Synthesis and Properties of Phosphetanes

Marinetti, Angéla; Carmichael, Duncan

doi:10.1021/cr990135r

Cited by 75 publications

(58 citation statements)

References 174 publications

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“…The phosphetane-borane adduct was much more stable than its phosphirane counterpart, which is in agreement with experimental precedent: on the one hand, it has been reported that the borane adduct of t-butylphosphirane releases borane upon mild heating [36], whereas the borane adducts of various phosphetanes are useful as synthetic intermediates [37]. The lower stability of the phosphirane adduct, compared with the phosphetane adduct, is consistent with the poor donor capacity of phosphiranes in general, which results from the high s character of the phosphorus lone pair [38].…”

Section: Is Polymerization Feasible?supporting

confidence: 90%

Anionic ring‐opening polymerization of small phosphorus heterocycles and their borane adducts: An ab initio investigation

Coote

Hodgson

Krenske

et al. 2007

Heteroatom Chemistry

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Section: Is Polymerization Feasible?supporting

confidence: 90%

Anionic ring‐opening polymerization of small phosphorus heterocycles and their borane adducts: An ab initio investigation

Coote

Hodgson

Krenske

et al. 2007

Heteroatom Chemistry

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“…All products 5 a-i were obtained as colourless oils by removing the solvent in vacuo. (4) ), 2 H;CH Ar(3,5) ), 2 H;CH Ar(2,6) ); 40, H 9.71, N 3.85; found: C 69.41, H 9.69, N 4.00.…”

Section: P{mentioning

confidence: 97%

“…[4] This particularly applies to chiral trivalent phosphorus ligands because they are amongst the most useful ligands in asymmetric catalysis. [5,6] A well-known piece of phosphorus chemistry is the functionalisation of a P À H bond by direct reaction with a twofold excess of formaldehyde under acidic conditions, which leads to the formation of an air-and moisture-stable phosphonium salt. [7,8] Thus, these compounds are more convenient starting points for the synthesis of a ligand library than the highly air-sensitive secondary phosphanes.…”

Section: Introductionmentioning

confidence: 99%

Stitching Phospholanes Together Piece by Piece: New Modular Di‐ and Tridentate Stereodirecting Ligands

Lloret‐Fillol¹,

Kruckenberg²,

Scherl³

et al. 2011

Chemistry A European J

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The modular one-pot synthesis of a large family of bi- and tridentate 2,5-dimethyl- and 2,5-diphenyl-substituted phospholanes employs air-stable chiral phospholanium chloride salts and primary amines or NH(4)Cl as starting materials. These were transformed into the C(2)-symmetric dimethyl- and diphenylphospholane ligands, which reacted with [Rh(cod)(2)]BF(4) (cod=1,5-cyclooctadiene) to yield the rhodium complexes [Rh(L)(cod)]BF(4) (L=bisphospholane ligands). The corresponding trisphospholane complexes, 11 and 12, were obtained in high yields (81 and 92%, respectively), and fully characterised by NMR spectroscopy, mass spectrometry and elemental analysis. Whilst in the C(3)-symmetric complex 11, containing the tridentate 2,5-dimethylphospholane, the ligand is bound symmetrically, different coordination behaviour was found for the diphenyl-substituted complex 12, in which the coordination of only two of the three phospholane moieties to the metal centre was observed. A DFT study at the B3PW91 level established minimum energy structures consistent with experimental findings in solution and in the solid state. The non-coordinated phospholane unit present in 12 allowed further modification of the complex through the coordination of Au(I)-X (X=Cl, C(6)F(5) and tris(trifluoromethyl)phenyl ((F)Mes)) fragments to the pendant phosphane. To investigate the potential of the new ligands, the enantioselective hydrogenation of a series of prochiral olefins as benchmark substrates, using isolated Rh complexes as catalysts, was studied. The substrates included methyl esters of three dehydro-α-acetamido acids and two itaconic acid derivatives. In general good to excellent enantioselectivities (of up to >99% ee) were observed. Ligand backbone modification by coordination of bulky Au-X substituents to the free phospholane unit in complex 12 led to an outstanding enhancement of the catalyst performance and there was a clear correlation between the properties of the complex periphery and the enantioselectivity.

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“…The system can also be made rigid by modification of the ketal portion, as illustrated by 14 and SK-Phos (15). These ligands provided high stereoselection for reductions of enamides and MOM-protected b-hydroxy enamides [81].…”

Section: Diopmentioning

confidence: 99%

“…

23Enantioselective Alkene Hydrogenation: Introduction and Historic Overview

Development of CAMP and DIPAMPDuring the late 1960s, Horner et al [13] and Knowles and Sabacky [14] independently found that a chiral monodentate tertiary phosphine, in the presence of a rhodium complex, could provide enantioselective induction for a hydrogenation, although the amount of induction was small [15][16][17][18][19][20]. The chiral phosphine ligand replaced the triphenylphosphine in a Wilkinson-type catalyst [10,21,22].

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mentioning

confidence: 99%

Enantioselective Alkene Hydrogenation: Introduction and Historic Overview

Ager¹

2006

The Handbook of Homogeneous Hydrogenation

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23Enantioselective Alkene Hydrogenation: Introduction and Historic Overview Development of CAMP and DIPAMPDuring the late 1960s, Horner et al. [13] and Knowles and Sabacky [14] independently found that a chiral monodentate tertiary phosphine, in the presence of a rhodium complex, could provide enantioselective induction for a hydrogenation, although the amount of induction was small [15][16][17][18][19][20]. The chiral phosphine ligand replaced the triphenylphosphine in a Wilkinson-type catalyst [10,21,22]. At about this time, it was also found that [Rh(COD) 2 ] + or [Rh(NBD) 2 ] + could be used as catalyst precursors, without the need to perform ligand exchange reactions [23].Knowles found that the monophosphine CAMP (1a) could provide an ee-value of up to 88% for the reduction of dehydroamino acids. CAMP was an extension of PAMP (1b) that provides ee-values of 50-60% in analogous reactions [24]. At this time, Kagan showed that DIOP (2) (vide infra), where the stereogenic centers are not at phosphorus, could also provide enantioselective induction in an hydrogenation. DIOP also showed that a bisphosphine need not have the chirality at phosphorus, and that good stereoselectivity might result from a C 2 -symmetric ligand. Knowles then developed the C 2 -symmetric ligand DIPAMP (3) [22,25]. The use of Rh-DIPAMP for the synthesis of l-Dopa is well known and is still practiced today [12,22,27]. A number of variations of the DIPAMP structure were investigated for the synthesis of this important pharmaceutical, but the parent remains the best ligand in this class [22].

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Synthesis and Properties of Phosphetanes

Cited by 75 publications

References 174 publications

Anionic ring‐opening polymerization of small phosphorus heterocycles and their borane adducts: An ab initio investigation

Anionic ring‐opening polymerization of small phosphorus heterocycles and their borane adducts: An ab initio investigation

Stitching Phospholanes Together Piece by Piece: New Modular Di‐ and Tridentate Stereodirecting Ligands

Enantioselective Alkene Hydrogenation: Introduction and Historic Overview

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