An alternative general preparation of 2-alkyl-1-benzostannepines and their conversion into 1-benzostibepines and 1-benzoborepines via a tin–metal exchange †

Abstract

The 2-alkyl-1-benzostannepines 4a–g were prepared by the intramolecular hydrostannation of the tin intermediates 3 to an acetylenic moiety in one pot from (Z)-1-(o-bromophenyl)but-1-en-3-ynes 1. The obtained stannepines 4 were easily converted into the 1-benzostibepines 9, 10, 11, 12 and the 1-benzoborepines 14, 15 by tin–antimony and tin–boron exchange reactions in moderate to good yields, respectively. The 1-benzoborepines 14 and 15 are hitherto unknown heterocyclic ring systems.