Neue bororganische Ringe mit benachbarten Bor‐Atomen Katalysierte 1,2‐Diborierung von Alkinen

New Organoboron Rings with Neighboring Boron Atoms. Catalyzed 1,2‐Diboration of Alkynes The new 1,2‐diamino‐1,2‐diboracycloalkanes (CH 2 ) n (BNEt 2 ) 2 3 ( n = 3) and 4 ( n = 4) are prepared from the corresponding 1,ω‐bis(dichloroboryl)alkanes in a two‐step synthesis. The ring compounds 3 and 4 react with alkynes under the catalytic action of Et 2 O–BF 3 to produce the new 1,4‐dibora‐2‐cycloalkenes (CH 2 ) n (BNEt 2 ) 2 (CR=CR') 5 ( n = 3,4 and R,R' = e.g. H, Me, Et).