Nitryl iodide alkenes

Replacement of silver nitrite by inexpensive sodiiunor potassium nitrite enhances the imlity of this process Treatment of alkenes v/ith sodiiun nitrite and iodine in ethyl acetate and water in the presence of ethylene glycol gives conjngatednitroalkenesin49-82% yield The method for generation of nitryl iodide is improved by the treatment of iodme v/ith potassium nitrite complexed v/ith 18-crovm-6 in THF under sonicadon, as shovmin Eq 2 32 ... 

The regioselective addition of nitryl iodide to alkenes, followed by base-induced elimination, gives nitroalkenes. Nitryl iodide is generally prepared by the reaction of AgN02 and iodine. 

The synthetic applications of this reagent to the synthesis of nitroalkenes have been known since the 1960s.60 Nitration of alkenes with nitryl iodide, generated in situ from iodine and silver nitrite, is convenient for the synthesis of P-nitrostyrenes with various functional groups.61 This method is applied to the synthesis of ortho-methoxylated phenylisopropylamines, which are potent serotonine agonists (Eq. 2.31).62... 

The use of the pseudohalogen nitryl iodide, prepared in situ from iodine and silver nitrite, has been found to add to an alkene in what is strictly an anti-Markownikov fashion. The explanation for this lies in that nitryl iodide adds in a radical manner, initially forming the more stable secondary radical after addition of NO2.115 Treatment of 3-0-acetyl-5,6-dideoxy-1,2-0-isopropylidene-a-D-xy/o-hex-5-enofuranose with nitryl iodide was found to afford an unstable adduct, with the nitro group appended to C-6, and iodine attached to the more substituted C-5.116-118 Similarly, treatment of benzyl 2-0-benzyl-3,4-dideoxy-a-D-g/ycero-pent-3-enopyranoside (70, Scheme 19) with nitryl iodide afforded the unstable adduct 71, which, upon exposure to mild base (NaHC03), afforded the eliminated product, namely benzyl 2-0-benzyl-3,4-dideoxy-4-nitro-a-D-g(ycew-pent-3-enopyranoside (72). The eliminated product was then readily converted into benzyl 2-0-benzyl-3,4-dideoxy-(3-L-r/ireo-pentopyranoside (73) by reduction with sodium borohydride. Addition of deuteride using NaBD4 led to axial deuteration atC-3. 

The introduction of a nitro group into the alkenes under consideration may be achieved by addition of nitryl iodide (IN02). In the case of alkene 22, this addition, followed by reduction with sodium borohydride, led32 to 3-deoxy-1,2 5,6-di-0-isopropylidene-3-C-(nitromethyl)-a-D-allofuranose (52). Light-induced addition of 1,3-dioxolane to alkenes 15a and 22 has also been reported.47 The resulting adducts, 53 and 54, respectively, are of value as they contain a potential aldehydo function. 

Nitryl iodide, from iodine with silver nitrite or from NO2 and iodine, adds to alkenes, generally in ether at room temperature, by a radical mechanism. Yields are 50-90%. The products yield nitroalkenes on treatment with base, a sequence used recently in the preparation of intermediates (ArCH—CMeNOa) for amphetamine analogs. The reaction is also a key step in the a-methylenebuty-rolactone synthesis shown in Scheme... 

Nitration. Cyclic conjugated alkenes give nitroalkenes on reaction with nitryl iodide, which is prepared in situ from iodine and KNO, (18-crown-6). 

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