Complete transfer of chirality in an intramolecular, thermal [2 + 2] cycloaddition of allene-ynes to form non-racemic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2011, 7, 601–605, doi:10.3762/bjoc.7.70

• oxindoles into chiral non-racemic spirooxindoles containing an alkylidene cyclobutene moiety. The enantiomeric excesses were determined by chiral lanthanide shift NMR analysis and the transfer of chiral information from the allene to the spirooxindole was found to be greater than 95%. Keywords: alkylidene

• spirooxindoles for application to natural product synthesis [5][6][7]. Herein, we disclose preliminary results demonstrating a complete transfer of chiral information from a chiral non-racemic allene-yne to form an enantiomerically enriched spirooxindole in a [2 + 2] cycloaddition reaction. Findings This study

• , intermolecular [2 + 2] cycloaddition reaction between 2,3-pentadiene and methyl propiolate [10]. In summary, there are only a few general methods to prepare carbocyclic spirooxindoles non-racemically [11][12][13][14]; we have demonstrated the first thermal, intramolecular [2 + 2] cycloaddition reaction of an

A thermally-induced, tandem [3,3]-sigmatropic rearrangement/[2 + 2] cycloaddition approach to carbocyclic spirooxindoles

• Kay M. Brummond and
• Joshua M. Osbourn

Beilstein J. Org. Chem. 2010, 6, No. 33, doi:10.3762/bjoc.6.33

• Kay M. Brummond Joshua M. Osbourn Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, U.S.A 10.3762/bjoc.6.33 Abstract The synthesis of C3-carbocyclic spirooxindoles was realized by way of an intramolecular [2 + 2] cycloaddition reaction between a vinylidene indolin

• Spirooxindoles are structural motifs containing a heterocycle or carbocycle at the C3 position of an oxindole. Particularly well known are the pyrrolidinyl-spirooxindoles 1 which have been classified as a privileged motif due to their presence in a large number of heterocyclic alkaloids (Figure 1) [1

• ]. Spirotryprostatin B (2) is just one example of many natural products from this class exhibiting interesting biological activity [2]. Compounds possessing a carbocycle at the C3 position of the oxindole, such as 3, are less common and spirooxindoles containing a four carbon spirocycle are rare. One notable natural