Reactions of N-Monosubstituted Amidines with AlMe<sub>3</sub> and AlMeCl<sub>2</sub>: Formation of Fused Triazaalane Heterocycles
作者:K. Maheswari、N. Dastagiri Reddy
DOI:10.1021/om2007375
日期:2012.1.9
Reactions of N-monosubstituted amidines of the formula HN=C(R) NH(R') (R = Ph, 4-tert-butylphenyl, Me; R' = 2,6-dlisopropylphenyl, Ph) with AlMe3 and AlMeCl2 are reported. All the N-(Dipp)amidines (Dipp = 2,6-diisopropylphenyl) react with AlMe3 in a 1:1 ratio to yield tetrameric aluminum amidinates (1, 2, and 3) in good yields. In these compounds, the amidinate ligand chelates to Al while bridging to another Al. However, when N-phenylamidines are employed, tetracyclic (4-9) and pentacyclic (10) Al-N-C heterocycles are formed. In the case of N-phenylbenzamidine, formation of a hexacyclic Al-N-C heterocycle (11) is observed when a slight excess of AlMe3 (1:1.2 equiv) is used. In these compounds, the amidinate ligand coordinates to Al atoms in a bridging fashion, Further, N-(Dipp)acetamidine and N-(Dipp)benzamidine are also treated with AlMeCl2. Whereas N-(Dipp)acetamidine affords an ionic 15-membered aluminum amidinate chain (12), N-(Dipp)benzamidine gives a bicyclic heterocycle (13) and the AlCl3 adduct of N-(Dipp)benzamidine (14). However, from a reaction between N-phenylbenzamidine and AlMeCl2, only the AlC13 adduct, 15, was isolated. Compounds 3, 4, 6, 8, and 10-15 have been structurally characterized.