Aminophosphonates synthesis

The lanthanide triflate remains in the aqueous phase and can be re-used after concentration. From a green chemistry viewpoint it would be more attractive to perform the reactions in water as the only solvent. This was achieved by adding the surfactant sodium dodecyl sulfate (SDS 20 mol%) to the aqueous solution of e.g. Sc(OTf)3 (10 mol%) [145]. A further extension of this concept resulted in the development of lanthanide salts of dodecyl sulfate, so-called Lewis acid-surfactant combined catalysts (LASC) which combine the Lewis acidity of the cation with the surfactant properties of the anion [148]. These LASCs, e.g. Sc(DS)3, exhibited much higher activities in water than in organic solvents. They were shown to catalyze a variety of reactions, such as Michael additions and a three component a-aminophosphonate synthesis (see Fig. 2.44) in water [145]. 

Simple esters cannot be allylated with allyl acetates, but the Schiff base 109 derived from o -amino acid esters such as glycine or alanine is allylated with allyl acetate. In this way. the o-allyl-a-amino acid 110 can be prepared after hydrolysis[34]. The Q-allyl-o-aminophosphonate 112 is prepared by allylation of the Schiff base 111 of diethyl aminomethylphosphonates. [35,36]. Asymmetric synthesis in this reaction using the (+ )-A, jV-dicyclohex-ylsulfamoylisobornyl alcohol ester of glycine and DIOP as a chiral ligand achieved 99% ec[72]. 

OLEKSYSZYN Aminophosphonic acid synthesis Synthesis ol 1-aminoalkanephosphonic and 1-aminoa([Pg.278]

This group was used as a protective group and chiral directing group for the asymmetric synthesis of o -aminophosphonic acids. It is cleaved by acid hydrol-... 

Interesting developments in simple azetidine chemistry continue to be reported. The apparently general acetylative dealkylation of Af-tert-butyl-3-substituted azetidines 6 (R = Bu ) in the presence of boron trifluoride provides a two-step route to azabicyclobutane 7 from 6 (R = Bu, R = Cl). An aqueous solution of 7 reacts with ethyl chloroformate to give 8. Relatively unexplored 3-azetidinones 9 (R = Ac or NO2) are available from 3-acetoxya2Ktidine 6 (R = Ac, R = OAc) which is obtained by acetylative dealkyation of 6 (R = Bu , R = OAc) <96JOC5453>. 3-Substituted azetidines can be utilized in the synthesis of polyfunctional y- and S-aminophosphonic acid derivatives <95TL9201>. 

During the asymmetric synthesis of a-aminophosphonates (14 in Fig. 4.4), numerous attempts to cleave the benzylic C—N bond, involving catalytic or transfer hydrogenolysis, resulted in epimerization at the a-carbon.319... 

Flynn, G.A., Beight, D.W., Bohme, E.H.W., and Metcalf, B.W., The synthesis of fluorinated aminophosphonic acid inhibitors of alanine racemase, Tetrahedron Lett., 285, 1985. 

Campbell, M.M. and Carruthers, N., Synthesis of a-aminophosphonic and a-aminophosphinic acids and derived dipeptides from 4-acetoxyazetidin-2-ones, Chem. Commun., 730, 1980. 

Tyka, R., Novel synthesis of a-aminophosphonic acids, Tetrahedron Lett., 677, 1970. 

Lukszo, J., Kowalik, J., and Mastalerz, R, Advantages of using di(p-methyl-benzyl) hydrogen phosphite in the synthesis of aminophosphonates from aldimines, Chem. Lett., 1103, 1978. 

The beneficial effect of surfactants on enantioselective hydrogenations in water was exploited in the synthesis of a-aminophosphinic and a-aminophosphonic acids. These compounds are stmctural analogues of a-aminocarboxylic acids and their peptides find use as herbicides, bactericides and antibiotics [150,151]. With [Rh(BPPM)(COD)]Bp4 and similar catalysts fast ractions and e.e.-s up to 98% could be obtained in water in the presence of SDS (Scheme 3.12). 

Kabachnik MI, Medved TY (1952) New synthesis of aminophosphonic acids. Dokl Akad Nauk SSSR 83 689-692... 

Van Meenen E, Moonen K, Acke D et al (2006) Straightforward continuous synthesis of alpha-aminophosphonates under microreactor conditions. ARKIVOC i 3I-45... 

The above route for the production of primary aminophosphonic acids was abandoned following their successful synthesis, in good yield and high purity, by the successive debenzylation (H2/Pd/C) hydrolysis (aqueous HC1) of benzylaminoalkylphosphonate diesters (10). 

The first three steps show that the reaction sequence in Figure 14.45 actually provides a widely applicable approach to such a-aminophosphonic acids. The step leading to the acyl azide F, i.e., the nitrite oxidation of an acyl hydrazide (Formula C in Figure 14.45), is as commonly used for the preparation of an acyl azide synthesis as that shown in Figure 14.44. 

J. Huang, R. Chen, An Overview of Recent Advances on the Synthesis and Biological Activity of tt-Aminophosphonic Acid Derivatives, Heteroatom Chem. 2000,11, 480 492. 

Yamauchi, K., Mitsuda, Y., and Kinoshita, M. 1975. Peptides containing aminophosphonic acids 3. Synthesis of tripeptide containing aminomethylphosphonic acid. Bull. Chem. Soc. Jpn. 48 3285-3286. 

Addition of the lithium anion of chloromethylphosphonate to sulfinimine 126 gave a-chloro-P-aminophosphonates 195 in a ratio of 59 41 and 98% total yield.104 The diastereomeric products can be separated and each converted to the corresponding aziridine-2-phosphonates 196, new building chiral blocks for the enantioselective synthesis of a-aminophosphonates 197 and azirinyl phosphonates 198.104... 

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