16965-84-7Relevant academic research and scientific papers
Synthesis, characterization and catalytic properties of magnetic nanoparticle supported guanidine in base catalyzed synthesis of α-hydroxyphosphonates and α-acetoxyphosphonates
Rostami, Amin,Atashkar, Bahareh,Moradi, Darush
, p. 7 - 16 (2013/08/23)
Magnetic nanoparticle Fe3O4-immobilized guanidine (MNPs-Guanidine) as a novel magnetically interphase nanocatalyst was synthesized and characterized. MNPs-Guanidine catalyzed the synthesis of α-hydroxyphosphonates from aldehydes and
Molecular basis of chiral acid recognition by Candida rugosa lipase: X-ray structure of transition state analog and modeling of the hydrolysis of methyl 2-methoxy-2-phenylacetate
Colton, Ian J.,Yin,Grochulski, Pawel,Kazlauskas, Romas J.
experimental part, p. 2529 - 2544 (2011/11/29)
Lipase from Candida rugosa shows high enantioselectivity toward α-substituted chiral acids such as 2-arylpropionic acids. To understand how Candida rugosa lipase (CRL) distinguishes between enantiomers of chiral acids, we determined the X-ray crystal stru
An efficient route to chiral α- and β-hydroxyalkanephosphonates
Pamies, Oscar,Baeckvall, Jan-E.
, p. 4815 - 4818 (2007/10/03)
Enzymatic kinetic resolution of α- and β-hydroxyphosphonates in combination with ruthenium-catalyzed alcohol isomerization led to a successful dynamic kinetic resolution. A variety of racemic hydroxyphosphonates were efficiently transformed to the corresponding enantiomerically pure acetates (ee up to 99% and yield up to 87%).
The synthesis of 1-hydroxy phosphonates of high enantiomeric excess using sequential asymmetric reactions: Titanium alkoxide-catalyzed P-C bond formation and kinetic resolution
Rowe, Bradley J.,Spilling, Christopher D.
, p. 1701 - 1708 (2007/10/03)
Titanium alkoxide-catalyzed asymmetric phosphonylation of aldehydes yields hydroxy phosphonates in moderate to good enantiomeric excess (e.e.s ～70%). The hydroxy phosphonates were acetylated and the acetates were subjected to enzyme-catalyzed kinetic resolution. The non-racemic acetates 2 (predominantly (R)-enantiomer) were hydrolyzed with an (R)-enantiomer-selective lipase, resulting predominantly in the hydrolysis of the (R)-isomer (at 85% conversion) to give the alcohols 3 with high e.e. Alternatively, hydrolysis of the minor enantiomeric (S)-acetate to approximately 20% conversion left the enriched (R)-configured acetate with improved e.e. (>90%). The moderate enantioselectivities obtained in the catalytic P-C bond formation are enhanced during the enzymatic hydrolysis. Furthermore, availability of the non-racemic phosphonates permits the use of less selective enzymes, resulting in higher yields in comparison with the standard resolution of racemic materials.
Phospho-transfer catalysis on the asymmetric hydrophosphonylation of aldehydes
Davies, Stephen R.,Mitchell, Michael C.,Cain, Christopher P.,Devitt, Paul G.,Taylor, Roger J.,Kee, Terence P.
