Download PDF
Synfacts 2008(9): 0945-0945  
DOI: 10.1055/s-2008-1078636
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Stereocontrolled Thermal Pericyclic Cascade Rearrangement

Contributor(s):Mark Lautens, Praew Thansandote
S. E. Steinhardt, J. S. Silverston, C. D. Vanderwal*
University of California at Irvine, USA
Stereocontrolled Synthesis of Z-Dienes via an Unexpected Pericyclic Cascade Rearrangement of 5-Amino-2,4-pentadienals
J. Am. Chem. Soc.  2008,  130:  7560-7561  
CrossrefPubMed
Further Information

Publication History

Publication Date:
22 August 2008 (online)

 PDF Download Permissions and Reprints

Key words

pericyclic rearrangement - Z-α,β,δ,γ-unsaturated amides - Zincke aldehydes

Significance

While attempting a proposed step in an alkaloid total synthesis, the authors discovered a novel pericyclic cascade involving two 6p-electrocyclization-ring-opening reactions and a [1,5]-hydrogen shift. Various 5-amino-2,4-pentadienals (or Zincke aldehydes) rearranged in this manner to form Z-a,b,g,d-unsaturated amides in moderate to good yields and good diastereoselectivities. The products can be manipulated to convert into alcohols or undergo cross-metathesis with other alkenes.

Comment

The mechanism is thought to involve a nitrogen transposition from one end of the carbon chain to the other and not an oxygen transposition in the same manner. Preliminary studies indicate that small amounts of camphorsulfonic acid increase the reaction rates, which may help to lower the high reaction temperatures required for the rearrangement.

   Permissions and Reprints