Identification of Suitable Ligands for a Transition Metal-Catalyzed Reaction: Screening of a Modular Ligand Library in the Enantioselective Hydroboration of Styrene

Blume, Florian; Zemolka, Saskia; Fey, Thorsten; Kranich, Remo; Schmalz, Hans‐Günther

doi:10.1002/1615-4169(200209)344:8<868::aid-adsc868>3.0.co;2-m

Cited by 95 publications

(34 citation statements)

References 5 publications

(12 reference statements)

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“…2.1 [37][38][39][40][41]. A majority of the experiments employ styrene or a simple derivative as the reactant, and for good reasons.…”

Section: Diphosphine Ligandsmentioning

confidence: 91%

Rhodium‐Catalyzed Hydroborations and Related Reactions

Brown¹

2005

Modern Rhodium‐Catalyzed Organic Reactions

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The development of metal-catalyzed hydroboration was initiated in a single paper by Männig and Nöth in 1985 [1]. They demonstrated that catecholborane reacted with simple alkenes in the presence of transition-metal catalysts, the most effective being Wilkinson's catalyst, RhCl(PPh 3 ) 3 . Since this reaction of catecholborane with alkenes is normally rather slow, even at elevated temperatures, this observation provided a real opportunity for catalysis. Prior to this work, the only precedent had been the addition of a secondary alkoxyborane to the same rhodium complex, giving a borylrhodium hydride analogous to known silylrhodium hydrides [2]. The synthetic potential of catalytic hydroboration was quickly realized and further extended through Burgess's demonstration of asymmetric catalysis [3], which was later refined and extended by Hayashi [4]. All this early work has been reported in a 1991 review [5], with a later and more extensive review by Belet'skaya and Pelter in 1997 [6]. As these reviews are readily available, the present chapter is confined largely to developments that have taken place since the beginning of 1997. Fig. 2.1 summarizes some of these early milestones. Although metal catalysts other than rhodium have been examined, for example in the palladiumcatalyzed hydroboration of allenes [7], the majority of the interesting developments have been made with rhodium.In the interim period, results have accumulated steadily, in endeavors to address and extend the chemistry beyond the initial perceived limitations. These limitations include the following: (a) the effective catalytic syntheses are confined to the reactions utilizing catecholborane; (b) the scope of alkenes for which efficient rate, regio-and enantioselectivity can be achieved is limited, and (c) the "standard" transformation mandates the oxidation of the initially formed (secondary) boronate ester to a secondary alcohol, albeit with complete retention of configuration [8]. Nonetheless, for noncatalytic hydroboration reactions that lead to the formation of a trialkylborane, a wide range of stereospecific transformations may be carried out directly from the initial product, and thereby facilitate direct C-N and C-C bond formation [9].A reaction pathway for catalytic hydroboration was suggested by Evans and co-workers [10], and amplified through computational studies [11]. This involves the rhodium acting through oxidative addition across the B-H bond, and the resulting borylrhodium hydride complexing to the alkene (reversibly). This is followed by a hydride migration, with a subsequent reductive elimination of the alkylboronate ester to complete 33 2

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“…2.1 [37][38][39][40][41]. A majority of the experiments employ styrene or a simple derivative as the reactant, and for good reasons.…”

Section: Diphosphine Ligandsmentioning

confidence: 91%

Rhodium‐Catalyzed Hydroborations and Related Reactions

Brown¹

2005

Modern Rhodium‐Catalyzed Organic Reactions

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“…For example, Schmalz and co-workers reported the synthesis of a library of chiral bidentate phosphorus ligands according to a modular strategy, including ligands based on the TAD-DOL framework. 41,42 Some of these ligands were tested in the asymmetric rhodium-catalyzed hydroboration of styrene with catecholborane, and good results were obtained with the TADDOL-derived phosphite (R,R)-L9 (Scheme 8). 42 Scheme 7 O R 1 R 2 O P O O O M e M e A r A r A r A r R O H R 1 R 2 1 .…”

Section: Hydroborations and Diborationsmentioning

confidence: 99%

TADDOL-Derived Phosphonites, Phosphites, and Phosphoramidites in Asymmetric Catalysis

Lam¹

2011

Synthesis

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In metal-based asymmetric catalysis, desirable attributes for chiral ligands include low cost, simplicity of synthesis, and ease of variation to enable fine-tuning of a particular transformation. TADDOL-derived phosphonites, phosphites, and phosphoramidites constitute one family of chiral ligand that possesses these features. In recent times, these ligands have excelled in a wide range of catalytic asymmetric reactions. This review article summarizes progress in this area. 10 Miscellaneous Reactions 11 Conclusion

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“…Phophine -phosphite ligands, suitable for screening catalytic system by a modular approach, have been employed in the hydroboration. The phosphine -hosphite ligand 114 derived from taddol was demonstrated to be the best ligand among the modular ligand library to give 91% ee at − 78 ° C with high regioselectivity [56] . Recently, enantioselective hydroboration, of which catalytic system was optimized by screening a library of chiral phosphine -phosphite ligands, was applied in a total synthesis [57] .…”

Section: Asymmetric Hydroboration Of Alkenesmentioning

confidence: 99%

Asymmetric Hydrosilylation of Carbon–Carbon Double Bonds and Related Reactions

Han

Hayashi

2010

Catalytic Asymmetric Synthesis

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INTRODUCTIONAsymmetric hydrometallation of unsaturated substrates catalyzed by chiral transition metal complexes and a subsequent transformation of the hydrometallated compound provide an effi cient asymmetric heterofunctionalization [1] . Transition metal -catalyzed asymmetric hydrosilylation and hydroboration of carbon -carbon unsaturated compounds followed by the oxidative cleavage of the resulting C -Si and C -B bonds give enantiomerically enriched alcohols (Scheme 9.1 ).In this chapter, recent advances in asymmetric hydrosilylation and related hydrometallation reactions catalyzed by chiral transition metal complexes will be reviewed according to the reaction substrates. Not only effi cient catalytic systems with various transition metals and chiral ligands in order to achieve good catalytic activities and enantioselelctivities have been developed extensively but also the reaction scopes of substrates have been broadened to shed a light on new utilizations of asymmetric hydrosilylation during the last decade. Asymmetric hydrosilylation of olefi ns has been extended to palladium -catalyzed hydrosilylation of 1,3 -enynes, giving optically active allenylsilanes and rhodium -catalyzed intramolecular cyclization/hydrosilylation of 1,6 -dienes and 1,6 -enynes giving a cyclic hydrosilylated product. This chapter also discusses transition Catalytic Asymmetric Synthesis, Third Edition, Edited by Iwao Ojima

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Identification of Suitable Ligands for a Transition Metal-Catalyzed Reaction: Screening of a Modular Ligand Library in the Enantioselective Hydroboration of Styrene

Cited by 95 publications

References 5 publications

Rhodium‐Catalyzed Hydroborations and Related Reactions

Rhodium‐Catalyzed Hydroborations and Related Reactions

TADDOL-Derived Phosphonites, Phosphites, and Phosphoramidites in Asymmetric Catalysis

Asymmetric Hydrosilylation of Carbon–Carbon Double Bonds and Related Reactions

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