A new direction of ring expansion of 1,2-dialkyldiaziridines in the reactions with arylketenes

Synthesis of monocyclic diaziridines and their fused derivatives

“…[12][13][14][15] Furthermore, diaziridines are prone to ring expansion reactions with electrophilic reagents (ketenes, isocyanates, isothiocyanates, and acylating reagents), which led to the development of new simple methods for the preparation of both known and previously unknown heterocyclic systems. 8,[16][17][18][19][20] And, finally, diaziridines have a high formation enthalpy as a result of the input both of the hydrazine fragment and three-member strained cycle and of low toxicity, which can be potentially useful for replacing hydrazine derivatives in rocket propellants. However some diaziridines had been absolutely or almost inaccessible (e.g.…”

Insertion of carbon disulfide and the nitrile group into the diaziridine ring of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes in ionic liquids catalyzed by BF3 · Et2O

“…The study of the structures of the reaction products showed that the target 1 aryl 6,7 dihydro 1H,5H pyrazolo [1,2 a] [1,2,4]triazoles 8 were produced only in the reactions of compounds 2a-d with nitriles 22a,b (Scheme 10). The yields of bicyclic structures 8a-h also depend on the nature of the substituents in the starting compounds, the nature of the substituents in nitriles 22 having a stronger effect (see Table 3).…”

“…These reactions can be performed only in ionic liquids in the presence of BF 3 •Et 2 O as the catalyst. Based on these reactions, we developed simple one pot methods for the synthesis of 3 aryldihydro 5H pyrazolo[1,2 c][1,3,4]thiadiazole 1 thiones and 1 aryl 6,7 dihydro 1H,5H pyrazolo [1,2 a] [1,2,4]triazoles in high yields. Dipolar intermediates of new reactions, which are direct precursors of the final products, were detected by NMR methods.…”

Diaziridine ring expansion in 6-aryl-1,5-diazabicyclo[3.1.0]hexanes upon reactions with activated olefins in ionic liquids

“…9), respectively. The reactions of 6 aryl 1,5 diaza bicyclo [ 6 ]) in the presence of a BF 3 •Et 2 O catalyst (Scheme 1) proceed through the formation of azomethine imine intermediates 7 with their subsequent cycloaddition to dipolarophiles, leading to 3 (aryl)dihydro 5H pyrazolo [1,2 c] [1,3,4]thiadiazole 1 thiones 5 and 1 aryl 6,7 di hydro 1H,5H pyrazolo[1,2 a] [1,2,4]triazoles 6. 7,8, 10 Earlier, 11 azomethine imines 7, generated similarly from 6 aryl 1,5 diazabicyclo[3.1.0]hexanes 2 in MeCN in the presence of Lewis acids (Et 2 O•BF 3 or In(OTf) 3 ) at 20 °C, were shown to undergo cycloaddition to N arylmaleimides, which are active dipolarophiles with the cis orientation of substituents at the double bond.…”

“…26,27 Experimental IR spectra were recorded on a UR 20 spectrometer in KBr pellets or for neat samples. 1 H, 13 C, and 15 N NMR spectra were recorded on a Bruker AV 600 spectrometer (600.13, 150.90, and 60.81 MHz, respectively) for compounds 10, 10´, and 12 Scheme 5 system. Yields and some physico chemical characteristics of reaction products isolated are given in Table 3, the IR spectro scopic and mass spectrometric data, in Table 4, NMR spectroscopic data, in Table 5.…”