Resolution of CpMo(NO)X(.eta.3-2-methallyl) complexes and their enantioselective reactions with an aldehyde

Faller, J. W.; Nguyen, Jenna Thu; Ellis, W. Chadwick; Mazzieri, María R.

doi:10.1021/om00028a070

Cited by 54 publications

(37 citation statements)

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“…Conceptually, more efficient 'chirality transfer' should be feasible when the metal itself is a stereogenic centre. 2 These so-called chiral-at-metal complexes are finding increasing use in catalytic asymmetric processes 3 and in materials applications (e.g. chiroptical switches, non-linear optics) 4 as the drive to understand the effects of metal-based asymmetry continues.…”

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confidence: 99%

Monovalent chiral-at-copper complexes: halide-controlled diastereoselectivity

2012

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Monovalent chiral-at-copper complexes: halide-controlled diastereoselectivity

2012

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“…the faster the rate the better the ee. 3 The rates for the reactions of the halides decrease in the order 2 > 3 > 4 and the ee of the products follow the same trend. The camphorsulfonate complex gives the highest de and it also has the fastest reaction.…”

Section: Reactions With Enantiomerically Pure Aldehydesmentioning

confidence: 82%

Reagent control of stereochemistry in allylic additions to chiral aldehydes with CpMo(NO)(X)(2‐methallyl) complexes of high enantiomeric purity

Faller

Nguyen

Mazzieri

1995

Applied Organom Chemis

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“…[Mo(CO)3(MeCN)3] by chiral allylic substrate 64, which is reported to proceed with retention to yield allylmolybdenum complex 66a [144] via chelating olefinic intermediate 65a (Scheme 23a). [153,154] Lower selectivity is observed under different conditions; the pathway in Scheme 23b is competitive when there is a high concentration of the molybdenum precatalyst species ML6 present, [153] but πolefin species are implicit in both routes. Scheme 23 also pictures the two generalised transition states TS1 and TS2 that are applicable to a concerted mechanism with retention, and an intramolecular SN2type mechanism with inversion, respectively.…”

Section: Mechanistic Features Structural Aspects and Dynamic Behaviourmentioning

confidence: 99%

“…The transition states TS1 and TS2 are general for oxidative additions to allyl-X that may proceed with retention or inversion, respectively. [153,154] The alternative mechanism proposed by Brisdon et al [132] involves a direct SN2 expulsion of the allylic leaving group Xʹ by 56 to yield 7-coordinate σ-allyl intermediate 67 (Scheme 24), followed by dissociation of CO to furnish η 3 -allyl complex 53. It is not clear whether SN2 (TS3) or SN2ʹ (TS4) mechanisms are applicable in this case; whereas SN2ʹ reactions are less common, it has been alluded to in allylic substitutions involving rhodium(III) complexes [RhCl(PPh)3(η 3 -allyl)X] on account of increased substitution of the alkene significantly increasing reaction times.…”

Section: Scheme 22mentioning

confidence: 99%

η3-Allyl carbonyl complexes of group 6 metals: Structural aspects, isomerism, dynamic behaviour and reactivity

Ryan

Cardin

Hartl

2017

Coordination Chemistry Reviews

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Contents 1. Introduction 2. Complexes [CpM(CO)2(η 3 -allyl)] and related compounds 2.1. Synthetic strategies 2.2. Exo ⇌ endo isomerism 2.3. 95 Mo and 183 W NMR spectroscopy 2.4. Oxidized cationic complexes -reactivity, fluxionality, structural features 2.5. Mixed nitrosyl carbonyl complexes [CpM(CO)(NO)(η 3 -allyl)] + (M = Mo, W) 3. Complexes [M(CO)2(η 3 -allyl)(α-diimine)X] (X = anionic monodentate ligand) and related compounds 3.1. Synthetic strategies 3.2. Mechanistic features, structural aspects, and dynamic behaviour 3.3. Monodentate ligands bound to M(CO)2(η 3 -allyl)(L⏜L): reactivity and intermediacy in allylic alkylations 3.4. Redox Properties and Electrocatalysis 4. Amidinato and pyrazolato complexes related to [M(CO)2(η 3 -allyl)(α-diimine)X] 4.1. Synthesis and dynamic behaviour 4.2. Coordinatively unsaturated species and their reactivity 5. Summary and outlook Acknowledgement References 2 ABSTRACTTransition metal complexes with π-allylic ligands remain an attractive topic in organometallic chemistry, given the numerous reports of a wide variety of synthetic routes, dynamic behaviour and reactivity, structural (including isomerism), spectroscopic and redox properties, and applications in organic synthesis and catalysis. Surprisingly, despite the considerable interest in the rich and varied chemistry of this family of organometallic compounds, there is no recent review. This review is focused on π-allylic representatives of low-cost Group-6 metals bearing one or more carbonyl ligand, the coordination sphere being complemented with η 5cyclopentadienyl (Section 2), chelating ligands, including redox active α-diimines and various complementary diphosphine (Section 3) and novel anionic amidinate or pyrazolate (Section 4) ligands. In Section 1 particular attention is paid to rearrangements of the π-allylic ligand, namely exo and endo isomerism, interconversion mechanisms, fluxionality, and agostic interactions. In addition, the application of multinuclear NMR spectroscopy to the elucidation of such isomerism, and the effect of the metal centre oxidation state on the bonding, dynamic behaviour and reactivity of the π-allylic ligand are described. The detailed mechanistic description of the synthetic routes and dynamic behaviour of selected representatives of αdiimine complexes in Section 2 is followed by a description of the [M(CO)2(η 3 -allyl-H,R)(αdiimine)] 0/+ fragment as a convenient scaffold for diverse monodentate ligands participating in a range of substitution, insertion, intramolecular migration and C-C coupling reactionsfrequently involving also the π-allylic ligand, such as allylic alkylation. Special attention is devoted to selected examples of redox and acid-base reactivity of the α-diimine complexes with emphasis on prospects in electrocatalysis. The amidinate (and related pyrazolate) ligands treated in Section 4 may directly replace the π-allylic ligand in some cyclopentadienyl complexes (Section 2) or the α-diimine ligand in some dicarbonyl π-allylic complexes (Section 3). The brief description...

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Resolution of CpMo(NO)X(.eta.3-2-methallyl) complexes and their enantioselective reactions with an aldehyde

Cited by 54 publications

References 0 publications

Monovalent chiral-at-copper complexes: halide-controlled diastereoselectivity

Monovalent chiral-at-copper complexes: halide-controlled diastereoselectivity

Reagent control of stereochemistry in allylic additions to chiral aldehydes with CpMo(NO)(X)(2‐methallyl) complexes of high enantiomeric purity

η3-Allyl carbonyl complexes of group 6 metals: Structural aspects, isomerism, dynamic behaviour and reactivity

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