1,1-allylboration of bis(silyl)ethynes: electron-deficient SiHB bridges and novel heterocycles via intramolecular hydrosilylation

The reaction of bis(silyl)ethynes 2–4, bearing one, two and three hydrides at one of the silicon atoms, with triallylborane 1 leads primarily to alkenes 5, 8 and 11 respectively by 1,1‐allylboration. In these alkenes, the diallylboryl and the silyl group bearing one or more SiH functions are in cis...

Full description

Saved in:
Bibliographic Details
Published in:Applied organometallic chemistry 2004-01, Vol.18 (1), p.43-50
Main Authors: Wrackmeyer, Bernd, Tok, Oleg L., Bubnov, Yuri N.
Format: Article
Language:English
Subjects:
allylboration
boranes
heterocycles
hydrosilylation
NMR
silanes
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The reaction of bis(silyl)ethynes 2–4, bearing one, two and three hydrides at one of the silicon atoms, with triallylborane 1 leads primarily to alkenes 5, 8 and 11 respectively by 1,1‐allylboration. In these alkenes, the diallylboryl and the silyl group bearing one or more SiH functions are in cis‐positions at the CC bond, giving rise to the formation of an electron‐deficient SiHB bridge. This follows unambiguously from the consistent set of NMR data, in particular from the observation of isotope‐induced chemical shifts 2Δ10/11B(29Si). The activation of the SiH bond in 5, 8 and 11 induces intramolecular hydrosilylation under very mild reaction conditions to give 1,4‐silabora‐cyclo‐2‐heptenes 7, 10 and 13 respectively. Upon heating, these seven‐membered heterocycles undergo ring contraction by 1,1‐deallylboration to give the 1‐sila‐cyclo‐2‐hexenes 14–16, and bear an exocyclic diallylboryl group in 3‐position. All proposed structures are based on consistent 1H, 11B, 13C and 29SiNMR data. Copyright © 2004 John Wiley & Sons, Ltd.
ISSN:0268-2605
1099-0739
DOI:10.1002/aoc.555