Combination of hydrazine polyanion strategy and ring-closing metathesis in the synthesis of heterocycles

An efficient method for the synthesis of cyclic hydrazine derivatives starting from disubstituted hydrazines is reported. The method is based on the selective alkylation of hydrazine dianions with bromoalkenes and subsequent cyclization using Grubbs' catalysts. The described method provides fast and easy access to the substrates for ring-closing metathesis and the corresponding heterocycles containing a hydrazine moiety. The scope and limitations of the new method are also demonstrated.