- Synthesis of δ-tributylstannyl-α,βγ, δ-unsaturated aldehydes from pyridines
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(Equation Presented) Zincke aldehydes, which are readily available from the ring-opening reaction of pyridinium salts, are easily converted into δ-tributylstannyl-α,β,γ,δ-unsaturated aldehydes (stannyldienals) by the action of tributylstannyllithium. This reaction appears to proceed via 1,6-stannyllithium addition/elimination of lithium dialkylamide. Several stannyldienals of significant utility for the synthesis of polyene natural products have been made by this route, which proceeds in modest yields, but is successful on multigram scale using inexpensive reagents. Simple stannylenals and stannylenones are similarly available from the corresponding vinylogous amides.
- Michels, Theo D.,Rhee, Jong Uk,Vanderwal, Christopher D.
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supporting information; experimental part
p. 4787 - 4790
(2009/05/07)
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- Stereocontrolled synthesis of Z-dienes via an unexpected pericyclic cascade rearrangement of 5-amino-2,4-pentadienals
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Donor-acceptor dienes known as Zincke aldehydes, which derive readily from the ring-opening reactions of pyridinium salts with secondary amines, undergo a fascinating thermal rearrangement reaction to afford Z-α,β,γ,δ-unsaturated amides with excellent stereoselectivity. Efficient, stereocontrolled access to Z-trisubstituted alkenes with two different substitution patterns is possible in three steps beginning with the appropriately substituted pyridine derivative. Preliminary studies have shown that both the amide and the monosubstituted alkene termini can be selectively functionalized. Ease of access, generality of scope, and facile product manipulation render this process attractive for the synthesis of complex polyenes. Copyright
- Steinhardt, Sarah E.,Silverston, Joel S.,Vanderwal, Christopher D.
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p. 7560 - 7561
(2008/12/22)
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