Oligomerization and Hydroamination of Terminal Alkynes Promoted by the Cationic Organoactinide Compound [(Et2N)3U][BPh4]

Recent advances in organothorium and organouranium catalysis

“…44 NMR spectra has indicated that complexes of the type [(R 2 N) 3 U][BPh 4 ] normally adopt a zwitterionic structure in non-coordinating solvents, with two phenyl groups of BPh 4 coordinated to the metal center. 45 Similar reaction of [(Et 2 N) 3 U][BPh 4 ] with tert-butylamine allowed the formation of complex [( t BuNH 2 ) 3 ( t BuNH) 3 U]-[BPh 4 ] (eqn ( 8)). 46 The X-ray diffraction of the product Scheme 1 Alternative synthetic pathways for the preparation of highvalent organouranium imido complexes and their reactivity with hydrogen.…”

“…The U-N(amido) bond lengths average 2.20(2) A ˚were similar to those determined in the distorted facial octahedral cation [(Et 2 N) 3 (THF) 3 U] + (mean value of 2.18(1) A ˚). 45 The complex [( t BuNH 2 ) 3 ( t BuNH) 3 U]-[BPh 4 ] is a unique uranium(IV) complex with primary amine ligands that were crystallographically characterized. 47 The mean U-N(amino) bond distance of 2.67(3) A ˚can be compared with the average U-N bond length of 2.79(2) A ˚in UCl 4 (Me 2 NCH 2 CH 2 NMe 2 ) 2 .…”

Aquapalladium Complex: A Stable and Convenient Catalyst for the Intermolecular Hydroamination of Alkynes

“…As a result of the great research efforts in this area, it is now feasible to carry out the intermolecular hydroamination of unactivated alkynes in the presence of different kinds of metal catalysts 2−4. However, a major drawback of some catalysts lies in their air and/or light sensitivity, which demands they be handled with great care,2e,2f,3 and in addition they can only be used for the hydroamination of terminal alkynes 2a−2d. Recently, we reported that the intermolecular hydroamination of alkynes proceeds smoothly with o ‐aminophenols in the presence of a palladium catalyst that is easily handled without special care 5.…”

Catalytic Organic Transformations Mediated by Actinide Complexes

“…The coupling of terminal alkynes to give oligomeric products through actinide mediated C-H activation processes has been extensively investigated by Eisen and co-workers, using the organoactinides Cp*2AnMe2 (5 and 6) [53,54,64], as well as the cationic uranium amide [(Et2N)3U] [BPh4] (11) [65][66][67] as pre-catalysts. While the chemo-and regio-selectivity of the oligomerization process depends on the steric encumbrance of the R substituent on the alkyne RCCH, leading to a different regioselectivity for bulky and non-bulky alkynes, the uranium complex 5 and the isostructural thorium compound 6 displays a similar reactivity [53,64].…”

“…R = Alkyl, Aryl, or SiMe3. The regioselectivity of the alkyne insertion into the Th-C bond is explained in Figure 5 In addition to the organoactinides 5 and 6, the cationic uranium complex [(Et2N)3U] [BPh4] (11) was successfully applied in the oligomerization and cross oligomerization of terminal alkynes, leading to the spectroscopic characterization of the first π-alkyne uranium complex as the key intermediate in the catalytic cycle [65][66][67]. Recently, Meyer et al, investigated the reactivity of a uranium (III) coordination complex toward various terminal acetylenes, which led to the formation of binuclear uranium (IV) species that could be isolated and structurally characterized [68].…”