1,1‐Organoboration of Di‐1‐alkynylsilanes with Alkynyl Groups of Different Reactivity: New Organometallic‐Substituted Siloles

Abstract

Abstract The synthesis of alkynyl[(trimethylstannyl)ethynyl]dimethylsilanes 4 [alkynyl R 1 —C≡C: R 1 = Bu ( b ), t Bu ( c ), i Pent ( d ), Ph ( e ), SiMe 3 ( f )] is reported. The intermolecular 1,1‐ethyloboration of 4 with triethylborane takes place selectively at the Sn—C≡ bond to give first the alkenyl(alkynyl)dimethylsilanes 5 and 6 . There exists an equilibrium between 5 and 6 , and compound 6 has the suitable stereochemistry for the final intramolecular 1,1‐vinyloboration to form the 4‐(diethylboryl)‐2‐(trimethylstannyl)siloles 7 . Protodeborylation of 7 with water gives the 2‐(trimethylstannyl)siloles 8 , and protodeborylation and protodestannylation with an excess of acetylacetone affords the siloles 9 . Multinuclear NMR ( 1 H‐, 11 B‐, 13 C‐, 29 Si‐, and 119 Sn‐) serves for monitoring the reactions and for the characterization of the products.