Reactions of Al‐N Based Active Lewis Pairs with Ketones and 1,2‐Diketones: Insertion into Al‐N Bonds, C‐C and C‐N Bond Formation and a Tricyclic Saturated Tetraaza Compound

The monomeric aluminum hydrazide i Bu 2 Al‐N(C 10 H 15 )(NC 5 H 10 ) ( 1 ) features a strained AlN 2 ring and is an efficient active Lewis pair. It reacted with 2,3‐diphenyl‐2‐cyclopropen‐1‐one by insertion of the C=O group into an Al‐N bond, cleavage of the C 3 ring and formation of an AlOC 3 heterocycle ( 2 ). Diacetyl, Me(O)C–C(O)Me, and 1 afforded by insertion of keto groups into both Al‐N bonds a heterocyclic α‐keto‐hemihydrazinal coordinated to aluminum ( 3 ). 3 contains fused AlO 2 C 2 and C 2 N 2 heterocycles. In an unexpected reaction, benzil, PhC(O)‐C(O)Ph, afforded by C–C and C–N bond formation a unique tricyclic dimer ( 4 ) of the hydrazone H 10 C 5 N–N=C 10 H 14 , which is the starting material for the synthesis of 1 . This reaction may involve a radical process, and benzil radical anions coordinated to Al were detected as by‐products. In contrast, 1 reacted with simple ketones to yield alcoholates [ i Bu 2 AlOR] 2 [R = OC(H)(Ph)‐C≡C‐Ph ( 5 ), OCHPh 2 ( 6 )] by retrohydroalumination and reaction of resulting i Bu 2 Al‐H with C=O groups.