A Mannich reaction of 4 amino 3 R furoxans with paraformaldehyde in 10% aqueous H 2 SO 4 led to the high yields of N,N´ bis(3 R furoxan 4 yl)methylenediamines, whose struc ture (using R = Me as an example) was confirmed by X ray diffraction study. The N,N´ bis (3 R furoxan 4 yl)methylenediamines obtained were nitrated to N,N´ dinitro N,N´ bis (3 R furoxan 4 yl)methylenediamines upon the action of 100% HNO 3 in acetic or trifluoro acetic anhydride.Key words: 4 amino 3 R furoxans, paraformaldehyde, hydroxymethylation, the Mannich reaction, 4 hydroxymethylamino 3 R furoxans, N,N´ bis(3 R furoxan 4 yl)methylenedi amines, N nitration, N,N´ dinitro N,N´ bis(3 R furoxan 4 yl)methylenediamines.Derivatives of methylenebisamines are widely used in synthetic organic chemistry, for example, as aminometh ylating agents, 1 while methylenedinitramine fragments are a part of high energy compounds, in particular, hexogene and octogene. The most common and convenient method for the synthesis of methylenediamine derivatives is con densation of 2 moles of amines with 1 mole of formalde hyde by the Mannich reaction. Conditions for this reac tion vary within a wide range and depend, in particular, on the basicity of amines used. 2 This approach was used for the synthesis of derivatives of various heterocyclic amines and their N,N´ dinitro derivatives, including those derived from aminofurazans, i.e., N,N´ bis(furazanyl)methylene diamines and N,N´ dinitro N,N´ bis(furazanyl)methyl enediamines. 3-7Though, compounds derived from N,N´ bis(furoxan yl)methylenedinitramines can be of interest for the prepa ration of potentially high energy compounds, 8 the Man nich bases from aminofuroxans and their further transfor mations are not described in the literature by now, which is due, by all accounts, to the fact that aminofuroxans with suitable substituents at the second C atom are not easily available. 3 Aminofuroxans, except their 4 aryl deriva tives, 9 are virtually unavailable. However, in the last years new fairly convenient methods for the preparation of func tionally substituted 4 aminofuroxans were developed, 10-12 that allowed one to start an extensive study of their re activity.The present work is devoted to the study of behavior of isomeric 4 and 3 aminofuroxans in the Mannich reac tion with formaldehyde in order to obtain N,N´ bis(fur oxanyl)methylenediamines and their nitration to N,N´ di nitro derivatives. The study was started from 4 amino 3 R furoxans 1a-f with substituents of different types at the C(3) atom of the ring (Scheme 1). Initially, in the synthe sis of target N,N´ bis(3 R furoxan 4 yl)methylenedi Scheme 1 R = Me (a), Ph (b), Ac (c), COOMe (d), CONH 2 (e), CON 3 (f)