Bromine aziridine synthesis

The alkene pseudohalogen adducts (15) of Scheme 8 are also useful intermediates for aziridine synthesis. These adducts are discussed later in Sections 3.S.6.2-4. The iodine azide and bromine azide adducts may be reduced to aziridines with many reagents recent references report use of lidiium aluminum hydride - and dimethylamineborane. The iodine isocyanate aziridination continues to prove useful, as in Scheme Since the recent reviews, - the mechanism of the triphenylphosphine-based... 

Pashkevich and Khomutov [111] reported the synthesis of aziridines containing polyfluoroalkyl substituents on the aziridine cycle. In the case where RF is CF3, the only reaction product is bis(aziridinyl ketone) 103 (Scheme 1.28). The results also provide information about the reaction mechanism. As well as in [107], it is assumed that the reaction proceeds via the formation of a-bromo-ketones and /5-aminoketones 101 and 102 where the next step is the intramolecular bromine substitution and heterocyclization into quinoxaline 104. But in the case where RF is CF3, the formation of the aziridine cycle is followed by the interaction of the second amino group of the diamine with another molecule of the intermediate 102, leading to compound 103. 

The first step is the photolysis of the azide giving a nitrene which forms a dihydrobenzazirine 13 by a [1+2] cycloaddition with the arene the latter isomerizes yielding 1//-azepine. An alternative synthesis of l//-azepines 14 is based on bicyclic aziridines 15, which are transformed to 14 by addition of bromine to the double bond, two-fold dehydrobromination and valence tautomerization of the resulting 13. The bicyclic aziridines 15 are available from cyclohexa-1,4-dienes via l-alkoxycarbonylamino-2-iodocyclohexenes 16 and their SNi-cyclization [15]. 

NBS is used as a reagent for phenylselenyl activation in a route to aziridines and oxazolidin-2-ones. The synthesis of 5-bromoisoquinoline and 5-bromo-8-nitroisoquinoline has been achieved using NBS. 3-Bromo-A-methylpyrrole can be obtained from A-methylpyrrole by the use of NBS and a catalytic amount of PBrs. A new synthetic route to indoloquinones has appeared in which 2-methoxy-2//-azepine derivatives react with NBS to form 3//-azepines. Convenient methods for the bromination of 3,5-diarylisoxazoles and for the synthesis of... 

The synthesis of the aziridinyl-based core 87 of azinomycin A and B has been described (Scheme 17). The illustrated 6-iodo-6-deoxy-D-glucosamine derivative underwent fragmentation and ring closure to provide aziridine 85. Oxidative cleavage of 85, followed by Wadsworth-Homer elaboration and bromination, afforded 86 which underwent an intramolecular addition-elimination to generate 87.59... 

---