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Artificial Molecular Rotors

“…More comprehensive treatments of the static and dynamic stereochemistry of alkyl groups can be found in several reviews. ,,, Other systems, such as tetraalkylethylenes, tetracycloalkylethylenes, tetracycloalkylmethanes, ortho -disubstituted benzenes, , alkylated propenals, alkylated adamantanes, and 8-(dimethylamino)naphthyl ketones, have also been studied for correlated rotation of the alkyl or related fragment. A number of groups have also investigated cogwheeling of alkyl groups from a computational standpoint. − Pophristic and Goodman calculated the “gearing” (correlated disrotation) and “antigearing” (rotation in phase) in dimethyl ether. They found that the splitting between the geared rotation and antigeared rotation is due to hyperconjugative effects instead of simple steric factors.…”

“…A number of groups have also investigated cogwheeling of alkyl groups from a computational standpoint. [309][310][311][312] Pophristic and Goodman 313 calculated the "gearing" (correlated disrotation) and "antigearing" (rotation in phase) in dimethyl ether. They found that the splitting between the geared rotation and antigeared rotation is due to hyperconjugative effects instead of simple steric factors.…”

An Example of Ketone Olefination via Praseodymium-Mediated Barbier Reaction in the Presence of Diethyl Phosphite

“…However, the need for ylides, which were generated by a stepwise procedure, could not be avoided in these reactions. Accordingly, Wong 6 and Hopf 7 afforded conjugated diene utilizing an elimination reaction mediated by strong base. Moreover, several reactions employing Ni, 8 Pd, 9 and Ru 10 complexes have been used to synthesize conjugated alkenes; however, although this strategy is useful, it is less practical because of the use of precious metal.…”

(E)-2,2,6,6-Tetramethylhept-4-en-3-one

“…In our studies of the stereochemistry, stability and chemical properties of tert-butylated oligo-and polyolefins (Hopf et al, 1998), we prepared a sample of the title compound, (3), a known ,-unsaturated ketone (Dimroth & Mach, 1968). We present here its structure.…”