Enantioselective Conjugate Addition of Dialkylzinc Reagents to Cyclic and Acyclic Enones Catalyzed by Chiral Copper Complexes of New Phosphorus Amidites

Vries, André H.M. de; Meetsma, Auke; Feringa, Bernard

doi:10.1002/anie.199623741

Cited by 339 publications

(136 citation statements)

References 26 publications

(7 reference statements)

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“…[24] In particular for sterically demanding secondary amines, application of the lithiated amines affords higher yields and shorter reaction times. A reversed procedure, especially for bulky (chiral) phosporamidites has been reported too (see Equation 2 in Scheme 2).…”

Section: Full Papers Synthesis and Use Of Chiral Phosphoramiditesmentioning

confidence: 99%

Monodentate Phosphoramidites: A Breakthrough in Rhodium‐Catalysed Asymmetric Hydrogenation of Olefins

et al. 2003

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Monodentate phosphoramidites based on BINOL or substituted BINOL are excellent ligands for the rhodium-catalysed asymmetric hydrogenation of olefins. Very high enantioselectivities were obtained with MonoPhos (7a) the simplest member of this class, a ligand that is prepared in a single step from BINOL and HMPT. Turnover numbers up to 6000 have been obtained in the hydrogenation of dehydroamino acid derivatives. Enantioselectivities in the hydrogenation of dehydroamino acids are solvent dependent; in non-protic solvents they range from 95 ± 99%. Itaconic acid and its dimethyl ester could be hydrogenated with 96 and 94% e.e., respectively. Hydrogenation of aromatic enamides gave the corresponding acylated amines in 86 ± 94% e.e. Several analogous phosphoramidite ligands have been prepared. Surprisingly, bidentate ligands gave poorer results, both in terms of rate as well as enantioselectivity. Taddol-based phosphoramidites led to poor e.e. and slow rates. Methyl substituents at the 3,3'-position of BINOL led to a sharply reduced rate and a somewhat lower enantioselectivity. Bromo substituents at the 6,6'-position led to a slightly reduced rate but little effect was seen on enantioselectivity. Use of octahydro-MonoPhos (11) gave results that were very similar to those obtained with 7a. The rate of the reaction is dependent on the hydrogen pressure, however, the enantioselectivity is not affected. The rate of the dehydroamino acid hydrogenation also increases if the ligand to rhodium ratio is reduced from 2.2 to 1.5 or even to 1.0; yet, there is no deleterious effect on the enantioselectivity. Catalytic activity ceases with L/Rh 3 when dehydroamino acid derivatives were used as substrate. The reaction shows a positive non-linear effect, which confirms the presence of Rh-complexes with more than one ligand. Following the hydrogenation of methyl 2-acetamidocinnnamate with Rh(nbd) 2 BF 4 /7a by electrospray mass spectrometry showed the presence of several rhodium species. Notable are the presence of [Rh(7a)] 3 and [Rh(7a)] 4 . There is at present insufficient evidence to conclude if the active catalytic species carries one or two ligands. In view of the low cost of MonoPhos this invention might well lead to a broader application of asymmetric olefin hydrogenation for the production of enantiopure amino acids and amines.

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Section: Full Papers Synthesis and Use Of Chiral Phosphoramiditesmentioning

confidence: 99%

Monodentate Phosphoramidites: A Breakthrough in Rhodium‐Catalysed Asymmetric Hydrogenation of Olefins

et al. 2003

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“…Important comparison was that the annulation with the same phosphine ligand in the absence of 12 showed no indication of the product formation (Entry 3). While the combined use of common chiral phosphine ligands, such as MOP 38 (13) or BINAP 39 (14) with TBAB was ineffective in promoting the cycloaddition (Entry 4) or inducing stereoselectivity (Entry 5), BINOLderived phosphoramidite 40,41 15 could impart sufficient cata- lytic activity to the corresponding Pd complex (Entry 6). 12 However, the observed poor stereoselectivity could not be improved by a further screening of structurally different chiral phosphoramidites.…”

Section: Resultsmentioning

confidence: 99%

Multiple Absolute Stereocontrol in Pd-Catalyzed [3+2] Cycloaddition of Oxazolidinones and Trisubstituted Alkenes Using Chiral Ammonium–Phosphine Hybrid Ligands

Imagawa

Nagato

Ohmatsu

et al. 2016

Bulletin of the Chemical Society of Japan

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The development of a Pd-catalyzed highly enantio-and diastereoselective [3+2] cycloaddition of 5-vinyloxazolidinones and activated trisubstituted alkenes is described in detail. This protocol for the single-step construction of densely functionalized pyrrolidines with three contiguous stereocenters including vicinal quaternary stereocenters depends on the remarkable ability of phosphine ligands possessing a chiral ammonium ion to promote intermolecular cycloaddition reactions with a precise control of absolute stereochemistry. A series of control experiments show that a chiral ammonium phosphine hybrid ligand enabled the individual, yet simultaneous stereocontrol of each chiral center in the annulation reaction. The reaction mechanism is also discussed with particular focus on the stereodetermining processes.

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“…[12] As we had already observed that 2-dimethylamino-1,3,2-benzodioxaphosphole (DMBP) was a suitable ligand for our catalytic system, [3a] we decided to test some representative chiral phosphoramidites ( Figure 1). [13] The (R,R)-TADDOL-based ligand A afforded the cycloadduct 3a in 10 % yield and with low enantioselectivity (26 %). On the other hand, (R)-MonoPhos L 1 stood out, providing both a good yield (76 %) and a significant ee (63 %).…”

Section: Resultsmentioning

confidence: 99%

“…13 C NMR spectra were recorded at 50 MHz on the same spectrometer and are reported in ppm from CDCl 3 as internal standard (77.0 ppm).…”

Section: ]mentioning

confidence: 99%

Enantioselective Cobalt‐Catalyzed [6+2] Cycloadditions of Cycloheptatriene with Alkynes

Toselli¹,

Martín²,

Achard³

et al. 2008

Adv Synth Catal

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Enantioselective Conjugate Addition of Dialkylzinc Reagents to Cyclic and Acyclic Enones Catalyzed by Chiral Copper Complexes of New Phosphorus Amidites

Abstract: Enantioselective conjugate addition of dialkylzinc reagents to cyclic and acyclic enones catalyzed by chiral copper complexes of new phosphorus amidites Vries, André H.M. de; Meetsma, Auke; Feringa, Bernard

Cited by 339 publications

References 26 publications

Monodentate Phosphoramidites: A Breakthrough in Rhodium‐Catalysed Asymmetric Hydrogenation of Olefins

Monodentate Phosphoramidites: A Breakthrough in Rhodium‐Catalysed Asymmetric Hydrogenation of Olefins

Multiple Absolute Stereocontrol in Pd-Catalyzed [3+2] Cycloaddition of Oxazolidinones and Trisubstituted Alkenes Using Chiral Ammonium–Phosphine Hybrid Ligands

Enantioselective Cobalt‐Catalyzed [6+2] Cycloadditions of Cycloheptatriene with Alkynes

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