Alkenes iodo azides

Neither aromatic halogens [232,602] nor nitro groups were affected during the reductions of the azido group [232, 247, 602]. a-Iodo azides gave, on reduction, aziridines or alkenes depending on the substituents and on the reagents used [603]. 

In the case of electrophilic addition, the reactions of tricyclic dienes 1 with several electrophilic reagents have been investigated.1 7 Interestingly, some of these compounds undergo addition reactions with remarkable syn stereoselectivity. For example, the reaction of dimethyl tricy-clo[4.2.2.02,5]deca-3,9-diene-7,8-dicarboxylate with iodine azide solution, prepared in situ from an excess of sodium azide and iodine monochloride, in acetonitrile at — 5 C provided the. yyn-4-azido-3-iodo derivative 2 (Table 1) in 90% yield.1,2,4,6 The formation of the 5,>,n-4-azido-3-iodo derivative 2 is thought to be the first example of a syn addition of iodine azide to an alkene.1,2 The formation of the syn-product is best explained by the twist strain theory,8 according to which the syn transition structure A is favored over the an/7-coplanar transition structure B.1... 

The radical azidoselenenylation of alkenes can be achieved by reacting diphenyl diselenide with (diacetoxy)iodo-benzene in the presence of sodium azide. The unusual regiochemistry of this reaction is due to the radical... 

Iodine azide, generally made in situ from ICl and NaNa in MeCN at 0 C, adds readily to alkenes by a similar heterolytic mechanism to INCO. Whereas the trans stereochemistry is generally well established,the regiochemistry of the adduct with 1-phenylcyclohexene has been queried recently it was originally formulated as the l-azido-2-iodo compound (Scheme 86), but base treatment was subsequently shown to yield what appeared to be 6-azido-l-phenylcyclohexene, which would have arisen from the l-iodo-2-azido isomer. However, it has very recently teen shown by 3(X) MHz NMR that the elimination product is in fact 3-azido-l-phenylcyclohexene, derived ultimately (Scheme 86) from the originally proposed l-azido-2-iodo- structure. 

The dipolar cycloaddition of an alkyl azide with an alkene to form an aziridine has been exploited in the total synthesis of the alkaloid ( )-aspidospermidine <20050BC213>. Enone 353 was prepared in 11 steps from 3-ethoxycyclohexenone and coupled to 2-iodo nitrobenzene under Ullman cross-coupling conditions. The acetate group of 354 was hydrolyzed and the resulting alcohol converted to an azide using standard conditions in 75% overall yield. The cycloaddition of the azide with the enone was conducted in refluxing benzene for 3 days. The fused-ring aziridine 355 was the only product isolated. None of the initial dipolar cycloadduct triazoline was observed. The... 

A variety of alkenes undergo azidoiodination with sodium azide, potassium iodide, and Oxone on wet alumina to give azido-iodo compounds regioselectively in high yield (eq 79). These compounds are useful precursors to vinyl azides, amines, and aziridines and are typically synthesized with more expensive and exotic reagents. Similar methods have been used in the iodolac-tonization and iodoetherification of unsaturated carboxylic acids and alcohols to make five- and six-membered lactones, tetrahy-drofurans, and tetrahydropyrans (eq 80). ... 

The intermolecular addition of carbon-centered radicals to unactivated alkenes followed by azidation (a formal carboazidation of alkenes) has been reported. A one-pot procedure similar to the one used for intramolecular reactions gives good results (Scheme 8.28). Slow addition of benzenesulfonyl azide is not necessary because this electrophilic reagent does not react with the initial electrophilic or ambiphilic radicals. Excellent results are obtained with a-iodo and -xanthate esters. a-Bromoacetates give also satisfactory results. The carboazidation process allows to prepare pyrroUdinone derivatives in a straightforward manner (Scheme 8.28, bottom example). A tin-free version of this reaction using triethylborane instead of hexabutylditin has also been reported. ... 

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