Abstract
Alkylation of the 1,4‐diaza‐1,3‐butadiene t‐BuN=CH‐CH=N t‐Bu (t‐BuDAB) by functionally substituted diorganozinc compounds Zn[(CHR^1^XCH~2~)~n~XR^2^]~2~ (n = 1–3, R^1^ = H, Me, XR^2^ = OMe, OBn, SEt, NMe~2~, COOEt) occurs regioselectively. Alkylation occurs at the nitrogen atom of the N=C‐C=N skeleton of t‐BuDAB when primary diorganozinc compounds are used (R^1^ = H), but at the carbon atom when secondary and benzylic diorganozinc compounds are employed. The functional groups in the diorganozinc reagents proved to be important for the alkylation reaction only in the case of Zn[(CH~2~)~3~NMe~2~]~2~ (7) and Zn(C~6~H~4~CH~2~NMe~2−~2)~2~ (16), in which the strongly coordinating NMe~2~ groups give either a decrease of the alkylation rate (7), or no reactivity at all (16). When t‐BuDAB is reacted with Zn[(CH~2~)~2~COOEt]~2~ (10) alone, a 3‐pyrrolidinone (10c) is formed, whereas the same reaction with a mixture of 10 and ClZn(CH~2~)~2~COOEt affords a 2‐pyrrolidinone (10b). The reactions involve a two‐step process involving prior regioselective introduction of the alkyl group either at the N or C atom of an imine unit followed by an intramolecular nucleophilic substitution leading to 10b or 10c, respectively. The molecular structure of 10c shows the functionalized heterocycle to be part of a conjugated enamine system.