Highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by Ru(<scp>ii</scp>)<scp>–</scp>Pheox complexes

Kotozaki, Manato; Chanthamath, Soda; Fujisawa, Ikuhide; Shibatomi, Kazutaka; Iwasa, Seiji

doi:10.1039/c7cc05951e

Cited by 17 publications

(6 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A number of enantioenriched aryl‐substituted substrates ( 4 a – 4 f ) were readily prepared using Iwasa's Ru‐catalyzed asymmetric cyclopropanation of alkenes with α‐diazomethyl aryl sulfones (Scheme , Method A) . Using our α‐hydroxylation conditions, highly enantioenriched cyclopropanone equivalents 5 a – 5 f were obtained in moderate to excellent yields as single diastereomers with retention of configuration at the α‐position, as evidenced by X‐ray crystallographic analysis ( 5 a ) .…”

Section: Resultsmentioning

confidence: 99%

Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β‐Lactams

et al. 2020

View full text Add to dashboard Cite

Cyclopropanone derivatives have long been considered unsustainable synthetic intermediates because of their extreme strain and kinetic instability.R eported here is the enantioselective synthesis of 1-sulfonylcyclopropanols,a ss table yet powerful equivalents of the corresponding cyclopropanone derivatives,bya-hydroxylation of sulfonylcyclopropanes using ab is(silyl) peroxide as the electrophilic oxygen source. This work constitutes the first general approach to enantioenriched cyclopropanone derivatives.B oth the electronic and steric nature of the sulfonyl moiety,w hich serves as ab aselabile protecting group and confers crystallinity to these cyclopropanone precursors,w ere found to have ac rucial impact on the rate of equilibration to the corresponding cyclopropanone.T he utility of these cyclopropanone surrogates is demonstrated in amild and stereospecific formal [3+ +1] cycloaddition with simple hydroxylamines,l eading to the efficient formation of chiral b-lactam derivatives.

show abstract

Section: Resultsmentioning

confidence: 99%

Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β‐Lactams

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Iwasaa employed Ru(II)-Pheox complex ( 574 ) for the highly stereoselective cyclopropanation of alkenes ( 577 ) with various diazo precursors ( 578 / 580 / 583a ) (Scheme A–C). − The asymmetric cyclopropanation between diethyl diazomethylphosphonate ( 578 ) and a series of alkenes including styrene derivatives, α,β-unsaturated esters, ketones, and amides was carried out to provide the corresponding cyclopropylphosphonate products ( 579 ) in high yields and with excellent diastereoselectivity (up to 99:1 dr) and enantioselectivity (up to 97% ee ) (Scheme A) . Similarly, diazosulfones ( 580 ) reacted with various alkenes including vinyl ethers, vinyl amines, and vinyl carbamates to furnish chiral cyclopropyl sulfones ( 581 ) in high yields (up to 80%) with excellent trans -selectivity and enantioselectivity (up to 96% ee ) (Scheme B) . An asymmetric synthesis of various trifluoromethyl cyclopropanes ( 584 ) was achieved in high yields with excellent diastereoselectivity (up to 98:2 dr) and enantioselectivity (up to 96% ee ) by reacting in situ generated CF 3 CHN 2 ( 583b ) with a range of alkenes including vinyl ferrocene, vinyl ethers, vinyl amines, vinyl carbamates, and dienes (Scheme C) …”

Section: Mono(oxazoline) Ligandsmentioning

confidence: 99%

“…211 Similarly, diazosulfones (580) reacted with various alkenes including vinyl ethers, vinyl amines, and vinyl carbamates to furnish chiral cyclopropyl sulfones (581) in high yields (up to 80%) with excellent trans-selectivity and enantioselectivity (up to 96% ee) (Scheme 179B). 212 An asymmetric synthesis of various trifluoromethyl cyclopropanes (584) was achieved in high yields with excellent diastereoselectivity (up to 98:2 dr) and enantioselectivity (up to 96% ee) by reacting in situ generated CF 3 CHN 2 (583b) with a range of alkenes including vinyl ferrocene, vinyl ethers, vinyl amines, vinyl carbamates, and dienes (Scheme 179 C). 213 In 2012, Iwasaa described the highly enantioselective intramolecular cyclopropanation of trans-allylic diazoacetates (585) and alkenyl diazoketones using a water-soluble Ru(II)/ hydroxymethyl (phenyl)oxazoline catalyst, Ru(II)-hm-Pheox (575) (Scheme 180).…”

