Phosphines, alkylation hydrogenation

The tertiary phosphine oxides are most commonly prepared by simple oxidation of the parent phosphine with hydrogen peroxide,1 alkylation of a trihalophosphine oxide,2 or by oxidation of an appropriate phosphonium salt by moist silver(I) oxide.3 The simplest and quickest method is the peroxide oxidation of the parent phosphine. Inasmuch as appropriate syntheses... 

Bochwic, B., and Michalski, J., Eormation of C-P bonds by addition of di-alkyl hydrogen phosphonates and alkyl hydrogen phosphinates to activated ethylenic derivatives. Nature, 167, 1035, 1951. 

A variation of the Wittig reaction that can overcome problems with the stereochemical outcome is the Homer-Wittig reaction with phosphine oxides. The oxides are obtained by quatemization of triphenylphosphine and hydrolysis of the phosphonium salt, or by reaction of hthiodiphenylphosphide with an alkyl halide or sulfonate and oxidation of the resulting phosphine with hydrogen peroxide. The derived hthio species react with aldehydes or ketones to give p-hydroxy phosphine oxides, which ehminate on treatment with a base such as sodium hydride or potassium hydroxide to form the alkene. In common with the Homer-Wadsworth-Emmons reaction, the phosphorus by-product is water soluble and easily removed from the product. 

Carbon-phosphorus bonds can be formed by the addition of dialkyl hydrogen phosphites or alkyl hydrogen phosphinates to activated ethylenic compounds. ... 

A convenient method of producing alkyl hydrogen phosphinothionates is by heating a phosphinic ester with P4S10, or by reacting H2S with a phosphonamidite ester or a phosphonous ester. Further treatment of the new ester with sulphuryl chloride replaces the hydrogen with chlorine. 

A useful apphcation of phosphines for replacing a carbonyl function with a carbon—carbon double bond is the Wittig reaction (91). A tertiary phosphine, usually triphenylphosphine, treated with the appropriate alkyl halide which must include at least one a-hydrogen, yields the quaternary salt [1779A9-3] which is then dehydrohalogenated to form the Wittig reagent, methylenetriphenylphosphorane [19943-09-5] an yhde. 

Examples are given of common operations such as absorption of ammonia to make fertihzers and of carbon dioxide to make soda ash. Also of recoveiy of phosphine from offgases of phosphorous plants recoveiy of HE oxidation, halogenation, and hydrogenation of various organics hydration of olefins to alcohols oxo reaction for higher aldehydes and alcohols ozonolysis of oleic acid absorption of carbon monoxide to make sodium formate alkylation of acetic acid with isobutylene to make teti-h ty acetate, absorption of olefins to make various products HCl and HBr plus higher alcohols to make alkyl hahdes and so on. 

Notable examples of general synthetic procedures in Volume 47 include the synthesis of aromatic aldehydes (from dichloro-methyl methyl ether), aliphatic aldehydes (from alkyl halides and trimethylamine oxide and by oxidation of alcohols using dimethyl sulfoxide, dicyclohexylcarbodiimide, and pyridinum trifluoro-acetate the latter method is particularly useful since the conditions are so mild), carbethoxycycloalkanones (from sodium hydride, diethyl carbonate, and the cycloalkanone), m-dialkylbenzenes (from the />-isomer by isomerization with hydrogen fluoride and boron trifluoride), and the deamination of amines (by conversion to the nitrosoamide and thermolysis to the ester). Other general methods are represented by the synthesis of 1 J-difluoroolefins (from sodium chlorodifluoroacetate, triphenyl phosphine, and an aldehyde or ketone), the nitration of aromatic rings (with ni-tronium tetrafluoroborate), the reductive methylation of aromatic nitro compounds (with formaldehyde and hydrogen), the synthesis of dialkyl ketones (from carboxylic acids and iron powder), and the preparation of 1-substituted cyclopropanols (from the condensation of a 1,3-dichloro-2-propanol derivative and ethyl-... 

Phosphine, (2-bromophenyl)dichloro-, 2,991 Phosphine, (w-chloroalkyl)dichloro-, 2, 991 Phosphine, chlorodimethyl-, 2, 991 Phosphine, chloro(dimethylamino)-, 2, 991 Phosphine, chlorodiphenyl-, 2, 990 Phosphine, cyclohexyl(o-anisyl)methyl-rhodium complexes asymmetric hydrogenation, 6, 251 Phosphine, [(dialkylphosphino)alkyl]diphenyl-, 2, 994 Phosphine, dichloromethyl-, 2, 991 Phosphine, dichlorophenyl-, 2, 990 Phosphine, diethylphenyl-, 2, 992 Phosphine, dimethyl-, 2,992 Phosphine, dimethylphenyl-, 2,992 Phosphine, diphenyl-, 2, 992 Phosphine, ethyldiphenyl-, 2, 992 Phosphine, ethylenebis(diethyl-, 2, 993 Phosphine, ethylenebis(diphenyl-, 2,993 Phosphine, ethylenebis(phenyl-, 2,992 Phosphine, ethylidynetris[methylene(diphenyl-, 2,994 Phosphine, [(ethylphenylphosphino)hexyl]diphenyl-, 2, 994... 

Madsen and co-workers have reported an important extension to the amine alkylation chemistry, in which oxidation takes place to give the amide product [13]. A ruthenium NHC complex is formed in situ by the reaction of [RuCl Ccod)] with a phosphine and an imidazolium salt in the presence of base. Rather than returning the borrowed hydrogen, the catalyst expels two equivalents of H. For example, alcohol 31 and benzylamine 27 undergo an oxidative coupling to give amide 32 in good isolated yield (Scheme 11.7). 

In addition, Peruzzini et al. developed, in 2007, iridium complexes of planar-chiral ferrocenyl phosphine-thioether ligands that were tested in the hydrogenation of simple alkyl aryl ketones.These complexes were diastereoselec-tively generated in high yields (85-90%) by addition of the corresponding... 

Scheme 8.33 Hydrogenations of alkyl aryl ketones with ferrocenyl phosphine-thioether ligands.

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