New Chiral Reagent for Installation of Pharmacophoric (<i>S</i>)‐ or (<i>R</i>)‐2‐(Alkoxyphosphono)‐1‐amino‐2,2‐difluoroethyl Groups

Xie, Chen; Zhang, Lijun; Mei, Haibo; Pajkert, Romana; Ponomarenko, Maxim V.; Pan, Yi; Röschenthaler, Gerd‐Volker; Soloshonok, Vadim A.; Han, Jianlin

doi:10.1002/chem.201600758

Cited by 24 publications

(12 citation statements)

References 40 publications

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“…In the second step, molecular sieves 4 Å were added and the mixture was heated again for 8 h to effect the imine formation. It should be noted that this type of procedure can be used for other imines possessing sensitive substituents, for instance, ‐CF 2 ‐PO(OEt) 2 group …”

Section: Resultsmentioning

confidence: 99%

Development and Evaluation of Different Methods for Preparation of Fluorine‐Containing (R)‐ and (S)‐N‐tert‐Butanesulfinyl–aldimines

et al. 2016

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Section: Resultsmentioning

confidence: 99%

Development and Evaluation of Different Methods for Preparation of Fluorine‐Containing (R)‐ and (S)‐N‐tert‐Butanesulfinyl–aldimines

et al. 2016

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“…This striking structural imbalance is a consequence of an obviously uneven rate of methodological development between aromatic and aliphatic fluorination . Over the last several years, our group was actively involved in the development of new reagents and methods for installation of aliphatic CF 3 , CF 2 , CF‐containing aliphatic moieties and their analogs . Of particular methodological and practical importance was the development of enantioselective detrifluoroacetylative aldol reactions catalyzed by Cu(II)/chiral bidentate bis(oxazoline) ligands .…”

Section: Methodsmentioning

confidence: 99%

Catalytic Enantioselective Cyano‐Trifluoromethylation of Styrenes

et al. 2017

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Reported herein is the catalytic enantioselective cyano‐trifluoromethylation of styrenes allowing a straightforward preparation of a new structural class of fluorine‐containing compounds. We demonstrate that the desired transformation can be successfully realized using catalytic system of Cu(II)/chiral bidentate bis(oxazoline) ligand, TMS‐CN and Togni reagents, as sources of the CN and CF3 groups, respectively. Preliminary results strongly suggest synthetic potential of this method as the target cyano‐trifluoromethylated products can be generally obtained with high chemical yields (59‐90 %) and excellent enantiomeric purity (91‐98 % ee).

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“…With the iR / iS descriptors, to firmly circumvent any confusion or ambiguity, the –CF 3 /–CH 3 groups are declared as the rank‐fixed ligand, ie iR / iS CF3/CH3(3) . The situation becomes yet more convoluted in the case of phosphorous analogs of amino acids because in this case the phosphorous substituent is of greater priority than both the –CF 3 and –NH 2 groups. But the amino acid analog 5 has been specifically designed and intended as a stereochemical equivalent of natural alanine ( 3 ).…”

Section: The Internal Chirality Descriptors Ir and Is And Ire And Isimentioning

confidence: 99%

Internal chirality descriptors iR and iS and ire and isi. A proposed notation to extend the usefulness of the R/S system by retaining the sense of stereochemistry in cases of ligand ranking changes

2018

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The R/S system, universally applied for indicating the absolute configuration of a structure, is extremely adept for conveying the absolute configuration unequivocally. However, it suffers from one limitation, viz that due to CIP priority rules the rankings of the ligands attached to an asymmetric center can be altered upon a change in a ligand leading to a change in the designated configuration even if bonds to the asymmetric center were not actually formed or broken. This means that the sense of stereochemistry in situations such as within a set of compounds where family relationships are of focus or where the sense of the stereochemical course of a reaction is of interest can be lost or confusion may occur. This shortcoming is easily remedied though by defining a fixed ranking for a particular ligand in the system under study, eg, the ligand at which the change has occurred. The configurations are then expressed as iR or iS, akin to the R and S descriptors, for sp -hybridized tetrahedral chiral structures and similarly, as ire and isi faces, akin to the re and si descriptors, for sp -hybridized trigonal prochiral structures. All in all, the notation can be considered as an auxiliary to extend the usefulness of the R/S system. Thus, the proposed iR/iS notation could find profitable use in comparative studies where there is a need to avoid confusion arising from changing assignments due to priority rules or to expedite the ease of comprehension. Moreover, in the current digital age, the facile retrieval of stereochemically clear data by machines is highly desirable-something that the iR/iS notation is readily amenable to.

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New Chiral Reagent for Installation of Pharmacophoric (S)‐ or (R)‐2‐(Alkoxyphosphono)‐1‐amino‐2,2‐difluoroethyl Groups

Cited by 24 publications

References 40 publications

Development and Evaluation of Different Methods for Preparation of Fluorine‐Containing (R)‐ and (S)‐N‐tert‐Butanesulfinyl–aldimines

Development and Evaluation of Different Methods for Preparation of Fluorine‐Containing (R)‐ and (S)‐N‐tert‐Butanesulfinyl–aldimines

Catalytic Enantioselective Cyano‐Trifluoromethylation of Styrenes

Internal chirality descriptors iR and iS and ire and isi. A proposed notation to extend the usefulness of the R/S system by retaining the sense of stereochemistry in cases of ligand ranking changes

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