Diazocines, perhydro

Since the most common group of 1,3-diazocines is related to cyclic urea 104 (called, for example, perhydro-l,3-diazocine-2-one or N,N -pentamethyleneurea), a separate section is devoted to the synthesis, chemistry, and applications of 104, substituted 104, and related molecules such as thiourea 105, guanidines 106, and carbodiimide 107. 

Perhydro-diazocines 28, for the preparation of l,4-diamino-2,3-diol units that are the central structural elements in numerous biomaterials, were obtained from 1,3-cyclooctadiene, by reaction with diethyl azodicarboxylate (DEAD) to give the bridged 1,2-diazocine 103, which by ozonolysis gave the dialdehyde 104 that underwent... 

In some respects, the nomenclature of 1,4-diazocines is similar to that for the eight-membered ring containing one nitrogen (82AHC115). The completely unsaturated compound, for which there exists two valence tautomeric structures, 5 and 6, is called 1,4-diazocine. The partially saturated derivatives are prefixed dihydro-, tetrahydro-, etc. The totally saturated compound is called perhydro-1,4-diazocine, or 1,4-diazacyclooctane. 

Bicyclic feis(l,2-diazocine) derivative (34 X = N3), prepared from the carboxylic acid (34 X = OH) derived from oxidation of the corresponding bis(perhydro)diazocine, is reported as an initiator for radial block copolymerization reactions <85USP453230i, 85USP4556512), while the exothermic nature of the thermal decomposition of hexahydro derivative (35) suggests this compound to be a promising heat amplification material for thermal transfer printing applications <82USP454814). 

A very low yield (1.2%) of benzodiazocinone (12) is obtained as a minor, undesired side product upon rearrangement of the oxime generated in situ from a tetralone derivative (Equation (17)) <86JHC975>. The Tiemann rearrangement allows the preparation of perhydro-l,3-diazocin-2-one (22) <83JOC1694>, while a modification of this rearrangement provides cyclic carbodiimide (7), also prepared by mercuric oxide oxidation of 2-thione derivative (14) (Scheme 12) <83JOCl694>. 

Ring nitrogens of perhydro-l,4-diazocines may also be alkylated <86FRP2567885> and acylated <89JAP(K)Oiiooi72>. Acid-catalyzed dehydration of hydroxy compound (29) affords the anticipated enamine (33), apparently in high yield <82CPB1579>. 

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