Spacer-bridged ladder compounds—syntheses, structures and synthetic applications

The reaction of α , ω -bis(organodichlorostannyl)alkanes [R(Cl 2 )SnCH 2 ] 2 Z with their corresponding organotin oxides [R(O)SnCH 2 ] 2 Z or ( t -Bu 2 SnO) 3 provides the new spacer-bridged tetraorganodistannoxanes {[R(Cl)SnCH 2 ] 2 Z]O} n ( 22 , Z=CH 2 , R=Me 3 SiCH 2 ; 23 , Z=CH 2 , R=Me 3 CCH 2 ; 24 , Z=CH 2 CH 2 , R=Me 3 SiCH 2 ; 25 , Z=CH 2 CH 2 , R=Me 3 CCH 2 ; 26 , Z=CH 2 CH 2 , R=Me 2 CHCH 2 ; 27 , Z=Me 2 Si, R=Me 3 SiCH 2 ). The acetate substituted derivative 28 {[R(AcO)SnCH 2 ] 2 CH 2 ]O} n (R=Me 3 SiCH 2 ) is obtained by reaction of 22 with silver acetate or by treatment of the organotin oxide [R(O)SnCH 2 ] 2 CH 2 (R=Me 3 SiCH 2 ) with acetic acid. The crystal structures of 23 , 24 , and 28 are described and reveal that these compounds adopt double ladder structures. Depending on the identity of Z and R in chloroform solution the compounds are either dimers ( n =2, 25 – 28 ) or tetramers ( n =4, 22 – 24 ). Also reported are preliminary studies on the catalytic activity in acylation reactions of compounds 22 , 24 – 26 , and 28 .