Phosphinic amides cyclic

A series of chiral phosphinous amides bearing pendant oxazoline rings (50, Ri=H,Tr R2=H,Tr, 51, Ri=H,Tr R2=H,Tr and 54, Ri=H,Tr R2=H,Tr in Scheme 41) have been used as ligands in the copper-catalyzed 1,4-addition of diethylzinc to enones. Two model substrates have been investigated, the cyclic 2-cyclohexenone and the acyclic trans-chalcone. The addition products are obtained quantitatively in up to 67% ee [171]. 

Novel cyclic A-(co-haloalkyl)phosphinic amides of the general type 111 cyclize when treated with and the hydrogenphosphonic diamides 112 have also been alkylat-... 

Investigations by Cowley and coworkers and by Soottoo and Baxter have revealed that the reactions between 1,3-dienes and the phosphenium salts 123 (X = NPr 2 or Cl) proceed easily in dichloromethane at 0 °C, to give intermediate cyclic chlorophos-phonium salts (124) (compare structures 97, 119, 120 and 122), several of which were characterized spectroscopically and crystallographically. The highest yields of 124 (X = NPr 2) were achieved when R = R = Me and R = R" = H, and the lowest with the reverse pattern of substitution. The hydrolysis of the salts 124 (X = NR2), using NaOH in aqueous dioxane, yields the cyclic phosphinic amides 125 (X = NR2). 

The nature of alkyl halide and the environment of the phosphorus atom make a substantial contribution to the direction of the reaction. Thus, cyclic phosphites [108], like trialkyl phosphites [110], react with preservation of the coordination of the P(III) phosphorus atom (126-132 ppm). If the alkoxyl group is substituted by amide, alkyl, or aryl, the nucleophilicity of the phosphorus atom in the corresponding amidophosphite (phosphonite) increases in comparison with the trialkyl phosphite. This probably promotes attack by 1 -haloalkyl-2-pyrrolidone at the phosphorus atom and not the oxygen, and this was confirmed experimentally. As a result of the investigated reactions amidophosphonates or ethyl phenyl phosphinates llOa-c were isolated compounds with P(III) were not detected in these cases. 

Bidentate phosphines such as Ph2PCH2PPh2 or Ph2PNHPPh2 form cyclic dinuclear complexes with gold(I). These complexes can be deprotonated with strong bases to give the corresponding methanide or amide complex as shown in equation (7). 

A fourth type of product, a carbamate RNHCOOR , can be obtained from primary or secondary amines, if these are treated with CO, O2, and an alcohol R OH in the presence of a catalyst. " Primary amines react with dimethyl carbonate in supercritical CO2 (see p. 414) to give a carbamate. " Carbamates can also be obtained from nitroso compounds, by treatment with CO, R OH, Pd(OAc)2, and Cu(OAc)2, " and from nitro compounds. " When allylic amines (R2C=CHRCHRNR 2) are treated with CO and a palladium-phosphine catalyst, the CO inserts to produce the p,y-unsa-turated amides (R2C=CHRCHRCONR 2) in good yields. " Ring-expanded lactams are obtained from cyclic amines via a similar reaction (see also, 16-22). Silyloxy carbamates (RNHC02SiR 3) can be prepared by the reaction of a primary amine with carbon dioxide and triethylamine, followed by reaction with triisopropylsilyl triflate and tetrabutylammonium fluoride. ... 

Another example using palladium as the metal center involves the use of a carboxylic phosphine, which was effective in the intra- and intermolecular Heck reaction of a dimethyliodo derivative and of iodobenzene, respectively, with ethyl acrylate [23], For the intramolecular reaction, the cyclic amide was produced in nearly quantitative yields using mild reaction conditions (Eq. 9). A comparison with the TPPTS system reveals the m-TPPTC (m-triphenylphosphine tricarboxylic acid [ Li salt]) analog to be a more efficient system. After one hour of reaction, a 60% conversion was observed compared to approximately 45% with the TPPTS system. 

The only comprehensive and readily-available surveys of thio- and seleno-phosphonic and -phosphinic acids appear to be those in the compilation by Kosolapoff and Maier which appeared during the 1970s, and those in the Houben-Weyl volumes. Some further information relevant to heterocyclic systems which possess endo- or exo-cyclic phosphorus-sulphur bonds has been surveyed by Mann Gefter has also provided a useful compilation of syntheses and data for unsaturated thiophosphonates and related compounds. As in the preceding chapters concerned with the synthesis of the various classes of phosphonic and phosphinic acids, literature surveys have been presented for individual compounds and the field, as a whole, is surveyed annually". In addition. Hall and Inch reviewed the mechanistic implications of changes in stereochemistry following displacement reactions at phosphorus in cyclic phosphorus(V) esters and amides, and in so doing discussed the reaction s of many such thiophosphoryl compounds. 

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