New ligands for asymmetric palladium catalysed allylic substitution reactions. X-ray crystal structures of two enantiomerically pure dihydrobenzazaphosphole-borane complexes

Tetrahedron ◽  
1995 ◽  
Vol 51 (38) ◽  
pp. 10581-10592 ◽  
Author(s):  
Guy Brenchley ◽  
Michael Fedouloff ◽  
Mary F. Mahon ◽  
Kieran C. Molloy ◽  
Martin Wills
Keyword(s):  
Crystal Structures ◽  
Allylic Substitution ◽  
Substitution Reactions ◽  
Enantiomerically Pure ◽  
X Ray

Enantiomerically pure nucleophiles in diastereoselective palladium catalysed allylic substitution reactions

Chirality ◽  
2003 ◽  
Vol 15 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Mark E. Humphries ◽  
Barry P. Clark ◽  
Samantha Regini ◽  
Lara Acemoglu ◽  
Jonathan M.J. Williams
Keyword(s):  
Allylic Substitution ◽  
Substitution Reactions ◽  
Enantiomerically Pure

Synthesis of Racemic and Enantiomerically Pure (R*,R*,R*)-Tris(α-methylbenzyl)phosphane− X-ray Crystal Structures of the Phosphane Oxides and Borane Complexes

2003 ◽  
Vol 2003 (21) ◽  
pp. 4216-4226 ◽  
Author(s):  
Paul Wyatt ◽  
Helen Eley ◽  
Jonathan Charmant ◽  
Berian J. Daniel ◽  
Anob Kantacha
Keyword(s):  
Crystal Structures ◽  
Enantiomerically Pure ◽  
X Ray

Substitution reactions of tetrahydrofuran in [Cr(thf)3Cl3] with mono and bidentate N-donor ligands: X-ray crystal structures of [Cr(bipy)(OH2)Cl3] and [HpyNH2][Cr(bipy)Cl4]

2008 ◽  
Vol 361 (11) ◽  
pp. 3042-3052 ◽  
Author(s):  
Nicholas F. Brennan ◽  
Burgert Blom ◽  
Simon Lotz ◽  
Petrus H. van Rooyen ◽  
Marilé Landman ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Donor Ligands ◽  
Substitution Reactions ◽  
X Ray

scholarly journals Synthesis and Structures of Low-Valent Tungsten Complexes Bearing Chiral Oxazoline-Derived Ligands

1995 ◽  
Vol 50 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Guy C. Lloyd-Jones ◽  
Andreas Pfaltz
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Allylic Alkylation ◽  
Allylic Substitution ◽  
Substitution Reactions ◽  
X Ray ◽  
Carbonyl Ligands ◽  
Tungsten Complexes ◽  
Enantioselective Catalyst ◽  
Low Valent

The synthesis of low-valent tungsten (0 and II) complexes bearing chiral bidentate phosphino- oxazoline or bisoxazoline ligands is described. The structures of four of the complexes have been determined by single crystal X-ray analyses. Tungsten(II)-allyl complexes of the type [W(CO)2(PN)(C3H5)Cl] (PN = phosphino-oxazoline) are fluxional in solution, but can be crystallized as single diastereoisomers. The complex [W(CO)3(PN)(CH3CN)], which also crystallizes as a single diastereoisomer, is readily oxidized in solution and solid state, in stark contrast to analogous compounds bearing four carbonyl ligands [W(CO)4(PN)] or [W(CO)4(NN)] (NN = bisoxazoline) which were found to be stable. [W(CO)3(PN)(CH3CN)] functions as a highly enantioselective catalyst in allylic substitution reactions with dimethyl sodiomalonate, whereas complexes of the type [W (CO)2(PN )(Z -C3H4)X)] (Z = H, Ph; X = Cl, Br) failed to yield allylic alkylation products.

Stereochemical studies on the formation of α,β-epoxysulfones using α-chloro-β-hydroxysulfones of known configuration

1988 ◽  
Vol 66 (11) ◽  
pp. 2870-2879 ◽  
Author(s):  
J. Stuart Grossert ◽  
Subramanian Sotheeswaran ◽  
H. Ranjith W. Dharmaratne ◽  
T. Stanley Cameron
Keyword(s):  
Crystal Structures ◽  
Experimental Results ◽  
Substitution Reactions ◽  
X Ray ◽  
Epoxide Formation

Substitution reactions adjacent to sulfonyl groups are known to proceed with difficulty, and there is evidence to suggest that these may not necessarily proceed by an SN2 pathway. The mechanism of these reactions could be studied in principle by using the conversion of α-chloro-β-hydroxysulfones of known configuration into α,β-epoxysulfones of known configuration. This paper describes results in which this has been attempted. However, the stereochemical aspects of the epoxide formation could not be assigned unequivocally because of the intervention of a very facile "retro-aldol" process when the chlorohydrins are subjected to treatment with bases, although the experimental results do suggest that the reaction does proceed in a regular SN2-like manner, with inversion at carbon. The X-ray crystal structures of two highly substituted α,β-epoxysulfones are presented, thus putting the structures, including stereochemistry, of a range of these compounds on firm ground.

An enantiomerically pure P-stereogenic bisphosphine: (S,S)-ethylenebis[(2-methylphenyl)phenylphosphine] (o-tolyl-DiPAMP)

2014 ◽  
Vol 70 (12) ◽  
pp. 1174-1177
Author(s):  
Wioletta Bendzińska-Berus ◽  
Magdalena Kaik-King ◽  
Gary King ◽  
Urszula Rychlewska
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Research Program ◽  
Structure Determination ◽  
Title Compound ◽  
X Ray Diffraction ◽  
Acta Cryst ◽  
Enantiomerically Pure ◽  
X Ray

In connection with a research program involving the synthesis, structure determination, reactivity and ability to coordinate to metal centres of chiral bisphosphine ligands, we have synthesized and structurally characterized, by means of single-crystal X-ray diffraction analysis, the title compound {systematic name: (S,S)-(ethane-1,2-diyl)bis[(2-methylphenyl)phenylphosphane], abbreviated aso-tolyl-DiPAMP}, C28H28P2. So far, neither the free bisphosphine (DiPAMP) nor analogues that incorporate the ethylenebisphosphine frame have had their crystal structures reported. The investigated compound forms crystals which are isostructural with the bisphosphine dioxide analogue [Kinget al.(2007).Acta Cryst.E63, o3278], despite the involvement of the dioxide in C—H...O(=P) hydrogen bonds and the lack of similar hydrogen bonds in the investigated crystal structure. In both molecules, the P—C—C—P chain is in atransconformation, extended further at both ends by one of the two P—Cipsobonds. The planes of the phenyl ando-tolyl rings attached to the same P atom are nearly perpendicular to one another. Both crystal structures are mainly stabilized by dispersive interactions.

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