Enantioselective Hydrogenation and Transfer Hydrogenation of Bulky Ketones Catalysed by a Ruthenium Complex of a Chiral Tridentate Ligand

Diaz‐Valenzuela, M. Belen; Phillips, Scott; Gunn, Mary E.; Clarke, Matthew L.

doi:10.1002/chem.200801929

Cited by 71 publications

(12 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the substituent at this position became too large the enantioselectivity started to fall (Table 3, entries 3 vs 8). It is interesting to note that preparation of hindered 3 ja was particularly effective and that other synthetic methodology, including asymmetric ketone hydrogenation, [16] can find this motif challenging. Finally, we noted that under these conditions acidic functional groups in the aldehyde component were not tolerated including: NH 2 and NHBoc.…”

Section: Resultsmentioning

confidence: 99%

On the Scope of Trimethylaluminium‐Promoted 1,2‐Additions of ArZnX Reagents to Aldehydes

Glynn

Shannon

Woodward

2010

Chemistry A European J

View full text Add to dashboard Cite

A practical asymmetric 1,2-addition of functionalised arylzinc halides to aromatic and aliphatic aldehydes is described by the use of aminoalcohol catalysis in the presence of AlMe(3). The process is simple to carry out, uses only commercially available reagents/ligands and provides moderate to good (80-96 % ee) enantioselectivities for a wide range of substrates. Either commercial ArZnX reagents or those prepared in situ from low cost aryl bromides can be used. In the latter case electrophilic functional groups are tolerated (CO(2)Et, CN). The reaction relies on rapid exchange between ArZnX and AlMe(3) to generate mixed organometallic species that lead to the formation of a key intermediate that is distinctly different from the classic "anti" transition states of Noyori. NMR monitoring and related experiments have been used to probe the validity of the proposed selective transition state.

show abstract

Section: Resultsmentioning

confidence: 99%

On the Scope of Trimethylaluminium‐Promoted 1,2‐Additions of ArZnX Reagents to Aldehydes

Glynn

Shannon

Woodward

2010

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…Given that so many drugs, agrochemicals, materials, and natural products can be disconnected back to enantiopure secondary alcohols, it is of significant importance to extend asymmetric hydrogenation chemistry such that it is effective for every major class of substrate. We have already reported on the reduction of some of these challenging substrates, namely bulky ketones [6,10,11], heterocycle appended (bulky) ketones [10], and certain esters [9]. To achieve this, we developed ruthenium complexes of chiral tridentate P,N,N and P,N,OH ligands (derived from cyclohexane diamine and aminocyclohexanol).…”

Section: Resultsmentioning

confidence: 99%

New phosphine-diamine and phosphine-amino-alcohol tridentate ligands for ruthenium catalysed enantioselective hydrogenation of ketones and a concise lactone synthesis enabled by asymmetric reduction of cyano-ketones

Fuentes

Phillips

Clarke

2012

Chemistry Central Journal

View full text Add to dashboard Cite

Enantioselective hydrogenation of ketones is a key reaction in organic chemistry. In the past, we have attempted to deal with some unsolved challenges in this arena by introducing chiral tridentate phosphine-diamine/Ru catalysts. New catalysts and new applications are presented here, including the synthesis of phosphine-amino-alcohol P,N,OH ligands derived from (R,S)-1-amino-2-indanol, (S,S)-1-amino-2-indanol and a new chiral P,N,N ligand derived from (R,R)-1,2-diphenylethylenediamine. Ruthenium pre-catalysts of type [RuCl2(L)(DMSO)] were isolated and then examined in the hydrogenation of ketones. While the new P,N,OH ligand based catalysts are poor, the new P,N,N system gives up to 98% e.e. on substrates that do not react at all with most catalysts. A preliminary attempt at realising a new delta lactone synthesis by organocatalytic Michael addition between acetophenone and acrylonitrile, followed by asymmetric hydrogenation of the nitrile functionalised ketone is challenging in part due to the Michael addition chemistry, but also since Noyori pressure hydrogenation catalysts gave massively reduced reactivity relative to their performance for other acetophenone derivatives. The Ru phosphine-diamine system allowed quantitative conversion and around 50% e.e. The product can be converted into a delta lactone by treatment with KOH with complete retention of enantiomeric excess. This approach potentially offers access to this class of chiral molecules in three steps from the extremely cheap building blocks acrylonitrile and methyl-ketones; we encourage researchers to improve on our efforts in this potentially useful but currently flawed process.

