Acylhydrazones substitution

A wide variety of /3-lactams are available by these routes because of the range of substituents possible in either the ketene or its equivalent substituted acetic acid derivative. Considerable diversity in imine structure is also possible. In addition to simple Schiff bases, imino esters and thioethers, amidines, cyclic imines and conjugated imines such as cinnamy-lidineaniline have found wide application in the synthesis of functionalized /3-lactams. A-Acylhydrazones can be used, but phenylhydrazones and O-alkyloximes do not give /3-lactams. These /3-lactam forming reactions give both cis and /raMS-azetidin-2-ones some control over stereochemistry can, however, be exercised by choice of reactants and conditions. 

Substituted acylhydrazones (95), formally derivatives of 1,2-diacylhydrazines (75), also cyclize to oxadiazoles (76), with loss of HX. Imidol ethers (95a R2 = H), prepared from acylhydrazines R1CONHNH2 and ortho esters HC(OR)3, cyclize on heating to monosub-stituted oxadiazoles (76 R1 = H). This reaction is an important synthesis of monosubstituted... 

P-Lactams 28 were obtained from reaction of acylhydrazones with chloroacetyl chloride . A -Alkylation of acridine derivatives with 1,3-propane sultone gave 29. P-Phenethylamides gave 3,4-dihydroisoquinolines and N-sulfonyl gave isoquinolines 30. Nucleophilic substitution of 4-bromoisoquinoline gave the corresponding 4-substituted isoquinolines. o-Bromobenzaldehyde was reacted with allylamine and then homophthalic anhydride to afford 31. ... 

A few hydrazides have been treated with ketones and the resulting acylhydrazones XI-127 were reduced to yield substituted hydrazides (XI-128). The properties of these hydrazides are listed in Table XI-33. 

Triazoles have received great synthetic interest in recent years due to their importance as potent pharmacophores." " Different triazole-containing heterocycles exhibit submicromolar activity against LPS-induced tumor necrosis factor-a (TNF-a) and some A-substituted-phenyl-l,2,3-triazole-4-acylhydrazones possess considerable antiplatelet activity on arachidonic acid- and coUagen-induced platelet aggregation." Furthermore,... 

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