Phosphorus derivatives, rearrangement

Beside aromaticity and syntheses there are a number of reactions, such as substitutions, (cyclo)additions, modification of the phosphorus atom, rearrangements, conversion to metallic derivatives and to coordination complexes, etc. that may be of interest due to the unique features. 

Kinetics of reacting I R = H, OMe with nucleophiles such as the enol of pentan-2,4-dione aromatic amines , phosphorus derivatives and some reactive aromatic compounds , and relative rates with substituted (cyclohexadienyl)Fe(GO)3 cation have been examined. These behave as classically expected, but in contrast to 1-or 2-OMe, a 3-OMe increases rate through its inductive effect. The kinetics agree with electrophilic substitution with the possible intermediacy of n complexes " . Because aryl (N-diene)Fe(CO)3 complexes can rearrange by dissociation into C-aryl derivatives", intermediates could also involve reaction with an N of an indole or a MeO (oxonium cation) of MeO-aromatics. 

Alkylation of Phosphorus Derivatives. The formation of diethyl phosphite anions has been achieved successfully with KHMDS and LiHMDS. The following reaction with acid chlorides is strongly influenced by the counter-ion, as only the rearrangement product was observed with the lithium base, whereas the desired hydroxybisphosphate was the major product when using the potassium base (eq 48). 

The silyl substituted dithiol (Mc3SiSCF2)2, prepared from the sulphenyl chloride CISC2F4SCI (4) and (Mc3Si)2Hg, reacts with the dichlorides RECI2 (E = P, As) to give the heterocycle, the phosphorus derivative undergoing a Michaelis-Arbuzov rearrangement, but not the arsenic one (equation 12). These heterocycles also result directly from (4) and the bis-silyl phosphine or arsine. ... 

Keywords. Phosphorus and sulfur derivatives, Dithioesters, Hetero Diels-Alder, Sigmatropic rearrangements. Chiral ligands... 

Direct metallation of o-halogenophenoxyelement derivatives of silicon, tin, and phosphorus leads to an unstable metallated intermediate which undergoes a rapid 1,3-rearrangement under element-carbon bond formation. This type of reaction seems to be a general method for the synthesis of hydroxyphenyl element derivatives [1-4], We have studied the influence of different organoelement groups on the reaction pathway. The yield increases in the sequence R3Sn < R2P < RjSi P(0)(0R)2. 

Detailed investigations of the chemical reactivity of the diketiminato-stabilized phosphenium cations like 28 (Scheme 17) are to date rare and include only two reports dealing with the substitution and reduction of P-halogen-derivatives. Thus, reaction of 28 (X=Br) with sodium hydroxide in toluene was reported to proceed with displacement of the halide substituent at phosphorus and conservation of the heterocyclic ring to give a mixture of bromide and triflate salts containing a P-hydroxy-substituted cation, both of which were isolated in small yields [89], The products are remarkable as they represent one of very few examples of a stable phosphinous acid which does not rearrange to the tautomeric secondary phosphine oxide. Potassium reduction of the P-chloro-substituted derivative 34 produced the... 

Thus, unlike a-oxyalkylphosphines and their derivatives, which undergo an oxidative rearrangement on heating, P,B-containing heterocycles are transformed into compounds with tricoordinated phosphorus and boron atoms. 

Methyl P-bromomethyl-A-r-butylphosphonamidate (360) has been found to rearrange upon treatment with methoxide to give dimethyl f-butylaminomethylphosphonate (362) and dimethyl iV-r-butyl-iV-methylphosphoramidate (363). The authors have proposed that the products are derived from an azaphosphiridine oxide intermediate (361) by nucleophilic attack at phosphorus and cleavage of the P-N or P-C bond, respectively. ... 

Cavell and Dobbie (214-216) have suggested that halogen transfer rearrangements in trifluoromethylphosphines arise from interactions of nonbonding fluorine p orbitals with vacant d orbitals on phosphorus. Such an explanation is consistent with observations for the Groups IV and V pentafluorophenyl derivatives, exclusive of carbon and nitrogen, and similarly fits the behavior of boron with its vacant p orbital. 

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