Diazirine ring synthesis

It was not their reactivity but their chemical inertness that was the true surprise when diazirines were discovered in 1960. Thus they are in marked contrast to the known linear diazo compounds which are characterized by the multiplicity of their reactions. For example, cycloadditions were never observed with the diazirines. Especially surprising is the inertness of diazirines towards electrophiles. Strong oxidants used in their synthesis like dichromate, bromine, chlorine or hypochlorite are without action on diazirines. Diazirine formation may even proceed by oxidative dealkylation of a diaziridine nitrogen in (186) without destruction of the diazirine ring (75ZOR2221). The diazirine ring is inert towards ozone simple diazirines are decomposed only by more than 80% sulfuric acid (B-67MI50800). 

The chemical inertness of the three-membered ring permitted many conversions of functional groups in diazirines. Esterifications, cleavage of esters and acetals, synthesis of acid chlorides, oxidation of hydroxy groups to carboxyl groups as well as Hofmann alkenation all left the three-membered ring intact (79AHC(24)63). 

Further examples are the synthesis of 5-cyclodecynone [52][53] and the fragmentation of l,2-epoxy-3-diazirine-5a-androstan-17/ -ol by treatment with sodium iodide and acetic acid. (The A ring is opened between C(2) and C(3) to give the l-oxo-2,3-alkyne derivative) [54],... 

Ch. 2 The Synthesis of the p-Lactam Function Ch. 3 Four-Membered Rings Containing Two Nitrogen Heteroatoms Ch. 4 Diaziridines, 3H-Diazirines, Diaziridinones, and Diaziridinimines Note. See note to Pt. 1. 

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