Mannich phospha

Phosphorus-containing Ring Systems. - A range of new chiral oxazaphospholidine oxides 266 and 267 have been synthesised and used as catalysts in asymmetric reductions of ketones with diborane. Mannich-type cyclisation reactions of 5-amino-3-benzylthio-4-cyano(ethoxycarbonyl)pyrazoles with dichlorophenylphosphine and aromatic aldehydes in the presence of cation exchange resin have been used to prepare a number of 6-oxo-6-phospha-4,5,6-trihydroimidazolo[l,2-b]pyrazoles, e.g. 268. Some of these compounds have herbicidal activity and this report is typical of a number of similar ones in the Chinese literature. A number of metallocycles, e.g. 269, have been reported as products from reactions of transient zirconocene-benzyne intermediates with phosphaimines followed by sulfuration or selenation. ... 

In the context of the phospha-Mannich reaction, secondary phosphine oxides were added on the C = N bond of imines in the presence of chiral guanidinium salt catalysts to give the a-aminophosphine oxides in an enantioselective way (Scheme 29). " ... 

The phospha-Mannich condensation of 2- or 4-pyridinecarboxyaldehydes, primary amines and secondary phosphine oxides was carried out in different variations, applying achiral reactants, optically active phosphine oxides and/or (+ )-a-phenyl-ethylamine (Scheme 29). ... 

It was found that in carrying out the Kabachnik-Fields (phospha-Mannich) reaction, there is no need for exotic catalysts, as MW irradiation of the solventless 3-component mixture led to the a-aminophosphine oxides in good yields (Scheme 7A) ... 

The Kabachnik-Fields (phospha-Mannich) reaction has been reviewed, including evidence for imine intermediates via in situ FT-IR studies. Solvent-free microwave conditions are particularly effective, with little call for catalysts. 

In another field, potentially bioactive a-aminophosphonates (51-1) and a-aminophosphine oxides (51-2) were S5m-thesized by the solventless and catalyst-free MW-assisted Kabachnik-Fields (phospha-Mannich) condensation of primary amines, aldehydes/ketones, and >P(0)H species. Earlier preparations utilized special catalysts (e.g., BiNOs [67], phthalocyanine [68], and Lantanoid(OTf)3 [69]) that cannot be regarded eco-friendly species. We proved that under MW conditions, there is no need for any catalyst. Moreover, the S5mtheses can be carried out without the use of a solvent (Scheme 17) [70]. 

Finally, the phospha-Mannich condensation of 1,3,2-dioxaphosphorine 2-oxide (55) paraformaldehyde and secondary amines, including five- and six-membered N-heterocycles, was utilized to make available novel heterocyclic derivatives (56) (Scheme 20) [74]. In these cases, a solvent had to be used. 

SCHEME 22 The synthesis of ring platinum complexes from bis(phospha-Mannich) products. 

G. Keglevich, A. Szekrenyi, M. Sipos, K. Ludanyi, 1. Greiner, Synthesis of cyclic aminomethylphosphonates and aminomethyl-arylphosphinic acids by an efficient microwave-mediated phospha-Mannich approach. Heteroatom Chem. 19 (2008) 207-210. 

E. Balint, E. Fazekas, P. Pongracz, L. Kollar, L. Drahos, T. Holczbauer, M. Czugler, G. Keglevich, N-benzyl and N-aryl bis (phospha-Mannich adducts) synthesis and catalytic activity of the related bidentate chelate platinum complexes in hydroformylation, J. Organomet. Chem. 717 (2012) 75-82. 

The phospha-Mannich condensation of a-, (3- and y-amino acetals, paraformaldehyde and secondary phosphine oxides led to a),(i)-dialko g -all laminomethylphosphine oxides whose reaction with resorcinols or pyrogallol in boiling trifluoroacetic acid afforded (diallg lphosphinoyl-methyl-)(o),a)-diaiylallgrl)ammonium trifluoroacetates (Scheme 41). ... 

Kabachnik-Fields reaction (also called the phospha-Mannich reaction) is one of the oldest and perhaps the most commonly used for the synthesis of a-aminophosphonates. This reaction involves the condensation of primary or secondary amines, earbonyl eompounds (aldehydes and ketones) and >P(0)H speeies, espeeially diallqrl phosphites. 

The Keglevich group has continued to deal with environmentally friendly and P-heterocyclic chemistry. The solid liquid phase alkylation of P=0-functionalised CH acidic compounds was accomplished under phase transfer catalytic and microwave (MW) conditions." a-Hydroxy-benzylphosphine oxides were synthesized by the addition of diphenylphosphine oxide to the carbonyl group of substituted benzaldehydes under MW conditions." The double Kabachnik-Fields (phospha-Mannich) reaction was utilized in the preparation of bis(phosphinoxidomethyl)amines. The Diels Alder cycloadditions of 1,2-dihydrophosphinine oxides and subsequent... 

The double Kabachnik-Fields (phospha-Mannich) reaction of primary amines, two equivalents of paraformaldehyde and the same amount of diphenylphosphine oxide gave bis(diphenylphosphinoylmethyl)amines that were precursors of bidentate P-ligands after double deojq genation... 

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