A-Nitrosopiperazines and Related Compounds

There are several preparative routes to A-nitrosopiperazines, illustrated by the following examples  

Note The mechanism of such nitrosations has been studied.  

Piperazine (25) gave 1-nitrosopiperazine (26) [substrate, (KSO3)2NO, Na2CO3, H2O—pyridine H2NOH.HCI J, 20°C, 15 min 98% the mechanism appears to involve the unisolated complex (24)] ° - 

Note Although such a procedure was successful in related series, 4-methyl- 

1-piperazinamine (27) failed to give l-methyl-4-nitrosopiperazine (28) on treatment with tri-tert-butylamine oxide in tetranitromethane. 

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