Terminally Dimetallated N , N′ ‐Dimethylpiperazines with Doubly Spirocyclic Structures

Dilithiated N,N′ ‐dimethyl‐piperazine, LiCH 2 N(CH 2 CH 2 ) 2 NCH 2 Li ( 2 ) was prepared by transmetallation of N,N′ ‐bis(trimethylstannylmethyl)‐piperazine ( 1 ) with n BuLi and was isolated as a highly pyrophoric yellowish powder in high yield. Compound 2 was characterized by elemental analysis and was reacted as difunctional aminomethylating reagent with dialkyl‐earth metal chlorides, R 2 MCl (M = Al, Ga; R = Me, t Bu) which resulted in the formation of spirocyclic adducts of N,N′ ‐bis(dialkylmetallamethyl)‐piperazine and unreacted dialkylmetal chlorides, [(Me 2 AlCl)Me 2 AlCH 2 N(CH 2 CH 2 ) 2 NCH 2 AlMe 2 (ClAlMe 2 )] ( 3 ) and [( t Bu 2 GaCl) t Bu 2 GaCH 2 N(CH 2 CH 2 ) 2 NCH 2 Ga t Bu 2 (ClGa t Bu 2 )] ( 4 ) with five‐membered rings. Compounds 1 , 3 and 4 were identified by NMR‐spectroscopy ( 1 H, 13 C, 119 Sn for 1 , 27 Al for 3 ), mass spectra (EI, for 1 ) and by crystal structure determinations.