The Behaviour of Nitrilimines Towards Ethyl Isocyanoacetate

1,2,3‐ and 1,2,4‐triazolium salts, pyrazoles, and quinoxalines from diarylnitrilimines and isocyanides: A study of the scope

“…the parent diphenylnitrilimine (2 a) (including the tolyl derivatives 2 b , c) and two types of alkyl isocyanides (3 a and 3 b , c), the present study is extended to nitrilimines 2 that bear an electron-donator or -acceptor group at the phenyl substituent such as 2 d -g and to isocyanides 3 that have for Z a t e rtalkyl (3 d , e) or an aryl group (3 g -k). The behaviour of 2 towards an isocyanide having an activated αm e t h y l e n e group (3 f) [3] and also complementary work on C-a c y l -Narylnitrilimines [4] has been reported recently. In both cases there are major deviations in reactivity so that products different from the title classes were obtained.…”

“…As it becomes apparent from Table 1, all pairs of reactants 2 and 3 (given in the form of 4) produce complex mixtures, which is especially true of runs conducted after method B. To provide an overall picture, the results from previous work [1][2][3] are listed, too. 1,2,3-Triazolium Salts 6.…”

Four-membered rings from isocyanides: Developments since the mid 1980s

“…Nitrile imines: Detailed studies on the behavior of N-aryl nitrile imines towards isocyanides [28][29][30][31][32] have shown that the title reaction occurred under certain conditions. 29,31,32 Best suited are nitrile imines bearing a donor-substituted phenyl group at the terminal nitrogen like 34, they gave cycloadducts 36 with a wide variety of isocyanides (Scheme 8).…”

“…29,31,32 Best suited are nitrile imines bearing a donor-substituted phenyl group at the terminal nitrogen like 34, they gave cycloadducts 36 with a wide variety of isocyanides (Scheme 8). 31,32 These four-membered rings, however, eluded isolation, but their formation could be inferred from products formed by [2+2] cycloreversion into benzonitrile and a carbodiimide (37), by ring expansion to a quinoxaline (38), and finally by [2+2] cycloreversion of the secondary adduct 39 into 37 and a 1,2,4-triazole (40). Besides these compounds products such as 41-45 were found; formally, they derive from the linear adduct 35 which in the case R = t-Bu could be detected spectroscopically.…”

“…33 Compared to 34, the proclivity of its N-phenyl analog to undergo a [1+3] cycloaddition is low, 29 and with Ar = 4-NO 2 C 6 H 4 there were no indications at all. 32 This failure applies also to nitrile imines having an acceptor group at the C-terminus like an acyl 31 or a 4-nitrophenyl substituent. Azomethine imines: In contrast to the aryl functionalized CNN moiety in 46a which, using tertbutyl isocyanide, was earlier cyclized to a 1,2-diazetidine ring (47), 2 the acyl group in the congener 46b, as shown recently, confers upon the molecule a 1,5-dipolar character which led to the formation of a 1,3,4-oxadiazine cycle (48) (Scheme 9).…”