Reaktionen mit phosphororganischen Verbindungen. XLI[1]. Neuartige synthetische Aspekte des Systems Triphenylphosphin-Azodicarbonsäureester-Hydroxyverbindung
作者:Hans Loibner、Erich Zbiral
DOI:10.1002/hlca.19760590622
日期:——
New preparative methods using triphenylphosphine-diethyl-azodicarboxylate-hydroxycompound.
使用三苯基膦-二乙基-偶氮二羧酸酯-羟基化合物的新制备方法。
Development of a Catalytic Platform for Nucleophilic Substitution: Cyclopropenone-Catalyzed Chlorodehydration of Alcohols
作者:Christine M. Vanos、Tristan H. Lambert
DOI:10.1002/anie.201104638
日期:2011.12.16
Cyclopropenone makes the switch: 2,3‐Bis‐(p‐methoxyphenyl)cyclopropenone is a highly efficient catalyst for the chlorodehydration of 20 diverse alcohol substrates (see scheme; X=Cl). With oxalyl chloride as catalytic activator, this nucleophilicsubstitution proceeded through cyclopropenium‐activated intermediates and resulted in complete stereochemical inversion in substrates with chiral centers.
环丙烯酮起到了作用:2,3-双(对甲氧基苯基)环丙烯酮是一种高效的催化剂,可对20种不同的醇底物进行氯脱水(参见方案; X = Cl)。用草酰氯作为催化活化剂,这种亲核取代过程通过环丙烯活化的中间体进行,并导致具有手性中心的底物完全立体化学转化。
Steroids. Part IX. The catalytic hydrogenation of 3α-substituted Δ<sup>5</sup>-steroids
作者:J. R. Lewis、C. W. Shoppee
DOI:10.1039/jr9550001365
日期:——
Shoppee et al., Journal of the Chemical Society, 1956, p. 2492,2497
作者:Shoppee et al.
DOI:——
日期:——
Pace Length Effects in Human Walking: “Groucho” Gaits Revisited
作者:John E. A. Bertram、Paul D'antonio、Jaime Pardo、David V. Lee
DOI:10.1080/00222890209601949
日期:2002.9
In the present study, the authors explored the effect of manipulating the distance between footfalls (pace length) in level walking in 3 men. The translational kinetic energy to gravitational potential energy (E-k-E-p) exchange was found to be maintained until pace length reached approximately 110% of single limb length. Beyond that pace length, the compliance of the support limb increased, apparently to allow the muscular absorption of excess kinetic energy. E-p oscillations decreased with increasing limb compliance, and the participants could control that relationship with pace length alone. The authors compared the present results with previous descriptions of the relationship between limb compliance and pace length in running. An analog of the running relationship holds for walking as well. The trigger for those gait modifications has not yet been identified, however. The present results have implications for the exploration of the integrated control of mechanical consequences in human locomotion and for understanding the walk-run transition in bipeds other than humans, such as ground-dwelling birds.