Structural Studies of (rac)-BIPHEN Organomagnesiates and Intermediates in the Halogen–Metal Exchange of 2-Bromopyridine

Abstract

This version is available at https://strathprints.strath.ac.uk/54032/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Pe 2 4 have been prepared by complexation of the appropriate dialkylmagnesium compound with in-situ prepared Li(rac-BIPHEN) in a mixture of hydrocarbon/THF. For all structures, the Mg centers are four-coordinate (and retain the alkyl groups); however, in 2 and 3 the two Li centers have different coordination spheres (one binding to one THF molecule, the other to two). The solid-state structures of 2 and 3 are essentially isostructural with that of 4 except that both Li atoms in this molecule have equivalent coordination spheres. The solution behaviors of these three molecules have been studied by 1 H, 13 C and DOSY NMR spectroscopy. During the synthesis of 2, it was discovered that a (rac)-BIPHEN-rich (or n-butyl-free) lithium magnesiate (THF) 4 Li 2 Mg{(rac)-BIPHEN)}fo 2 2b could be isolated. The lithium precursor to 2-5, (THF) 4 .Li 4 {(rac)-BIPHEN)} 2 1 has also been isolated. Within the molecular structure of this tetranuclear complex, there are three different Li coordination environments. Finally, 2 has already shown promise as a reagent in a halogen-metal exchange reaction with 2-bromopyridine. The structural chemistry at play in this reaction was probed by X-ray crystallography and NMR spectroscopy. The organometallic intermediate pyridyl-magnesiated 5 (THF) 2 .Li 2 Mg{(rac)-BIPHEN)}(2-pyridyl) 2 was isolated in high yield. Structural Studies of (rac)-BIPHEN Organomagnesiates and

Reaching Milestones in the Oxygenation Chemistry of Magnesium Alkyls: towards Intimate States of O2 Activation and the First Monomeric Well‐Defined Magnesium Alkylperoxide

“…Synthesis and characterization of neo‐pentylmagnesium complexes incorporating a β ‐diketiminate ligand : In the reported studies on the oxygenation magnesium alkyls supported by a β ‐diketiminate ligand, we replaced the Mg‐bond alkyl substituent from benzyl to neo‐pentyl. We note that the chemistry of neo‐pentylmagnesium derivatives is rather scare, and to the best of our knowledge, there is only a handful of examples of structurally characterized neo‐pentylmagnesium complexes . The neo‐pentylmagnesium complex, [( dipp BDI)MgCH 2 CMe 3 ] ( 1 ), and its solvated form [ dipp BDIMgCH 2 CMe 3 (thf)] ( 2 ) were quantitatively prepared in equimolar reaction of (Me 3 CCH 2 ) 2 Mg and the dipp BDI‐H proligand in toluene or thf, respectively ( dipp BDI=deprotonated 2‐[(2,6‐diisopropylphenyl)amino]‐4‐[(2,6‐diisopropylphenyl)imino]pent‐2‐ene).…”

“…We note that the chemistry of neo-pentylmagnesiumd erivatives is rather scare,a nd to the best of our knowledge,t here is only a handfulo fe xamples of structurally characterized neo-pentylmagnesiumc omplexes. [61][62][63][64] The neo-pentylmagnesium complex, [( dipp BDI)MgCH 2 CMe 3 ]( 1), and its solvated form [ dipp BDIMgCH 2 CMe 3 (thf)] (2)w ere quantitatively prepared in equimolar reaction of (Me 3 CCH 2 ) 2 Mg and the dipp BDI-H proligand in tolueneo rt hf, respectively ( dipp BDI = deprotonated 2-…”

Transition-Metal-Free Enantioselective Reactions of Organo­magnesium Reagents Mediated by Chiral Ligands

“…26 The structures of both the chiral di-nbutylmagnesiate 2b and the corresponding magnesiated pyridyl-containing intermediate 3 were established by Xray crystallography and NMR spectroscopy. 27 Addition of aromatic aldehydes to the pyridyl magnesiate 3 led to a range of chiral pyridyl carbinols 1, which are valuable precursors of bioactive molecules and chiral ligands for asymmetric synthesis. 28 A very low temperature (-100 °C) is crucial to obtain acceptable enantioselectivities (up to 76% ee), but is, however, seriously deleterious for the conversion (up to 53%).…”

Organomagnesiate‐Promoted Enantioselective Cascade Process: Straightforward Access to Chiral 3‐Substituted Isobenzofuranones

“…This was made possible by the ability of the central magnesium to easily accommodate chiral ligands such as ( R,R )‐TADDOL or ( R )‐BIPHEN H2. The X‐Ray and NMR characterization of the BIPHEN‐based magnesiate and resulting azinylorganometallic intermediate revealed a perfectly controlled arrangement of the ligands around the central metal as a single compound, and therefore not as an aggregate, allowing for a high level of enantiocontrol along the reaction of azinylmagnesiates with aldehydes.…”