (see 106) prevents achievement of a conformation conducive to intramolecular urethane formation.
- Kelly, T. Ross,Cai, Xiaolu,Damkaci, Fehmi,Panicker, Sreeletha B.,Tu, Bin,Bushell, Simon M.,Cornella, Ivan,Piggott, Matthew J.,Salives, Richard,Cavero, Marta,Zhao, Yajun,Jasmin, Serge
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p. 376 - 386
(2008/04/18)
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- Heteroarylnaphthalenes as inhibitors of leukotriene biosynthesis
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Compounds having the formula I: STR1 are inhibitors of leukotriene biosynthesis. These compounds are useful as anti-asthmatic, anti-allergic, anti-inflammatory, and cytoprotective agents. They are also useful in treating angina, cerebral spasm, glomerular nephritis, hepatitis, endotoxemia, uveitis and allograft rejection and in preventing the formation of atherosclerotic plaques.
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