Neutral Trichlorooxorhenium(V) Complexes Containing New Heterofunctionalized Phosphane Ligands of the Type PN2 and PNO

Correia, João D. G.; Domingos, Ângela; Santos, Isabel

doi:10.1002/1099-0682(200007)2000:7<1523::aid-ejic1523>3.0.co;2-2

Cited by 24 publications

(33 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The synthesis of each required preparation of the appropriate d 5 -or d 10 -ortho-diphenylphosphino benzoic acid (9) to combine with known procedures for amide coupling with (R,R)-cyclohexane diamine. [23] By adaptation of the procedure of Rauchfuss for the synthesis of unlabeled 9 from PPh 3 , [24] the perdeuterodiphenyl derivative d 10 -9 was readily prepared from d 15 -PPh 3 and then coupled with the requisite amines [23,25] The preparation of the benzoic acids (R P )-d 5 -9 and (S P )-d 5 -9, P-chiral through isotopic substitution, proved significantly more challenging. All attempts to adapt known methods for the asymmetric synthesis of P-chiral phosphines using stereospecific displacements of chiral auxiliaries [26] failed.…”

Section: Synthesis Of 2 H-labeled Ligand (Rr)-1mentioning

confidence: 99%

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺

et al. 2009

View full text Add to dashboard Cite

The solution-phase structures of the monomeric forms of the cationic Pd-eta(3)-allyl and Pd-eta(3)-cyclohexenyl complexes [Pd(R,R)-1(eta(3)-C(3)H(5))](+) (7(+)) and [Pd(R,R)-1(eta(3)-C(6)H(9))](+) (8(+)) bearing the trans-cyclohexylenediamine-based Trost 'Standard Ligand' (R,R)-1 have been elucidated by NMR, isotopic labeling and computation. In both complexes, (R,R)-1 is found to adopt a C(1)-symmetric conformation, leading to a concave shape in the 13-membered chelate in which one amide group in the chiral scaffold projects its NH unit out of the concave surface in close vicinity to one allyl terminus. The adjacent amide has a reversed orientation and projects its carbonyl group out of the concave face in the vicinity of the opposite allyl terminus. Stoichiometric and catalytic asymmetric alkylations of [8(+)][X(-)] by MCHE(2) (E = ester, M = 'escort' counterion, X = Pd allyl counterion) show the same selectivities and trends as have been reported for in situ-generated catalysts, and a new model for the enantioselectivity has been explored computationally. Three factors are found to govern the regioselectivity (pro-S vs pro-R) of attack of nucleophiles on the eta(3)-C(6)H(9) ring in 8(+) and thus the ee of the alkylation product: (i) a pro-R torquoselective bias is induced by steric interaction of the eta(3)-C(6)H(9) moiety with one phenyl ring of the ligand; (ii) pro-S delivery of the nucleophile can be facilitated by hydrogen-bonding with the concave orientated amide N-H; and (iii) pro-R delivery of the nucleophile can be facilitated by escort ion (M) binding to the concave orientated amide carbonyl. The latter two opposing interactions lead to the selectivity of the alkylation being sensitive to the identities of X(-) and M(+). The generation of 8(+) from cyclohexenyl ester substrate has also been explored computationally. The concave orientated amide N-H is able to activate the leaving group of the allylic ester by hydrogen bonding to its carbonyl group. However, this interaction is only feasible for the (S)-enantiomer of substrate, leading to the prediction of a powerful kinetic resolution (k(S) >> k(R)), as is found experimentally. This new model involving two regiochemically distinct (NH) and (CO) locations for nucleofuge or nucleophile binding, may prove of broad utility for the interpretation of the selectivity in asymmetric allylic alkylation reactions catalyzed by Pd complexes of (R,R)-1 and related ligands.

show abstract

Section: Synthesis Of 2 H-labeled Ligand (Rr)-1mentioning

confidence: 99%

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺

et al. 2009

View full text Add to dashboard Cite

show abstract

“…N- 3 ] + (M = Re, 99m Tc) were prepared according to published methods [4,11,[16][17][18][19]. 1 H and 31 P NMR spectra were recorded on a Varian Unity 300 MHz spectrometer; 1 H chemical shifts were referenced with the residual solvent resonances relatively to tetramethylsilane and the 31 P NMR chemical shifts with external 85% H 3 PO 4 solution.…”

Section: General Proceduresmentioning

confidence: 99%

“…Recently, we have introduced several heterofunctionalized phosphines, which are able to stabilize Re and Tc in low and intermediate oxidation states [11,12,[16][17][18][19]. 3 ] + anchored by heterofunctionalized phosphines containing PN 2 and PNO donor atom sets [11,12].…”

Section: Introductionmentioning

confidence: 99%

Rhenium and technetium tricarbonyl complexes anchored by 5-HT1A receptor-binding ligands containing P,O/N donor atom sets

Palma¹,

Correia²,

Domingos³

et al. 2004

Journal of Organometallic Chemistry

Self Cite

View full text Add to dashboard Cite

“…125 More recently, Santos et al were isolated as hydrochlorides with protonated terminal amine groups. 126 Upon increasing the ligand-to-metal ratio, the complexation reactions became more complicated owing to deprotonation of NH and OH groups and possible coordination of two ligands per metal centre. 127 When reacted with (Bu 131 Results of model 99m Tc radiolabelling studies with 69 type compounds were reported separately.…”

Section: Phosphinoamides Designed For Use In Biomedicinementioning

confidence: 99%

Phosphino-carboxamides: the inconspicuous gems

Štěpnička

2012

Chem. Soc. Rev.

View full text Add to dashboard Cite

Compounds combining phosphine and carboxamide moieties in their molecules have developed virtually unnoticed into a specific class of highly structurally versatile and tuneable donor molecules finding manifold use in various fields, particularly in coordination chemistry, biomedical sciences and in catalysis. In the latter field, some phosphinoamides became the real privileged ligands and an indispensable part of a standard toolbox for synthetic chemists. This critical review aims to give an overview of the multifaceted chemistry of such compounds, paying attention to both the fundamentals and recent developments in this continuously expanding field.

show abstract

Neutral Trichlorooxorhenium(V) Complexes Containing New Heterofunctionalized Phosphane Ligands of the Type PN2 and PNO

Cited by 24 publications

References 16 publications

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺

Rhenium and technetium tricarbonyl complexes anchored by 5-HT1A receptor-binding ligands containing P,O/N donor atom sets

Phosphino-carboxamides: the inconspicuous gems

Contact Info

Product

Resources

About

Neutral Trichlorooxorhenium(V) Complexes Containing New Heterofunctionalized Phosphane Ligands of the Type PN2 and PNO

Cited by 24 publications

References 16 publications

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η3-Cyclohexenyl Complex [(η3-c-C6H9)Pd(TSL)]+

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η3-Cyclohexenyl Complex [(η3-c-C6H9)Pd(TSL)]+

Rhenium and technetium tricarbonyl complexes anchored by 5-HT1A receptor-binding ligands containing P,O/N donor atom sets

Phosphino-carboxamides: the inconspicuous gems

Contact Info

Product

Resources

About

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺

Structure-Based Rationale for Selectivity in the Asymmetric Allylic Alkylation of Cycloalkenyl Esters Employing the Trost ‘Standard Ligand’ (TSL): Isolation, Analysis and Alkylation of the Monomeric form of the Cationic η³-Cyclohexenyl Complex [(η³-c-C₆H₉)Pd(TSL)]⁺