Detail of "54678-23-8"

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Further insight into lower-order cuprate chemistry: on the use of CuBr×Me2S versus CuI en route to R2CuLi

Further insight into lower-order cuprate chemistry: on the use of CuBr×Me2S versus CuI en route to R2CuLi. Lipshutz, Bruce H.; Whitney, Scott; Kozlowski, Joseph A.; Breneman, Curt M. (Dep. Chem., Univ. California, Santa Barbara, CA 93106, USA).Several reagents with their cas registry numbers 54678-23-8 and 557-35-7 are used here. Tetrahedron Lett., 27(36), 4273-6 (English) 1986. CODEN: TELEAY. ISSN: 0040-4039. DOCUMENT TYPE: Journal CA Section: 21 (General Organic Chemistry) Section cross-reference(s): 23, 29 Both 1H and 7Li NMR expts. show that 2MeLi + either CuBr×Me2S or CuI in THF afford the same species, Me2CuLi (+ LiX). However, use of the former source of Cu(I), depending upon its purity and esp. handling, can lead to significantly decreased chem. yields. The reasons behind these observations and the implications for cuprate couplings are discussed. .

Mechanism of copper(I)-catalyzed cyclopropanation: a DFT study calibrated with copper(I) alkene complexes

Mechanism of copper(I)-catalyzed cyclopropanation: a DFT study calibrated with copper(I) alkene complexes. Straub, Bernd F.; Gruber, Irene; Rominger, Frank; Hofmann, Peter ( Organisch-Chemisches Institut der Universitaet Heidelberg, Heidelberg D-69120, Germany). Journal of Organometallic Chemistry, 684(1-2), 124-143 (English) 2003 Elsevier Science B.Chemicals with cas numbers 649761-69-3 and 54678-23-8 also play role.V. CODEN: JORCAI. ISSN: 0022-328X. DOCUMENT TYPE: Journal CA Section: 29 (Organometallic and Organometalloidal Compounds) Section cross-reference(s): 75 The complete catalytic cycle of copper-catalyzed cyclopropanation is investigated by d. functional model calcns. The study focuses on obtaining accurate relative stabilities of the ligand-metal cores of all catalytic intermediates and transition states. The copper iminophosphanamide [H2P(NH2)2-k2N]Cu serves as model fragment, since three copper catalyst key intermediates with an iminophosphanamide ligand have been isolated or detected. The electronic structure of the active intermediates, copper(I) carbenes of the d10-ML3 type, and their reactivity towards ethene and vinyl alc. is investigated. The reliability of the computed data is confirmed by their comparison with exptl. data of [t-Bu2P(NSiMe3)2-k2N]Cu alkene and alkyne complexes, using relative ligand binding strengths and alkene ligand rotation barriers. The uncharged nature of the model complexes minimizes solvation artifacts and thus renders the evaluation of associative and dissociative ligand exchange pathways possible. The associative alkene ligand exchange with diazoalkane to a kN,kO-diazoalkane complex, subsequent intramol. rearrangement to a kC-complex and N2 extrusion are identified on the most probable pathway to the electrophilic copper(I) carbene complexes of the Fischer type. They are predicted to react with alkenes to labile cupracyclobutanes with a planar N2CuIIIC2 core, which undergo facile reductive elimination of a cyclopropane deriv. .