Azides alkyl, reaction with alkenes

The use of reductive alkylation conditions has been employed to access tricycles from the azide 353 <2002S242> (Equation 95). Hydroboration of the alkene double bond with dicyclohexylborane followed by reaction with the azide and subsequent elimination of nitrogen and cyclization gave the linear tricyclic diketopiperazine 354 and 355 as a mixture of diastereoisomers. 

Many of the cycloadducts formed from the dipoles in Table 15.3 are unstable, leading to other products. The reaction of alkyl azides with alkenes generates triazolines (15-54), which extrude nitrogen (N=N) upon heating or photolysis to give an aziridine. 

Metal-mediated Schmidt Reactions of Alkyl Azides with Alkenes and Alkynes... 

Organoboranes react with a mixture of aqueous NH3 and NaOCl to produce primary amines. It is likely that the actual reagent is chloramine NH2CI. Chloramine itself,hydroxylamine-O-sulfonic acid in diglyme, and trimethyl-silyl azide " also give the reaction. Since the boranes can be prepared by the hydroboration of alkenes (15-16), this is an indirect method for the addition of NH3 to a double bond with anti-Markovnikov orientation. Secondary amines can be prepared by the treatment of alkyl- or aryldichloroboranes or dialkylchlorobor-anes with alkyl or aryl azides. 

Secondary amines are formed by reaction of trisubstituted boranes with alkyl or aryl azides. The most efficient borane intermediates are monoalkyldichloroboranes, which are generated by reaction of an alkene with BHCl2 Et20.190 The entire sequence of steps and the mechanism of the final stages are summarized by the equation below. 

The radical carboazidation of alkenes has been achieved in water using triethylborane as initiator [118]. This efficient process is complete in one hour at room temperature in an open to air reaction vessel (Scheme 54, Eq. 54a). These new tin-free carboazidation conditions are environmentally friendly and allow to run reactions with an excess of either the alkene or the radical precursor. They are also suitable for simple radical azidation of alkyl iodides as well as for more complex cascade reactions involving annulation processes (Eq. 54b). In both reactions (Eq. 54a and 54b), an excess of triethylborane (3 equivalents) is required to obtain a good yield. This may be an indication that the chain process, more precisely the reaction between the phenylsul-fonyl radical and Et3B, is not efficient. 

Denson (Ref 9) on those a-azidoalkylidenimines which undergo cyclic isomerizations to tet-razoles and Boyer Canter (Ref 15) made a thorough survey of the available information on alkyl and aryl azides. Cirulis Straumanis (Ref 6) prepd a number of new azides of org bases bur none of these azides showed eiqjl props. Schaad (Ref 14) obtd a patent for the manuf of esters of hydrazoic acid based on the reaction of alkenes, cyclic olefins, ary 1-alkenes cycloalkylalkenes with HN3 in the presence of an acid catalyst... 

Alcohols and alkenes react with HN3 to give alkyl azides, which in the course of reaction rearrange in the same way as discussed in reaction 18-14. The Mitsunobu reaction (10-17) can be used to convert alcohols to alkyl azides, and an alternative reagent for azides, (PhO)2PON3, for use in the Mitsunobu is now available. ° ... 

Synthesis of alkyl azides.1 Terminal alkenes and strained cyclic alkenes react with the reagent to give a mercurial intermediate, which on reduction with sodium borohydride gives an azide. Internal olefins do not react. The method is an extension of the hydroxymercuration reaction of Brown (2,265-267). 

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