Sulfur—phosphorus bonds reactions with

A number of non-routine reactions of halogenophosphines are worthy of note. The first aliphatic phosphenium cation featuring a phosphorus-sulfur bond (17) has been obtained by treatment of the chlorophosphine (18) with aluminium trichloride in dichloromethane solution. A new synthesis of acyclic chiral t-phosphines has been developed which employs selective, sequential alkylation of the chloro(amino) phosphines (19) by Grignard and organolithium reagents. The key intermediates (19) are readily prepared by the... 

Further studies by Spry (1975a,b) showed that treatment of the 3-formyl-2-cephem (247) with N-methylhydroxylamine gave the N-meth-ylnitrone (248). Sulfur oxidation and concomitant isomerization of the double bond then yielded the nitrone sulfoxide (249) which upon reaction with phosphorus trichloride in DMF, followed by ester cleavage, provided the 3-carboxamide-3-cephem-4-carboxylic acid (251). Alternatively, the reaction of the nitrone-2-cephem compound (248) with acetic anhydride furnished a mixture of the amide (250) and the imide (252). Both the amide and the imide, after isomerization of the double bond to 3-cephem and ester cleavage, gave the corresponding A -methylamide (251). 

Olefin synthesis starts usually from carbonyl compounds and carbanions with relatively electropositive, redox-active substituents mostly containing phosphorus, sulfur, or silicon. The carbanions add to the carbonyl group and the oxy anion attacks the oxidizable atom Y in-tramolecularly. The oxide Y—O" is then eliminated and a new C—C bond is formed. Such reactions take place because the formation of a Y—0 bond is thermodynamically favored and because Y is able to expand its coordination sphere and to raise its oxidation number. 

While breaking of the carbon-to-phosphorus bond is a nuisance in catalysis with organometallic complexes, the breaking of carbon-to-nitrogen and -to-sulfur bonds is a desired reaction in the oil industry. Hydrodenitrification (HDN) and hydrodesulfurisation (HDS) are carried out on a large scale in order to remove nitrogen and sulfur from the fuel feedstocks. 

Exercise 16-31 Work out reasonable mechanisms for the reactions of phosphorus pentachloride and sulfur tetrafluoride with carbonyl groups. Both phosphorus and sulfur can accommodate five or more) bonded atoms, and the structure of phosphorus pentachloride in the solid state is [PCI4 ] [PCl60]. 

Palladium—phosphorus bonds, palladacycles with, 8, 289 Palladium—sulfur bonds, palladacycles with, 8, 290 PAMAM dendrimers, see Polyaminoamide dendrimers (—)-Pancracine, via Alder-ene reactions, 10, 593 (—)-Papuamine, via Alder-ene reactions, 10, 593 Parahydrogen... 

Recent progress on the use of hypervalent iodine reagents for the construction of heteroatom-heteroatom bonds is reviewed. Reactions of aryl-A3-iodanes with heteroatom substrates derived from third-row elements and beyond are considered first, and an unusual example of heteroatom-heteroatom bond formation with diaryliodonium salts is then discussed. Finally, the use of sulfonylimino(aryl)iodanes for imidations of phosphorus, sulfur, selenium, and arsenic compounds, including enantioselective transformations (S,Se), and alternate hypervalent iodine approaches to N-sulfonylsulfilimines and N-sulfonylarsinimines are summarized. 

Diazaphospholes 4 and 5 are colorless to pale yellow distillable liquids or crystalline solids that are stable to oxidation by air and do not react with elemental sulfur. They are readily hydrolyzed to give the hydrazone from which they originate and phosphorus acid. While only a few reactions of 1/7-1,2,3-diazaphospholes 4 are reported, the chemistry of the 2//-isomers 5 is well studied. In CHEC-II(1996), the following reactions of 1,2,3-diazaphos-pholes are described in detail N-protonation and alkylation, polar addition to the P=C bond and substitution at C-4, cycloaddition reactions, substituent reactions, and the formation of transition metal complexes <1996CHEC-II(4)771>. 

Desulfuration is the term given to removal of sulfur from a molecule. One of the most common desulfuration reactions occurs with sulfur bonded to phosphorus. A common desulfuration reaction is the enzyme-mediated conversion of parathion to paraoxon (see discussion of organophosphate insecticides in Section 18.7) ... 

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