Phosphonium iodide, reduction

Very pure phosphine is formed by the hydrolysis of phosphonium iodide with water, dilute acids or dilute bases 2. 4.107,109-114) or by the reduction of phosphorus trichloride with lithium in diethyl ether 7,us-ii7) Related to the latter is a method for the preparation of phosphine, described in the patent literature, where phosphorus trichloride vapour, diluted with nitrogen, is passed through a column filled with lithium hydride mixed with an inert material, such as sand, NaCl, KCl or similar materials... 

When the reactions of pyrroles and indoles with aldehydes are catalyzed by hydriodic acid, the initially formed carbinols or azafulvenes are reduced to yield the corresponding alkylpyrroles and alkylindoles (68CJC3291,70CJC139). The reductive alkylation of the pyrrole ring, using a range of aliphatic and aromatic aldehydes and ketones, may also be accomplished with phosphonium iodide, with hydrochloric acid and zinc amalgam, or with tin(II) bromide in hydrobromic acid. 

The complex formed on addition of cuprous iodide to a solution of a lithium dialkylamide in ether or tetrahydrofuran is effective in the reductive coupling of allylic halides to give 1,5-dienes with preservation of stereochemistry. This method has been used5 for the stereospecific synthesis of all-trans-squalene and (E,Z,Z,E) squalene from (E,E)- and (Z,JE)-farnesyl bromides, respectively. In an attempted synthesis of (3S)-squalene-2,3-epoxide, 4-[(4R)-2,2,5,5-tetramethyl-l,3-dioxolan-4-yl]butan-2-one (1) and the phosphonium iodide (2) were prepared.6 Unfortu-... 

So-called C-linked calixsugars were prepared by Wittig reaction of the calix[4]arene tetraaldehyde 33 with galactose-6- or ribose-5-phosphorus ylids (obtained in situ from the known phosphonium iodides, Figure 5)70 followed by reduction of the double bonds and deprotection of the hydroxyl groups. Thus, the tetra- and trigalactosides 34c,d (all as P-anomers) and tetra- and tri-L-lyxosides 34 (as a mixture of a- and P-anomers) were obtained. 

Purines are some of the most ubiquitous heterocydes. The quantity of naturally occurring purines produced on the earth is enormous, as 50% of ribo- and 2 -deoxyribonucleic acid (RNA, DNA) bases are purines. Purine is a colorless, crystalline weak base which was first prepared by E. Fischer by zinc dust reduction of 2,6-diiodopurine, which had been obtained from 2,6,8-trichloropurine by reaction with hydrogen iodide and phosphonium iodide. 

The transformation of chloropurines to iodopurines with fuming hydriodic acid and phosphonium iodide is occasionally accompanied by the reduction of one of the chloro groups.Using cold 47% hydriodic acid, the transformation of 6-chloropurine to 6-iodo-purine (Ij can be successfully achieved. 

A variety of processes is available for preparation of phosphine (N.B. very poisonous and flammable) hydrolysis of calcium phosphide7 or aluminum phosphide8 (best if suspended in an inert solvent9,10), white phosphorus,7 a mixture of phosphorus and diphosphorus tetra-iodide,11 or phosphonium iodide 7 thermal disproportionation of phosphorus acid 3,5 or reduction of phosphorus trichloride by lithium tetrahydroaluminate.5... 

The bromine-free hydroscopoline (like dihydroxytropane) is readily oxidized by chromic acid to scopolic acid or l-methylpiperidine-2,6-dicarboxylic acid (65, 68) which has since been synthesized (65, 161, 163). The oxidation of the dihydroxy compound, hydroscopoline, to a hydroxyl-free piperidine derivative would suggest (1) that there is a piperidine nucleus (also that pyridine is formed by the zinc dust distillation of norscopoline (64)) in hydroscopoline (and hence in scopoline) and (2) that the hydroxyls of hydroscopoline are not attached to the piperidine nucleus of this base. The close relationship of scopoline to tropine was first established by the reduction (hydriodic acid and phosphonium iodide at 200°) of hydroscopoline to tropane (167). Dihydroscopoline must be a dihydroxytropane with the hydroxyls, of necessity, located in the pyrrolidine nucleus to account for its oxidation to scopolic acid (LXI —> LXII). 

Berthelot used the method of reduction by heating a substance with concentrated hydriodic acid (in difficult cases saturated at 0° and the tube heated to 280°) in a sealed tube in an oil-bath. He claimed so to have reduced benzene and phenol to hexane, but Baeyer found that benzene is not reduced by heating with phosphonium iodide even at 350°, although toluene, xylene and mesitylene take up 2, 4, and 6 atoms of hydrogen, respectively. 

Baeyer had previously introduced the important method of reduction by heating with zinc dust. He used phosphonium iodide (a good method of preparation of which he described) instead of hydriodic acid and red phosphorus (Berthelot s method) in reductions. He carried out a long research on the reduction of phthalic, isophthalic, and terephthalic acids with sodium amalgam, the results being used in elucidating the structure of benzene (see p. 804). Isophthalic acid derivatives were synthesised by O. Doebner. ... 

Preparative Methods Bu2MeP was initially prepared hy reae-tion of BuMgCl with PCI3, followed by reduction of Bu2PCl with LiAlH4. The so obtained BU2PH was allowed to react with CH3I followed by basic treatment to convert the phosphonium iodide to the free base. 

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