Studies in the Terpene Series. XIV.1 Skeletal Isomerization and Hydrogen Transfer of Cyclic Olefins in the Presence of Alumina—Hydrogen Chloride and Silica—Alumina Catalysts2
Efficient transfer-dehydrogenation of alkanes catalyzed by rhodium trimethylphosphine complexes under dihydrogen atmosphere
作者:John A. Maguire、Angelo Petrillo、Alan S. Goldman
DOI:10.1021/ja00050a030
日期:1992.11
RhL 2 Cl(CO) (1; L=PMe 3 ), a known catalyst for the photodehydrogenation of alkanes, is found to catalyze thehighly efficientthermal (nonphotochemical) transfer-dehydrogenation of alkanesunderhigh-pressurehydrogenatmosphere. The proposed mechanism involves addition of H 2 , loss of CO, and transfer of H 1 to a sacrificial acccptor, thereby generating RhL 2 Cl, the same catalytically active fragment
RhL 2 Cl(CO) (1; L=PMe 3 ) 是一种已知的烷烃光脱氢催化剂,被发现在高压氢气气氛下催化烷烃的高效热(非光化学)转移脱氢。所提出的机制涉及 H 2 的添加、CO 的损失以及 H 1 向牺牲受体的转移,从而产生 RhL 2 Cl,这是由 1 的光解形成的相同催化活性片段。
The Interaction of π Orbitals with a Carbocation over Three σ Bonds
作者:Joseph B. Lambert、Sol M. Ciro
DOI:10.1021/jo951643d
日期:1996.1.1
The semi-pi analogue of double hyperconjugation (''hyperconjugation/conjugation'') has been examined in 4-isopropylidenecyclohexyl mesylate (4-OMs) by comparison with the saturated analogue, trans-4-isopropylcyclohexyl mesylate(5-OMs). The unsaturated substrate reacts in 97% trifluoroethanol only four times faster than the saturated substrate. Raber-Harris plots indicate that both substrates react by k(s) mechanisms; i.e., solvolysis occurs with solvent assistance rather than carbocation formation. These results are consistent with the absence of a direct, through-bond interaction of the double bond with the reactive center. The absence is caused at least in part by less than ideal overlap of the gamma, delta pi orbitals with the alpha,beta sigma orbitals. In contrast, an electron-rich tin atom attached to the 4-position provides a large rate enhancement and changes the mechanism to carbocation formation through double hyperconjugation.
A new reducing system: calcium metal in amines. Reduction of aromatic hydrocarbons
作者:Robert A. Benkeser、Frank G. Belmonte、Jahyo Kang
DOI:10.1021/jo00165a003
日期:1983.8
BENKESER, R. A.;BELMONTE, F. G.;KANG, JAHYO, J. ORG. CHEM., 1983, 48, N 17, 2796-2802