Diastereoselective Addition of Organomagnesium and Organolithium Reagents to Chiral Trifluoromethyl <i>N</i>‐<i>tert</i>‐Butanesulfinyl Hemiaminals

Grellepois, Fabienne; Jamaa, Abdelkhalek Ben; Gassama, Abdoulaye

doi:10.1002/ejoc.201300890

Cited by 13 publications

(4 citation statements)

References 56 publications

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“…5b, 15 The stereocontrol mode is similar to that in previous precedents for the addition of organolithium reagents to other N ‐ tert ‐butanesulfinyl ketimines 6. 15c, 16 However, in sharp contrast to those reports, an extra Lewis acid additive was not necessary to obtain excellent yields and diastereoselectivities in this study 16a–e. 17…”

Section: The Addition Of Phli To 1 a Under Different Conditions[a]supporting

confidence: 83%

Highly Regio‐ and Diastereoselective Addition of Organolithium Reagents to Chiral Fluoroalkyl α,β‐Unsaturated N‐tert‐Butanesulfinyl Ketimines: A General and Efficient Access to α‐Tertiary Fluoroalkyl Allylic Amines and α‐Fluoroalkyl α‐Amino Acids

Liu

2015

Adv Synth Catal

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Highly regio-and diastereoselective 1,2addition of organolithium reagents to chiral fluoroalkyl a,b-unsaturated N-tert-butanesulfinyl ketimines was developed, providing a general and efficient method for the asymmetric synthesis of structurally diverse a-tertiary fluoroalkyl allylic amines in high yields and with excellent diastereoselectivities (dr up to > 99:1). The synthetic application of the method was demonstrated by the rapid and convenient preparation of challenging a-fluoroalkyl aamino acids with a-tetrasubstituted carbon.Chiral allylic amines are ubiquitous in natural products and pharmaceuticals. [1] They also serve as versatile synthetic intermediates for organic synthesis. [2] Therefore, many efficient methods have been developed for their asymmetric synthesis. [3] On the other hand, owing to the unique properties of fluorine, the incorporation of a fluoroalkyl group into organic compounds may significantly change their physical, chemical, and biological properties. [4] However, only a few methods are available for the asymmetric synthesis of a-fluoroalkyl allylic amines, [5][6][7][8] and most of them are focused on the preparation of chiral a-secondary fluoroalkyl allylic amines. [5] Because of the lack of efficient methods for the construction of fluoroalkyl-containing stereogenic tetrasubstituted carbon centers, strategies for the asymmetric synthesis of a-tertiary fluoroalkyl allylic amines have been far less explored. In 2010, Hu and Liu reported the first asymmetric synthesis of a-tertiary difluoromethyl allylic amines by the nucleophilic difluoromethylations of a,b-unsaturated N-tert-butylsulfinyl ketimines. [6] Recently, Huang et al. reported only a single example of the multistep synthesis of a chiral a-tertiary trifluoromethyl allylic amine from CF 3 -substituted Ntert-butanesulfinyl ketimines. [7a] We also developed efficient methods for the asymmetric synthesis of a-tertiary a-trifluoromethyl-b-nitro and a-cyano allylic amines. [8] Nevertheless, general and efficient methods for the synthesis of a-fluoroalkyl allylic amines bearing a stereogenic tetrasubstituted carbon center are still very rare and remain a significant challenge in organic synthesis.The nucleophilic addition to N-sulfinyl ketimines affords tertiary carbinamines; [9] however, the nucleophilic addition to a,b-unsaturated N-sulfinyl ketimines has rarely been reported. [6,8,10] The biggest challenge in the addition process is the control of both the regioselectivity and diastereoselectivity. Recently, we have successfully developed a series of highly regioselective and diastereoselective nucleophilic addition reactions to trifluoromethyl a,b-unsaturated N-tert-butanesulfinyl ketimines including asymmetric reduction, [5b] aza-Henry reaction, [8a] and Strecker reaction. [8b] In continuation of our interest in the chemistry of fluoroalkyl a,b-unsaturated N-tertbutanesulfinyl ketimines, herein, we report our recent findings on the addition of organolithium reagents to chiral fluoroalkyl a,b-unsaturated N-tert-butanesulfinyl...