Section: Scheme 174 Asymmetric Transfer Hydrogenation Of Ketonesmentioning

confidence: 99%

Further Developments and Applications of Oxazoline-Containing Ligands in Asymmetric Catalysis

et al. 2021

View full text Add to dashboard Cite

The chiral oxazoline motif is present in many ligands that have been extensively applied in a series of important metal-catalyzed enantioselective reactions. This Review aims to provide a comprehensive overview of the most significant applications of oxazoline-containing ligands reported in the literature starting from 2009 until the end of 2018. The ligands are classified not by the reaction to which their metal complexes have been applied but by the nature of the denticity, chirality, and donor atoms involved. As a result, the continued development of ligand architectural design from mono(oxazolines), to bis(oxazolines), to tris(oxazolines) and tetra(oxazolines) and variations thereof can be more easily monitored by the reader. In addition, the key transition states of selected asymmetric transformations will be given to illustrate the features that give rise to high levels of asymmetric induction. As a further aid to the reader, we summarize the majority of schemes with representative examples that highlight the variation in % yields and % ee s for carefully selected substrates. This Review should be of particular interest to the experts in the field but also serve as a useful starting point to new researchers in this area. It is hoped that this Review will stimulate both the development/design of new ligands and their applications in novel metal-catalyzed asymmetric transformations.

show abstract

“…We successfully demonstrated that a series of Ru(II)–Pheox complexes could promote catalytic asymmetric intra- and intermolecular cyclopropanations of a wide variety of olefins and asymmetric Si–H insertion reactions with diazo compounds to give the desired products in high yields with high enantioselectivities. 2 On the other hand, details on the generation of the metal–carbene complex from Ru(II)–Pheox and a diazo compound in the initial stage of the reaction remain scarce. In addition, the crystallinity of the Ru(II)–Pheox complex was low and its X-ray crystal structure has not been reported.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, we reported that (acetonitrile) 4 Ru(II)–phenyloxazoline complex (Ru(II)–Pheox), which has a unique C 1 -symmetric structure, is an efficient catalyst for carbene transfer reactions. We successfully demonstrated that a series of Ru(II)–Pheox complexes could promote catalytic asymmetric intra- and intermolecular cyclopropanations of a wide variety of olefins and asymmetric Si–H insertion reactions with diazo compounds to give the desired products in high yields with high enantioselectivities . On the other hand, details on the generation of the metal–carbene complex from Ru(II)–Pheox and a diazo compound in the initial stage of the reaction remain scarce.…”

Section: Introductionmentioning

confidence: 99%

Ligand Exchange Reaction on a Ru(II)–Pheox Complex as a Mechanistic Study of Catalytic Reactions

et al. 2018

Self Cite

View full text Add to dashboard Cite

A ligand exchange of one of the acetonitrile ligands of the (acetonitrile) 4 Ru(II)–phenyloxazoline complex (Ru(II)–Pheox) by pyridine was demonstrated, and the location of the exchange reaction was examined by density functional theory (DFT) calculations to study the mechanism of its catalytic asymmetric reactions. The acetonitrile was smoothly exchanged with a pyridine to afford the corresponding (pyridine)(acetonitrile) 3 Ru(II)–Pheox complex with a trans orientation (C–Ru–N(pyridine)) in a quantitative yield, and the complex was analyzed by single-crystal X-ray analysis. DFT calculations indicated that the most eliminable acetonitrile is the trans group, which is consistent with the X-ray analysis. The direction of the ligand exchange is thus determined on the basis of the energy gap of the ligand elimination instead of the stability of the metal complex. These results suggested that a reactant in a Ru–Pheox-catalyzed reaction should approach trans to the C–Ru bond to generate chirality on the Ru center.

show abstract

Highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by Ru(ii)–Pheox complexes

Abstract: A highly stereoselective cyclopropanation of various olefins with diazosulfones catalyzed by chiral Ru(ii)-Pheox complexes was developed to give chiral cyclopropyl sulfones in high yields (up to 99%) with excellent trans-selectivity and enantioselectivity (up to 98% ee).

Cited by 17 publications

References 39 publications

Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β‐Lactams

Enantioselective Synthesis of Cyclopropanone Equivalents and Application to the Formation of Chiral β‐Lactams

Further Developments and Applications of Oxazoline-Containing Ligands in Asymmetric Catalysis

Ligand Exchange Reaction on a Ru(II)–Pheox Complex as a Mechanistic Study of Catalytic Reactions

Contact Info

Product

Resources

About