Triphenylphosphite methiodide

Rydon and co-workers (73) have shown that the reaction of simple alcohols with triphenylphosphite methiodide and triphenylphosphite dihalides gives alkyl halides according to the general scheme. 

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

The reaction is quite susceptible to steric effects since hindered secondary hydroxyl groups were found to be unreactive. The method can therefore be used to selectively replace a primary hydroxyl group by halogen in the presence of more hindered secondary hydroxyl groups in the same molecule. An example (70) is the reaction of 52 with triphenylphosphite methiodide which affords the 6-deoxy-6-iodo derivative 53 (60%) in which the C-2 hydroxyl group remains intact. 

Whereas l,2-0-isopropylidene-5,6-di-0-methyl-D-glucofuranose was found to be unreactive towards triphenylphosphite dibromide, triphenylphosphite methiodide or phosphorus pentachloride, the related methyl 2,5,6-tri-0-methyl-/ -D-glucofuranoside (59), in which the hindrance caused by the ketal group is absent, reacted with triphenylphosphite methiodide to give the 3-deoxy-3-iodo derivative 60 in 31% yield. 

In a similar way, 5-O-acetylthymidine was converted into the 3-deoxy-3-iodo derivative 72 in 55% yield. In this case, the replacement of the hydroxyl group by iodine was presumed to have taken place by retention of the configuration at C-3. The first intermediate in the reaction was proposed to be the phosphonate (70) which rapidly collapses to an O-3-cyclonucleoside (71) and the latter is subsequently attacked by iodide ion to give the product 72. It was also observed (106) that treatment of nucleosides containing a cis vicinal diol grouping such as 5-0-acetyluridine with triphenylphosphite methiodide failed to provide iodinated products but gave phosphonate derivatives instead. 

Compounds 23 and 24 are shown as ionic species, although the contributions of pentacovalent forms, especially in nonpolar solvents, should not be excluded. The reagents have also been referred to as triphenylphosphite methiodide [(PhO)3PMeI] and triphenylphosphite diiodide [(PhO)3PI2],... 

K. Kefurt, J. Jary, and Z. Samek, Reaction of methyl 2,3-O-isopropylidene-ot-L-rhamno-pyranoside with triphenylphosphite methiodide, J. Chem. Soc. Chem. Commun. p. 213 (1969). 

IODIDES Triphenylphosphite methiodide. ISOCYANATES Cyanogen bromide. 

Triphenylphosphite methiodide [(PhO)3P MeI ] and dihalides [(PhO)3P" XX ] (Rydon reagents), which are closely related to the reagents described above, have also been successfully applied to the synthesis of halogeno sugars [50]. 

Methyltriphenoxyphosphonium iodide [1, 697, before Methyltriphenyi phosphonium bromide]. See Triphenylphosphite methiodide (1,1249). 

Dehydration of either erythro- or f reo-l,2-diphenyl-l-propanol, (1) and (2), with triphenylphosphite methiodide in HMPT gives a mixture of a-methyl-stilbenes in which the less stable Z-olefin predominates. Dehydration of (1) and... 

T riphenylphosphine—Diethyl azodi-carboxylate, 280, 645 Triphenylphosphine dibiomide, 645-646 Triphenylphosphine dichloride, 646-647 Triphenylphosphine dihaiides, 647-648 Triphenylphosphine diiodide, 648 Triphenylphosphine ditriflate, 648 Triphenylphosphite methiodide, 649 Triphenyl phosphite ozonide, 435 Triphenyl(prop-2-ynyl)phosphonium bromide, 494 Triphenylsilanol, 655, 656 Triphenylstannane, 649 Triphenyltin hydride, 649 Triphenylvinylsilane, 637 Triphosphopyridine nucleotide, 36-37 Tri- -propyl orthovanadate, 655 Tris-annelation, 410 Ttis(aquo)hexa-fi-acetato-p,-oxotri-ruthenium acetate, 425-426,650 Tris(dimethoxyboryl)methane, 328, 329 Tris(dimethylamino)borane, 554 Trishomocubanone, 108 Tris(neomenthyldiphenylphosphine)-chlororhodium, 416... 

Bromallenes. PBrg added with ice-cooling during 30 min. to a stirred soln. of 9-ethynylfluoren-9-ol in acetic acid -> 9-(bromovinylidene)fluorene. Y 75%, H. Tani and F. Toda, Bull. Chem. Soc. Japan 37, 470 (1964) lodallenes with triphenylphosphite methiodide s. C. S. L. Baker et al., Soc. 1965, 4348. 

Methyl 6-0-(6-deoxy-2,3,4-tri-0-methyl-j8-L-a/ a6mo-hex-5-enopyranosyl)-2,3,4-tri-O-methyl-jS-D-glucopyranoside - which was prepared from methyl 2,2, 3,3, 4,4 -hexa-0-methyl-/S-melibioside by reaction with triphenylphosphite methiodide and dehydroiodination of the 6 -deoxy-6 -iodo derivative - underwent selective... 

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