Diazepines and derivatives

SEVEN MEMBERED SYSTEMS CONTAINING TWO HETEROATOMS 7.3.1 Diazepines and fused diazepines and derivatives... 

Amides [41,44], thioamides [41 ] and amidines [45] are converted into nitriles by the reaction with dichlorocarbenes generated by Makosza s procedure (Table 7.16). Under similar conditions, monosubstituted and A.A-disubstituted ureas are converted into cyanamides (Table 7.17) JV,(V -disubstituted ureas produce carbodi-imides in low yield [41,46,47]. /V-Carbamoyl derivatives of dibenzo[/ /]diazepines and the related 10, l l-oxirane derivatives are converted into the corresponding... 

These are the most widely used routes to 1,3-diazepines and provide easy access to the monocyclic system, 1,3- and 2,4-benzodiazepines, and dibenzodiazepines by the reactions of (113)-(116) (and their derivatives) respectively with 1,1-bis-electrophilic reagents. The use of aldehydes produces the rather unstable fully saturated —NHCH2NH— linkage and has been rarely applied to the synthesis of monocyclic systems. (67AHC(8)2l, p. 40) but provides useful syntheses of 1,3-benzodiazepines, e.g. (117) (67AHC(S)2l, p. 43), and 2,4-benzodiazepines, e.g. (118) (68CRV747, p.783). A 5,7-dihydroxy-6fT-dibenzo[[Pg.605]

Azides have been used widely in synthetic approaches to azepines, diazepines, and their annelated derivatives. Two new cyclizations extend the range of azide reactions available. The first of these offers a new route to clavicipitic acid and its analogues (Scheme 6). The key step is a regiospecific intramolecular cycloaddition of the azide group to the neighbouring 24... 

Treatment of 1//-1,2-benzodiazepines (75) with lead tetra-acetate (LTA) gives the previously unknown 5/T-tautomers (76) together with some 3-vinyl-indazoles/ The latter probably derive from the 3//-tautomer (77), as discussed below (refs. 48 and 49). The 5//-1,2-benzodiazepines are less stable than the 3H-and lif-tautomers and can be isomerized to the latter with base they also readily add acetic acid or methanol to give 1,4-adducts. Photolysis of (76) gives 3-acetoxyindole, most likely via (iris + iris) ring-closure of the diazabutadiene unit (cf. 3//-l,2-diazepine and 1//-2,3-benzodiazepines) and extrusion of RCN. 

Many reactions of substituted diazepines and their fused derivatives frequently relate to a study of the functionality rather than being dependent on the presence of the azepine ring system, most particularly with reduced derivatives. Reaction of the unsymmetrical semicarbazones (110) <91JOC5203> gives the two selenodiazoles (111) and (112), the ratios of which show a solvent dependency (Equation (8)). 

The reactions of hexahydro-l,2-diazepine and its Af -ethoxycarbonyl derivative with aryl-isocyanates and arylisothiocyanates have also been reported in the patent literature <84EUPI04484, 93JAP(K)5213970>. Urea derivatives or products of secondary cyclization can be obtained. 

Reviews of interest are listed below general interest <84CHEC-i(7)593, B-89MI906-01 > 2,3-dihydro-diazepinium salts, syntheses, and reactions <93AHC(56)I> 1,4- and 1,5-diazepines and reduced derivatives, syntheses, and reactions 1,4-benzodiazepines spectroscopic aspects, medicinal chemistry, and clinical aspects . 

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