Iron-Catalyzed 1,4-Hydroboration of 1,3-Dienes

Wu, Jiacheng; Moreau, Benoît; Ritter, Tobias

doi:10.1021/ja9048493

Cited by 277 publications

(135 citation statements)

References 42 publications

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confidence: 99%

“…[8] Conjugated dienes and especially 1,3-dienes,asacommon feedstock, are ideal nucleophilic allyl metal precursors [9] and readily participate in allylic transformations of carbonyls and imines. [10] We envisioned merging the borylcupration of ac onjugated diene [11] (Scheme 1, step A) and enantioselective imine allyl ation (Scheme 1, step B) in the presence of as uitable chiral copper catalyst.…”

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Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

et al. 2016

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AC u-catalyzed diastereo-and enantioselective borylative coupling reaction of 1,3-dienes with imines was realized. Branched homoallylic amines are readily prepared in as yn-selective manner with high regio-, diastereo-and enantioselectivity.M oreover,t hese three-component coupling reactions feature good functional-group compatibility and easy access to the substrates and catalyst.Asymmetric allylation reactions [1] of imines have received increasing interests from the synthesis community [2] because enantioenriched homoallylic amine products are useful building blocks in organic synthesis and medicinal chemistry.[3] Copper catalysis is an efficient approach to promote the enantioselective addition of terminal allyl transmetalation reagents (e.g., with B, Si, and Sn) to imines, [4] however,C ucatalyzed asymmetric, nucleophilic addition to imines with functionalized (e.g., g-substituted) allyl metal reagents remain challenging.T his is probably due to inefficiencyo f the transmetalation event arising from increased steric hindrance,t he weak electrophilicity/reactivity of imines, and/or difficulties in predicting the regio-and stereochemical outcome of additions.N ew and efficient approaches to generating and utilizing functionalized allyl metal reagents in the presence of acopper catalyst hold promise for accessing complex homoallylic amines,a nd these methods will expand the application of catalytic asymmetric allylation chemistry.Since the seminal work of borylcopper catalysis reported by the Ito [5] and the Miyaura [6] groups,C u-catalyzed borylative coupling reactions have been recognized as an important method for generating boron-containing organocopper species in situ from an unsaturated hydrocarbon. [7] In this context, Hoveyda pioneered the use of boron-functional allylcopper intermediates in enantioselective allylation of aldehydes/ketones, [7f] allyllic esters, [7i] and enoates.[7k] However,Cu-catalyzed borylative coupling of unsaturated hydrocarbon substrates and imines is less developed.[8] Conjugated dienes and especially 1,3-dienes,asacommon feedstock, are ideal nucleophilic allyl metal precursors [9] and readily participate in allylic transformations of carbonyls and imines.[10] We envisioned merging the borylcupration of ac onjugated diene [11] (Scheme 1, step A) and enantioselective imine allyl ation (Scheme 1, step B) in the presence of as uitable chiral copper catalyst. This approach could afford useful homoallylic amines containing an easily derivatizable boron motif.In this method, possible complications include the undesired borylation of imines, [12] poisoning of the metal catalyst by imines or products,a nd difficulty in controlling the regio-(linear vs.b ranched products) [7k,11a] and stereoselectivity (enantio-and/or diastereoselectivity).To test the feasibility of our proposed transformation, we chose acomplex of CuCl and chiral sulfoxide-phophine (SOP, L1)[7j] as acatalyst in preliminary experiments.Inthe presence of isoprene (5 equiv), 1.5 equiv of B 2 (pin) 2 ,a nd NaO...

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Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

et al. 2016

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“…[9] Recently, Ritter et al presented an iminopyridine iron catalyst for selective 1,4-hydroboration of 1,3-dienes. [10] However, to date the hydroboration of widely available and commercially relevant alkenes using iron catalyst has remained unknown. Herein, we report the synthesis of an electron-rich iron pincer complex and its application to the first example of iron-catalyzed alkene hydroborations.…”

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“…The Ritter complex (iminopyridine)-FeCl 2 3 acts as a catalyst precursor for 1,3-diene hydroboration. [10] However, complex 3 (5 mol %), upon addition of NaBHEt 3 (15 mol %), did not effect a-olefin hydroboration (entry 1). [11] The reaction using FeCl 2 alone (5 mol %) or a combination of FeCl 2 /2,2'-bipyridine (5 mol % each) in the presence of NaBHEt 3 also gave no hydroboration product (entries 2 and 3).…”

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Iron‐Catalyzed, Atom‐Economical, Chemo‐ and Regioselective Alkene Hydroboration with Pinacolborane

et al. 2013

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“…[104] Reduction of iron(II) iminopyridine complex 207/208 using activated magnesium gave an active catalyst for the addition of pinacol borane to 1,3-dienes (Scheme 43). It was proposed that an iron(0) catalyst was formed in situ, which may be stabilised by the redox activity of the iminopyridine ligand.…”

Section: Hydroborationmentioning

confidence: 99%

Iron‐Catalysed Hydrofunctionalisation of Alkenes and Alkynes

2014

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The metal‐catalysed hydrofunctionalisation of alkenes and alkynes provides a convenient and atom‐economic route to diversely functionalised products with control of regio‐, chemo‐ and stereoselectivity. As one of the most abundant elements on earth, iron offers a level of sustainable and long‐term availability that is uncommon for most transition metals. Although iron is commonly found in the oxidation states of +2 and +3, the use of redox‐active ligands has allowed the synthesis and application of low oxidation state iron complexes in catalysis. A broad range of hydrofunctionalisation reactions have been developed by using iron catalysts in a wide variety of oxidation states. Intense development over the past decade has resulted in the development of iron‐catalysed hydroamination, hydroalkoxylation, hydrocarboxylation, hydrothiolation, hydrovinylation, hydrosilylation, hydroboration, hydrophosphination, hydromagnesiation and carbonylation reactions, amongst others. With the field still in its infancy, there is great potential for further developments in the mechanistic understanding and synthetic and industrial applicability of these processes.

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Iron-Catalyzed 1,4-Hydroboration of 1,3-Dienes

Cited by 277 publications

References 42 publications

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

Iron‐Catalyzed, Atom‐Economical, Chemo‐ and Regioselective Alkene Hydroboration with Pinacolborane

Iron‐Catalysed Hydrofunctionalisation of Alkenes and Alkynes

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