show abstract

“…In 2009, the Clarke group described the microwave synthesis of new chiral catalyst 306 for the enantioselective hydrogenation and transfer hydrogenation of bulky and poorly reactive ketones. 201 ] 308 with the methyl group in either ortho, meta, or para position was described using three different methods: microwave irradiation (using water as the solvent), solvothermal synthesis (using an autoclave and MeOH as the solvent), and conventional synthesis (at reflux in a MeOH/H 2 O mixture). 202 [Ru 2 Br-(OAc) 4 ] 307 was used as the ruthenium source and o-, m-, or p-toluic acid as ligand precursors (Scheme 80).…”

Section: Microwave Proceduresmentioning

confidence: 99%

Alternative Technologies That Facilitate Access to Discrete Metal Complexes

et al. 2019

View full text Add to dashboard Cite

Organometallic complexes: these two words jump to the mind of the chemist and are directly associated with their utility in catalysis or as a pharmaceutical. Nevertheless, to be able to use them, it is necessary to synthesize them, and it is not always a small matter. Typically, synthesis is via solution chemistry, using a roundbottom flask and a magnetic or mechanical stirrer. This review takes stock of alternative technologies currently available in laboratories that facilitate the synthesis of such complexes. We highlight five such technologies: mechanochemistry, also known as solvent-free chemistry, uses a mortar and pestle or a ball mill; microwave activation can drastically reduce reaction times; ultrasonic activation promotes chemical reactions because of cavitation phenomena; photochemistry, which uses light radiation to initiate reactions; and continuous flow chemistry, which is increasingly used to simplify scaleup. While facilitating the synthesis of organometallic compounds, these enabling technologies also allow access to compounds that cannot be obtained in any other way. This shows how the paradigm is changing and evolving toward new technologies, without necessarily abandoning the round-bottom flask. A bright future is ahead of the organometallic chemist, thanks to these novel technologies. CONTENTS1. Introduction 7530 2. Technologies 7530 2.1. Grinding and Milling 7530 2.2. Microwave Irradiation 7531 2.3. Ultrasound Activation 7531 2.4. Photochemistry 7532 2.5. Continuous Flow 7532 3. Contribution of Each Technology Compared to Classical Syntheses 7533 4. Lithium and Magnesium 7534 4.1. Mechanochemical Access to Grignard Reagents 7534 4.2. Microwave Irradiation for the Synthesis of Magnesium Complexes 7534 4.3. Ultrasonic Procedures 7535 4.4. Continuous Flow Syntheses 7535 5. Groups 2, 3, 4, and 5 7537 5.1. Mechanochemical Procedures for Complexes of Groups 2, 3, and 4 7537 5.2. Microwave Irradiation for the Synthesis of Vanadium Complexes 7537 5.3. Synthesis of Vanadium Complexes Using Ultrasound 7538 6. Group 6 7538 6.1. Mechanosynthesis of Molybdenum and Chromium Complexes 7538 6.2. Microwave Irradiation for the Synthesis of Group 6 Metal Complexes 7539 6.3. Photochemistry for Synthesis of Group 6 Metal Complexes 7543 6.4. Continuous Flow Chemistry for Synthesis of Chromium Complexes 7545 7. Group 7 7545 7.1. Mechanosynthesis of Rhenium Complexes 7545 7.2. Microwave Irradiation for the Synthesis of Group 7 Metal Complexes 7546 7.3. Photochemical Synthesis of Manganese and Rhenium Complexes 7549 8. Group 8 7550 8.1. Synthesis of Iron and Ruthenium Complexes Using Ball Milling 7550 8.2. Microwave Procedures 7552 8.3. Ultrasonic Irradiation for Iron Complexes 7562 8.4. Syntheses of Iron and Ruthenium Complexes Using Photochemistry 7563 8.5. Continuous Flow Conditions to Prepare Iron and Ruthenium Complexes 7566 9. Group 9 7566 9.1. Synthesis of Cobalt and Rhodium Complexes by Mechanochemistry 7566 9.2. Procedures Using Microwave Irradiation 7569 9.3. Photochemical Synthesis of Iridium Complexes 7...

show abstract

Enantioselective Hydrogenation and Transfer Hydrogenation of Bulky Ketones Catalysed by a Ruthenium Complex of a Chiral Tridentate Ligand

Cited by 71 publications

References 56 publications

On the Scope of Trimethylaluminium‐Promoted 1,2‐Additions of ArZnX Reagents to Aldehydes

On the Scope of Trimethylaluminium‐Promoted 1,2‐Additions of ArZnX Reagents to Aldehydes

New phosphine-diamine and phosphine-amino-alcohol tridentate ligands for ruthenium catalysed enantioselective hydrogenation of ketones and a concise lactone synthesis enabled by asymmetric reduction of cyano-ketones

Alternative Technologies That Facilitate Access to Discrete Metal Complexes

Contact Info

Product

Resources

About