Cyclic amidines

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. 

Monoamines, primary diamines and secondary amines react with nitriles to give amidines, cyclic amidines and pyrimidines, respectively, in the presence of Yb(OTF)3 as a catalyst. Reaction of ammonia with acetonitrile is shown below. 

Amidines, cyclic Triethyl orthoformate. o-Aminoketones Sodium methoxide. 

Mannich bases, transamination with amidines, cyclic 18, 482 suppl. 21 Mannich reaction —, N-heterocyclics by — 21, 798 —, double, N-heterocycles by — 13, 775 suppl. 21 anfi-Markownikoff hydro-halogenation 14, 205 suppl. 21... 

Phenylacetylene has been converted to an ynamine by reaction with dimethylamine and Cu(OAc)2 in a stream of 02 Ynamines react with a variety of reagents to form pyrrocolines, 2- and 4-quinolones, unsaturated amidines, cyclic sulfones, and 4-membered cyclic enol ethers53. 

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