Iodine isocyanate aziridination

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... 

Iodine isocyanate was used to synthesize the first steroidal aziridine, 2, 3 -iminocholestane (95). from 5a-cholest-2-ene (91). This reaction sequence which is believed to proceed through a three-membered ring iodonium ion (92) illustrates the limitation of pseudohalogen additions for the synthesis of -aziridines. The iodonium complex forms from the least hindered side (usually alpha) and is opened tmK5-diaxially to give a -oriented nitrogen function. The 3a-iodo-2 -isocyanate (93) is converted by treatment with... 

Iodine azide, on the other hand, forms pure adducts with A -, A - and A -steroids by a mechanism analogous to that proposed for iodine isocyanate additions. Reduction of such adducts can lead to aziridines. However, most reducing agents effect elimination of the elements of iodine azide from the /mwj -diaxial adducts of the A - and A -olefins rather than reduction of the azide function to the iodo amine. Thus, this sequence appears to be of little value for the synthesis of A-, B- or C-ring aziridines. It is worthy to note that based on experience with nonsteroidal systems the application of electrophilic reducing agents such as diborane or lithium aluminum hydride-aluminum chloride may yet prove effective for the desired reduction. Lithium aluminum hydride accomplishes aziridine formation from the A -adducts, Le., 16 -azido-17a-iodoandrostanes (97) in a one-step reaction. The scope of this addition has been considerably enhanced by the recent... 

The /i-iodoisocyanate obtained by addition of iodine isocyanate to alkenes can be transformed into aziridines via carbamates, amine salts, or bisulfite addition compounds <67JOC540>. 

On treatment with potassium hydroxide, /3-chlorocarbamates, like jS-iodocar-bamates (see Iodine isocyanate, this volume) give aziridines in 45-75% yield. /3-Chlorocarbamates from terminal olefins on pyrolysis yield 5-alkyloxazolidones in 45-80% yield.3... 

Aziridines can be obtained from alkenes using iodine isocyanate or iodine azide. The product from the latter reaction can be converted into the aziridine via reduction, or into an azirine via elimination of hydrogen iodide and pyrolysis. " ... 

Aziridines are formed from alkenes in a number of multistep processes involving initial reaction with iodine azide, iodine isocyanate or NN-dichlorourethane ... 

---