Ketyl−Allene Cyclizations Promoted by Samarium(II) Iodide
作者:Gary A. Molander、Elizabeth Pollina Cormier
DOI:10.1021/jo047887s
日期:2005.4.1
Samarium(II) iodide has proven to be an effective reagent for intramolecular reductive coupling reactions. Previous investigations of intramolecular ketyl−olefin coupling reactions provided carbocycles in excellent yield and good diastereoselectivity. This method has been extended to ketyl cyclizations with allenes. Substrates leading to both carbocycles and heterocycles in a selective manner are explored
Cu-Catalyzed C–H Allylation of Benzimidazoles with Allenes
作者:Yaxi Dong、Bernhard Breit
DOI:10.1021/acs.orglett.1c02346
日期:2021.9.3
CuH-catalyzed intramolecular cyclization and intermolecular allylation of benzimidazoles with allenes have been described. The reaction proceeded smoothly with the catalytic system of Cu(OAc)2/Xantphos and catalytic amount of (MeO)2MeSiH. This protocol features mild reaction conditions and a good tolerance of substrates bearing electron-withdrawing, electron-donating, or electron-neutral groups. A
Use of Group 4 Bis(sulfonamido) Complexes in the Intramolecular Hydroamination of Alkynes and Allenes
作者:Lutz Ackermann、Robert G. Bergman、Rebecca N. Loy
DOI:10.1021/ja0361547
日期:2003.10.1
the intramolecularhydroamination of alkynes and allenes more efficiently than Cp-based species. We report here that electron-withdrawing and sterically demanding bis(sulfonamido) ligands lead to enhanced catalytic activity. Zirconium analogues have also been prepared, and the tosyl-substituted complex 20 has been structurally characterized. As in the titanium series, bis(sulfonamido) zirconium catalysts
heteroatomic group (hydroxy, alcoxy, halogen, dialkylamino) or a phenyl in the γ position exhibits a strong peak corresponding to the loss of C2H4 (28a.m.u.) from the molecular ion. This is commonly the base peak of the spectra and due to a McLafferty type transfer of the heteroatom or phenyl group to the central allenic carbonatom. The methylgroup shows a lower migratory aptitude in such a process. This
被在γ位上带有杂原子基团(羟基,烷氧基,卤素,二烷基氨基)或苯基的烃链取代的烯丙基化合物的质谱表现出与C 2 H 4损失相对应的强峰(28a.mu)来自分子离子。这通常是光谱的基峰,这是由于杂原子或苯基基团向中心烯丙碳原子的麦克拉费蒂型转移。在这种过程中,甲基显示出较低的迁移能力。在γ-卤素和γ-羟基酮,烯烃,炔烃或芳烃的光谱中未观察到涉及杂原子基团迁移的这种类型的断裂,并且似乎是烯丙基键的特征。提出了杂原子基团(或苯基)对中心烯丙基碳原子的亲核攻击。
Rhodium‐Catalyzed Asymmetric Allylation of Malononitriles as Masked Acyl Cyanide with Allenes: Efficient Access to β,γ‐Unsaturated Carbonyls
作者:Christian P. Grugel、Bernhard Breit
DOI:10.1002/chem.201804150
日期:2018.10.12
A rhodium‐catalyzed regio‐ and enantioselective intermolecular allylation of malononitriles as masked acyl cyanides (MAC) with terminal and symmetrical internal allenes is reported. A RhI/Josiphos catalytic system combined with subsequent oxidative degradation of the primary adducts enables a straightforward access to α‐branched, β,γ‐unsaturated carbonyl compounds. The present protocol exhibits perfect
报道了铑催化的丙二腈的区域和对映选择性分子间烯丙基化反应,即带有末端和对称内部烯基的掩蔽酰基氰化物(MAC)。Rh I / Josiphos催化体系与随后的一级加合物的氧化降解相结合,可以直接获得α支化,β,γ-不饱和羰基化合物。本方案在烯丙基化步骤中展现出完美的原子经济性,并且具有良好的官能团相容性。此外,使用α-取代的丙二腈可以构建全碳四元中心。