Rydon reagent

Further applications of the reagent with nuclesosides have been examined.170 An interesting observation in the iodination of S -O-tritylthymidine was that a small amount of the 3, 5 -dideoxy-3, 5 -diiodo species was obtained in addition to the expected preponderance of the C-3 iodinated product. Presumably, HI produced during the course of the reaction effected the removal of the acid-sensitive trityl ether. 

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Selective replacement of primary hydroxyl groups in carbohydrates by iodine atoms has been achieved by using the Rydon reagent, namely, methyltriphenoxyphosphonium iodide.368 Treatment of methyl 3,4-O-isopropylidene-jS-D-galactopyranoside with the phosphonium salt in benzene for 48 hours at room temperature yielded 60% of the 6-deoxy-6-iodo derivative,369 and reaction of thymidine, uridine, and 2,2 -anhydrouridine in N,N-dimethylformamide afforded 5 -deoxy-5 -iodo derivatives in yields of 63, 65, and 31%, respectively.370... 

Several other examples of the reaction of carbohydrates with Rydon reagents have been provided by Kochetkov and coworkers.56 Most... 

There are several methods for the conversion of alcohols into iodides using phosphorus-containing reagents. Two important reagents (Rydon reagents) are methyltriphenoxy-phosphonium iodide 6 and iodotriphenoxyphosphonium iodide 7, respectively formed... 

There are many examples of the reaction of carbohydrates with Rydon reagents [16] the reaction is controlled by steric factors. Thus, no reaction occurred between 1,2-0-isopropylidene-5,6-di-0-methyl-a-D-glucofuranose and either 6 or bromotriphenoxyphos-phonium bromide, presumably because of the steric hindrance caused by the trioxabicyclo [3.3.0]octane ring-system, whereas methyl 2,5,6-tri-O-methyl-p-D-glucofuranoside reacted with 6 to give a 3-deoxy-3-iodo derivative in 31% yield. 

The original Rydon reagent [51], methyl triphenoxyphosphonium iodide [(PhO)3P+-Mel-], which was used extensively for the preparation of deoxyiodo sugars [52-54] and nucleosides [41,55-59] is still a reliable and efficient protocol. 

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]. 

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