, p. 29 - 57 (2007/10/03)
We report here a precise, in situ 31P{1H}-NMR method of assaying enantiopurity of α-hydroxyphosphonate esters, the products of the carbonyl hydrophosphonylation (Pudovik) reaction. This method is based upon a diazaphospholidine chiral derivatising agent (CDA) which satisfies all of the criteria for a precise assay; (i) derivatisation of α-hydroxyphosphonate esters is both rapid and clean, (ii) kinetic resolution is absent and (iii) 31P{1H} chemical shift dispersions are excellent (> 5ppm). Calibration of this assay has been achieved by cross-referencing the 31P{1H}-NMR signals obtained for the CDA-derivatised ester of (MeO)2PC=O)CHPh(OH) to optical rotation measurements from scalemic material obtained upon lipase catalysed hydrolysis (F-AP 15, Rhizopus oryzae) of (MeO)2P(=O)CHPh(OAc). Analysis of NMR chemical shift and coupling parameters for a closely related series of derivatised α-hydroxyphosphonate esters support further configuration assignments on the basis of inference. We report also on the configurational stability of α-hydroxyphosphonate esters in the presence of acids, organonitrogen bases and metal salts. 2H-labelling and carbonyl crossover experiments reveal that low levels of epimerisation (α) of α-hydroxyphosphonate esters is possible under certain conditions of catalysis and within certain limits. A design strategy for the construction of catalyst systems in the Pudovik reaction is outlined based upon a combination of Lewis acidic (E) and Lewis basic (N) sites. Four types of catalyst are outlined, members of two distinct Classes I and II according to the nature of the acid and base sites, along with our investigations of representative examples of each Class. A variety of Class I.1 systems based on β-amino alcohols (one hydrogen bonding E site and one organonitrogen N site), have been assayed in the model reaction between (MeO)2P(O)H and PhCHO. Results suggest that catalysis of the Pudovik reaction is clean and efficient in certain cases but that catalytic activity is strongly dependent upon the nature of the basic (N) nitrogen centre. Moreover, only low levels ( 50% more strongly (K11 0.53 mol-1 dm3) than dimethyl-H-phosphonate (K11 0.34 mol-1 dm3, 298 K) and to catalyse the hydrophosphonylation reaction between these two substrates with a second order rate constant comparable to that of triethylamine (both k2 5.9 × 10-2 mol-1 dm3 h-1, 293 K). However, one of the major limitations of this model is that competitive product inhibition dominates after some 15 turnovers (75% completion). Model studies reveal that hydrophosphonylation catalysis via a nitrogen Lewis base is accelerated up to 10-fold upon the introduction of [Zn(OSO2CF3)2] as co-catalyst. Consequently, Class II.1 systems employ metal salts [Zn(OSO2CF3)2] as Lewis acidic E sites and chiral co-catalysts capable of binding to the metal and also acting as Lewis basic N sites. Such systems catalyse the addition of (MeO)2P(O)H to PhCHO cleanly with modest turnover numbers (2P(O)H to PhCHO to afford (MeO)2P(O)CHPh(OH) with an average turnover rate (over a 1 h reaction time at 298 K) of 115 h-1 compared to ca. 1 h-1 for NEt3 under analogous conditions. Chiral variants are proposed.
Enzymes in Organic Chemistry, Part 1: Enantioselective Hydrolysis of α-(Acyloxy)phosphonates by Esterolytic Enzymes
Li, Yong-Fu,Hammerschmidt, Friedrich
, p. 109 - 120 (2007/10/02)
α-Hydroxyphosphonates (+/-)-3 were prepared and transformed into esters (+/-)-5.Eight lipases as well as pig liver esterase were tested as catalysts for enantioselective hydrolyses of α-(acyloxy)phosphonates in a biphasic system.Two of them proved to be useful.The highest enantioselectivity was obtained with lipase F-AP 15 and α-(acetyloxy)phenylmethylphosphonates (+/-)-5a and (+/-)-5b as substrates.The (S)-enantiomers were exclusively hydrolyzed to give optically pure alcohols (S)-(-)-3a and (S)-(-)-3b.Lipases AP 6 and F-AP 15 were used to prepare phosphonates(S)-(-)-3b, (S)-(+)-3d and (S)-(-)-3e on a preparative scale with an enantiomeric excess of 81percent, 87percent, and 89percent, respectively.The absolute configurations of the α-hydroxyphosphonates were assigned by Horeau's method and 1H NMR spectroscopy of Mosher's derivatives.
