- Double asymmetric induction in the synthesis of enantiomeric α-aminophosphonic acids mediated by sulfinimines
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A double asymmetric induction in the synthesis of α-aminophosphonic acids is described. It involves the nucleophilic addition of anions of enantiomeric dimenthyl phosphites to both (+)-(S)- and (-)-(R)-enantiomers of N-(p-tolylsulfinyl)benzaldimine and subsequent acidic hydrolysis of the adducts formed. The match and mismatch effects were observed.
- Lyzwa, Piotr
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- Organophosphorus chemistry without PCl3: A bridge from hypophosphorous acid to H-phosphonate diesters
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A process for the conversion of hypophosphorous acid (H3PO 2, HPA) and alcohols into various H-phosphonate diesters [(RO) 2P(O)H] is described. The new reaction provides a missing bridge between HPA and important H-phosphonates, completely avoiding the use of PCl3. Nickel chloride or nickel on silica catalyze the oxidative phosphorylation of alkyl phosphinates with various alcohols or water. The reaction is atom economic and avoids the formation of waste products. The previous need for both chlorine and base is completely avoided. Esterification of hypophosphorous acid followed by reaction with another molecule of alcohol under the action of a nickel catalyst provides a green method for the preparation of H-phosphonates. This method entirely avoids the need for any stoichiometric chloride unlike those based on phosphorus trichloride. Copyright
- Fisher, Henry C.,Prost, Lucie,Montchamp, Jean-Luc
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p. 7973 - 7978
(2014/01/06)
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- The difference in reactivity of (-)-mono and dimenthyl vs. diethyl alkylphosphonates in the α-lithiation reaction: Carbanionic synthesis of unknown (-)-dimenthyl 1-iodoalkylphosphonates and their first use in the radical iodine atom transfer addition (I-A
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Unknown (-)-dimenthyl and ethyl (-)-menthyl 1-iodoethylphosphonates were synthesized via 1-lithio derivatives in 85-87% yields. Starting (-)-dimenthyl alkylphosphonates (R = Me, Et, i-Pr) were obtained in the Michaelis-Becker reaction (75-81% yields) and/
- Ba?czewski, Piotr,Szadowiak, Aldona,Bodzioch, Agnieszka,Bia?as, Tomasz,Wieczorek, Wanda M.,Szyrej, Ma?gorzata
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p. 997 - 1009
(2007/10/03)
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- Radical addition reactions of chiral phosphorus hydrides
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Intermolecular radical addition of a (1R,2R,3S,5R)-(-)-pinanediol-derived thiophosphite leads to the diastereoselective formation of organophosphorus adducts. Addition of the intermediate phosphonothioyl radical to electron-rich alkenes or alkynes occurs
- Jessop, Christopher M.,Parsons, Andrew F.,Routledge, Anne,Irvine, Derek J.
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p. 2849 - 2851
(2007/10/03)
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- Asymmetric synthesis of α-substituted alkylphosphonates based on symmetrical dialkyl phosphites
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Chiral C2-symmetrical dialkyl phosphites and C3-symmetrical trialkyl phosphites, derived from (-)-borneol, (-)-menthol, and 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose, were studied as the starting reagents for the preparation of chiral organophosphorus compounds. The reactions of C2-symmetrical dialkyl phosphites and C3-symmetrical trialkyl phosphites with aldehydes and amines or aldehydes are accompanied by asymmetrical induction at the α-carbon atom to yield optically active α-aminoalkylphosphonates or α-hydroxyalkylphosphonates, respectively. The stereoselectivity of the reaction depends on the structure of the starting compounds and the reaction conditions.
- Kolodiazhnyi,Grishkun,Sheiko,Demchuk,Thoennessen,Jones,Schmutzler
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p. 1568 - 1573
(2007/10/03)
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- Sigmatropic -Wittig Rearrangement of α-Allylic-Heterosubstituted Methylphosphonates. Part 3: High Diastereoselectivity in the Rearrangement of Anion of Dimethyl Allyloxymethylphosphonate
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A diastereoselectivity up to 90percent was achieved in the title rearrangement of lithiated allyloxymethylphosphonates, by using the cheaply available chiral dimenthylphosphonyl ester group as stereodirecting auxiliary.The absolute configuration of the newly formed chiral center was assigned by usual chemical conversions.
- Gulea-Purcarescu, Mihaela,About-Jaudet, Elie,Collignon, Noel
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p. 6635 - 6638
(2007/10/02)
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