Convergent synthesis and characterization of organotin dendrimers Sn{(CH2)nSn[(CH2)4SnPh3]3}4 (n = 3, 4)

The reaction of the ω-haloalkyltin trihalides Br(CH 2 ) 3 SnBr 3 and Br(CH 2 ) 4 SnBr 3 with 3 equiv of but-3-enylmagnesium bromide yielded Br(CH 2 ) 3 Sn(CH 2 CH 2 CH=CH 2 ) 3 (3) and Br(CH 2 ) 4 Sn(CH 2 CH 2 -CH=CH 2 ) 3 (4). Both dendritic branches can be converted into their corresponding Grignard reagents, whose consequent treatment with 0.25 M amounts of SnCl 4 resulted in the formation of the dendrimers Sn[(CH 2 ) 3 Sn(CH 2 CH 2 CH=CH 2 ) 3 ] 4 (5) and Sn[(CH 2 ) 4 Sn(CH 2 CH 2 CH=CH 2 ) 3 ] 4 (6), respectively. The subsequent hydrostannation of 5 and 6 delivered Sn{(CH2)3Sn[(CH2)4SnPh3]3}4 (7) and Sn{(CH 2 ) 4 Sn[(CH 2 ) 4 SnPh 3 ] 3 } 4 (8) as dendrimers of the second generation. All compounds were characterized by elemental analysis, 1 H, 13 C, and 119 Sn NMR spectroscopy, and MALDI-TOF mass spectrometry.