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Synthesis and Characterization of Spirosilanes – 1,2‐Hydroboration and 1,1‐Carboboration
Author(s) -
Khan Ezzat,
Wrackmeyer Bernd,
Döring Cristian,
Kempe Rhett
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402286
Subject(s) - hydroboration , chemistry , silanes , boranes , intramolecular force , borane , silane , nuclear magnetic resonance spectroscopy , acetic acid , stereochemistry , medicinal chemistry , boron , organic chemistry , catalysis
Starting from dichloro(divinyl)silane, the dialkynyl(divinyl)silanes (CH 2 =CH) 2 Si(C≡CR) 2 (R = t Bu, p ‐tolyl, 3‐thienyl, CH 2 NMe 2 ) were prepared. These silanes were treated with 9‐borabicyclo[3.3.1]nonane (9‐BBN) for 1,2‐hydroboration of the vinyl groups. The hydroboration products rearranged quickly and quantitatively by intramolecular 1,1‐carboboration into the respective target compounds, the axially chiral 5‐silaspiro[4.4]nona‐1,6‐dienes bearing boryl groups at the 2‐ and 7‐positions and the R substituents at the 1‐ and 6‐positions. Simple protodeborylation with acetic acid proved possible, except for R = t Bu. The remaining Si–C function in (CH 2 =CH) 2 Si(Cl)C≡C t Bu opens the way to new spirosilanes after a sequence of hydroboration/carboboration/hydroboration, for which a first example was studied. The products were characterized by X‐ray diffraction in the solid state and NMR spectroscopy in solution ( 1 H, 11 B, 13 C, 15 N, 29 Si), complemented by optimization of gas‐phase structures and calculation of NMR parameters by DFT methods.