通过将羰基官能团转化为烯醇九氟甲磺酸酯中间体,然后消除以得到 CC 三键,从羰基化合物中以良好至极好的分离产率获得了末端和内部乙炔。磷腈碱与温和亲电子的九氟丁烷-1-磺酰氟相结合均匀地诱导了一锅法转化。该方法是迄今为止报道的方法中最通用的,因为它适用于无环酮和醛。只有适度的动力学区域选择性有利于从甲基正烷基酮实现的 alk-1-yne 代表了该方法的局限性。在所有其他情况下,都获得了单独的炔烃产品。
The chemistry of η5-CpCo(CO)(maleoyl) and η5-CpCo(CO)(phthaloyl) complexes
作者:Lanny S. Liebeskind、Charles F. Jewell
DOI:10.1016/0022-328x(85)87376-9
日期:1985.4
Insertion of η5-CpCo(CO)2 into dimethylcyclobutenedione and benzocyclobutenedione gave high yields of η5-CpCo(CO)(dimethylmaleoyl) and η5-CpCo(CO)(phthaloyl); respectively. Replacement of the carbonmonoxide ligand in these complexes with thermally labile ligands (CH3CN, PhCN, C5H5N, (C2H5)2S) allowed a facile reaction with alkynes to occur. The maleoyl cobalt complex gave very high yields of stable
的η插入5 -CpCo(CO)2成dimethylcyclobutenedione和benzocyclobutenedione给出的η高收率5 -CpCo(CO)(dimethylmaleoyl)和η 5 -CpCo(CO)(邻苯二甲酰基); 分别。用热不稳定的配体(CH 3 CN,PhCN,C 5 H 5 N,(C 2 H 5)2 S)取代这些配合物中的一氧化碳配体可以轻松地与炔烃反应。所述马来酰钴络合物,得到稳定的非常高的产率η 5,其裂解以游离醌治疗用铈(IV)-CpCo(醌)络合物。邻苯二甲酰钴络合物反应形成不稳定的η5- CpCo(萘醌)配合物和游离萘醌。
.sigma.-Bond metathesis for carbon-hydrogen bonds of hydrocarbons and Sc-R (R = H, alkyl, aryl) bonds of permethylscandocene derivatives. Evidence for noninvolvement of the .pi. system in electrophilic activation of aromatic and vinylic C-H bonds
作者:Mark E. Thompson、Steven M. Baxter、A. Ray Bulls、Barbara J. Burger、Michael C. Nolan、Bernard D. Santarsiero、William P. Schaefer、John E. Bercaw
DOI:10.1021/ja00235a031
日期:1987.1
H/sub 2/ and hydrocarbons. Experiments designed to probe the mechanism of these processes have been carried out, and the possibility of involvement of the ..pi.. system in electrophilic activation of aromatic and vinylic C-H bonds has been examined. A picture of the transition state for such sigma-bond metathesis reactions is developed, which accounts for the relative reactivities of sp-, sp/sup 2/-
Sickle cell disease affects 70,000 Americans who experience an average of 0.8 painful episodes each year. The pathophysiology of sickle cell pain is not completely understood. The disease is characterized by both acute and chronic pain syndromes. Patients with sickle cell pain often encounter barriers to receiving appropriate care, including lack of continuity of care and perceived opiate addiction. Studies describing pharmacotherapy for sickle cell pain have been primarily retrospective and uncontrolled. In analyzing the available literature regarding pathophysiology, assessment, and treatment of sickle cell pain, we found a need for increased practitioner education and intervention to improve the level of care provided to patients with this disease.
Diverse catalytic activity of the cationic actinide complex [(Et2N)3U][BPh4] in the dimerization and hydrosilylation of terminal alkynes. Characterization of the first f-element alkyne π-complex [(Et2N)2U(CCtBu)(η2-HCCtBu)][BPh4]
作者:Aswini K. Dash、Jia Xi Wang、Jean Claude Berthet、Michel Ephritikhine、Moris S. Eisen
DOI:10.1016/s0022-328x(00)00207-2
日期:2000.6
double hydrosilylated alkene, in which the two silicon moieties are connected at the same carbon atom, is obtained. The catalytic hydrosilylation of (TMS)CCH and PhSiH3 with [(Et2N)3U][BPh4] was found to proceed only at higher temperatures. Mechanistically, the key intermediate seems to be the uranium–hydride complex [(Et2N)2UH][BPh4], as evidenced by the lack of the dehydrogenative coupling of silanes