Nitryl chloride alkenes

Nitryl chloride (NO2CI) also adds to alkenes, to give p-halo nitro compounds, but this is a free-radical process. The NO2 goes to the less-substituted carbon. Nitryl chloride also adds to triple bonds to give the expected l-nitro-2-chloro alkenes. The compound FNO2 can be added to alkenes by treatment with HF in HNOa or by addition of the alkene to a solution of nitronium tetrafluoroborate (NOJBF4, see 11-2) in 70% polyhydrogen fluoride-pyridine solution (see also 15-37). 

Alkenes react with nitryl chloride to give jS-nitroalkyl chlorides, jS-chloroalkyl nitrites and vic-dichloroalkane products. Nitryl chloride reacts with enol esters to give o -nitroketones. ... 

With excess nitrosyl chloride, a chloronitro product is obtained in certain cases, a wide variety of ste-roid-5-enes giving 5a-chloro-6p-nitro derivatives in good yield (CH2CI2/CG4, to 0 C, 2-24 h). Nitryl chloride adds to terminal alkenes (56-80%) and to aoylic acid derivatives (refs. 239,240 and references cited therein) at temperatures close to amlrient. The reaction iq>peais to be a radical one, the NO2 entering the terminal position whatever the electronic requirement of the alkene. 

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