1,5-Diazocine ring

Adolph and Cichra synthesized a number of polynitroperhydro-1,5-diazocines and compared their properties with the powerful military explosive HMX. A type of Mannich condensation was used to form the 1,5-diazocine rings the condensation of ammonia and methylamine with formaldehyde and bis(2,2-dinitroethyl)nitramine (46) forming diazocines (47) and (48) respectively. 1,3,3,7,7-Pentanitrooctahydro-1,5-diazocine (47) is A-nitrated to 1,3,3,5,7,7-hexanitrooctahydro-l,5-diazocine (52) in near quantitative yield using mixed acid. 

With Retention of the Diazocine Ring System By Reduction of 1,4-Diazocines... 

One of the earliest authentic eight-membered heterocyclic compounds to be described was 6,7-diphenyldibenzo[e,g][l,4]diazocine (212) prepared by Tauber in 1892 by condensation of 2,2 -diaminobiphenyl and benzil. The diazocine ring is opened hydrolytically under vigorous conditions and is reduced to the 5,6,7,8-tetrahydro compound with sodium amal-... 

A quite different approach to the 1,5-benzodiazodne system begins with 1,3-dipolar cycloaddition of a nitrile oxide and an indolenine (78MI51900). The spiroisoxazoline (303) is converted by irradiation in good yield to the 1,5-benzodiazocinone (304). By using TV,TV - alkylenediindoles and bifunctional nitrile oxides, the diazocine ring is incorporated as a repeating unit into a photoconducting polymer. 

There are two general approaches to the construction of the 1,4-diazocine ring from acyclic precursors (1) via intramolecular cyclization of the appropriately functionalized compound with the formation of one C-N or C-C bond, and (2) by intermolecular condensation with the formation of two C-N bonds. 

In an example of a C-C bond formation in the construction of a 1,4-diazocine ring, racemic [2,5]benzodiazocines 67 were synthesized from hydroxylactams 66 via an iV-acyliminium ion-pyrrole cyclization reaction (Scheme 9) <2000H(52)273>. 

In Scheme 63, four further examples of 1,5-diazocines obtained from 1,3-propanediamine derivatives are outlined, although only one was reported in good yields. Thus, iV-(2-aminoethyl)-l,3-propanediamine reacted with methyl allene dicarboxylate to give the diazepinodiazocine 79 in which the double bond can be located either on the diazocine ring or in the diazepine nucleus <1995H(41)1709>. 

Finally, in an accompanying communication, Crombie et al. described an innovative diazocine ring expansion, in which intramolecular transami-dation was used to convert the Homalium alkaloid precursor 180 (R = R1 = H) into the alkaloid dihydroperiphylline (for details, see Section IV,D) (86TL5151). 

An analysis of the system reveals two benzene rings, one pyrazole ring and one 1,3-diazocine ring, the latter ring being the base component according to the fourth criterion. The square brackets [1,3] indicate that the position of the two heteroatoms is not the basis for numbering the whole system. 

Nucleophilic displacement of chloride substituents in the 4- and 7-positions of the 1,2-diazocine ring provide access to a number of substituted analogues. Thus, treatment of 4,7-dichloro-3,8-diphenyl-1,2-diazocine with silver or lead salts of carboxylic acids affords mono- and diacyloxy derivatives in low to good yield <86BCJ1087>, while treatment with succinimide, phthalimide,... 

By far the most common approach to the 1,3-diazocine ring system has been and remains dependent on formation of the aminal functionality through condensation of appropriate one-carbon sources with diamines. Alkylation of a,(u-disulfonamides with methylene bromide affords modest yields (ca. 45%) of perhydrodiazocine derivatives (5 Ar=p-tolyl, phenyl) (Equation (7))... 

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