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Section: The Addition Of Phli To 1 a Under Different Conditions[a]supporting

confidence: 83%

Highly Regio‐ and Diastereoselective Addition of Organolithium Reagents to Chiral Fluoroalkyl α,β‐Unsaturated N‐tert‐Butanesulfinyl Ketimines: A General and Efficient Access to α‐Tertiary Fluoroalkyl Allylic Amines and α‐Fluoroalkyl α‐Amino Acids

Liu

2015

Adv Synth Catal

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“…In the course of the synthesis of fluorinated amino acids, it was discovered that N , O -acetal precursors were superior for these reactions compared to the unstable fluorinated imine (Scheme ). Additions of allylic organomagnesium reagents exhibited higher diastereoselectivity than additions of other organometallic reagents, which was attributed to a chelated transition state similar to 1051 (Scheme ). ,, In a system with enolizable protons, addition was accompanied by small amounts of a condensation product, 1073 (Scheme ).…”

Section: Additions Of Allylmagnesium Reagents To Imines and Related S...mentioning

confidence: 99%

Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

et al. 2020

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This review describes the additions of allylmagnesium reagents to carbonyl compounds and to imines, focusing on the differences in reactivity between allylmagnesium halides and other Grignard reagents. In many cases, allylmagnesium reagents either react with low stereoselectivity when other Grignard reagents react with high selectivity, or allylmagnesium reagents react with the opposite stereoselectivity. This review collects hundreds of examples, discusses the origins of stereoselectivities or the lack of stereoselectivity, and evaluates why selectivity may not occur and when it will likely occur. CONTENTS 4.2.5. Additions to β-Substituted Aldehydes 4.2.6. Additions to Aldehydes with Distant Chelating Groups 4.3. Additions to Cyclic Ketones 4.3.1. Alkoxy-Substituted Cyclic Ketones 4.3.2. Additions to Alkoxy-Substituted Five-Membered-Ring Ketones 4.3.3. Additions to Alkoxy-Substituted Four-Membered-Ring Ketones 4.4. Additions of Allylmagnesium Halides to Cyclic Hemiacetals 5. Diastereoselectivity of Reactions of Allylmagnesium Reagents with Carbonyl Compounds by Felkin−Anh Control 5.1. Felkin−Anh Stereoselectivity 5.2. Additions to α-Chiral Acyclic Ketones 5.3. Additions to Chiral Exocyclic Ketones and Aldehydes 5.4. Additions of Allylmagnesium Halides to Chiral Cyclic Ketones Controlled by Felkin−Anh Selectivity 5.5. Additions of Allylmagnesium Halides to Chiral Acyclic Aldehydes 6. Diastereoselectivity of Reactions with Carbonyl Compounds by Steric Approach Control 6.1. Steric Approach Control and Stereoselectivity

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“…Hemiaminals 120 react with Grignard reagents 121 to give mainly the corresponding products 122 (Scheme 51). [70] The same reaction was also performed using alkyllithium reagents with similar results. The process seems to take place through the Zimmerman‐Traxler six‐membered transition states TSI and TSII for the allylation process, with coordination between the sulfinyl oxygen of the intermediate imine and the metal.…”

Section: Organomagnesium Compoundsmentioning

confidence: 76%

Chiral N‐tert‐Butylsulfinyl Imines: New Discoveries

Foubelo

Yus

2020

The Chemical Record

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In this account the reactions of chiral N‐tert‐butylsulfinyl imines with organometallic reagents such as organoalkaline (lithium, sodium, potassium and cesium derivatives), organomagnesium, organozinc, organoboron, organoaluminium, organoindium and organosilicon compounds is comprehensively described. The reactivity in all cases is derived to synthetic applications in order to prepare interesting organic nitrogenated molecules, especially in the field of alkaloid compounds.

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Diastereoselective Addition of Organomagnesium and Organolithium Reagents to Chiral Trifluoromethyl N‐tert‐Butanesulfinyl Hemiaminals

Cited by 13 publications

References 56 publications

Highly Regio‐ and Diastereoselective Addition of Organolithium Reagents to Chiral Fluoroalkyl α,β‐Unsaturated N‐tert‐Butanesulfinyl Ketimines: A General and Efficient Access to α‐Tertiary Fluoroalkyl Allylic Amines and α‐Fluoroalkyl α‐Amino Acids

Highly Regio‐ and Diastereoselective Addition of Organolithium Reagents to Chiral Fluoroalkyl α,β‐Unsaturated N‐tert‐Butanesulfinyl Ketimines: A General and Efficient Access to α‐Tertiary Fluoroalkyl Allylic Amines and α‐Fluoroalkyl α‐Amino Acids

Reactions of Allylmagnesium Reagents with Carbonyl Compounds and Compounds with C═N Double Bonds: Their Diastereoselectivities Generally Cannot Be Analyzed Using the Felkin–Anh and Chelation-Control Models

Chiral N‐tert‐Butylsulfinyl Imines: New Discoveries

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