Hydrostannylation of Propargylic Alcohols Using Mixed Tin Hydrides

The hydrostannylation of a series of alkynols and propargylic ethers with mixed tin hydrides Bu2SnHCl and Bu2SnHBr has been studied. These highly reactive tin hydrides undergo radical chain reactions at low to ambient temperatures (−78 °C to 25 °C). Their higher Lewis acidity (in comparison with the...

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Bibliographic Details
Published in:European journal of organic chemistry 2004-01, Vol.2004 (2), p.337-353
Main Authors: Thiele, Christina M., Mitchell, Terence N.
Format: Article
Language:English
Subjects:
Alcohols
C−C coupling
Hydrides
Regioselectivity
Tin
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Summary:The hydrostannylation of a series of alkynols and propargylic ethers with mixed tin hydrides Bu2SnHCl and Bu2SnHBr has been studied. These highly reactive tin hydrides undergo radical chain reactions at low to ambient temperatures (−78 °C to 25 °C). Their higher Lewis acidity (in comparison with the most commonly used hydrostannylation reagent Bu3SnH) leads to much better regio‐ and stereoselectivities irrespective of the size and nature of the substituents in the propargylic position. Hydrostannylation of terminal propargylic alcohols and ethers gives almost solely (> 90 %) the products of anti‐addition; these are stabilized by intramolecular coordination. When non‐terminal propargylic alcohols are used, the isomerisation to the thermodynamically favoured syn‐addition product, which normally takes place in free radical hydrostannylations, can be prevented by choosing appropriate reaction conditions. Hydrostannylation of allyl propargyl ether shows that these reagents are highly chemoselective towards C−C triple bonds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
ISSN:1434-193X
1099-0690
DOI:10.1002/ejoc.200300489