Diversified Stitching of Ynones with Oxindole-3-oxy acrylates: One-Flask Spiro-annulation Protocol toward Assorted 3H/5H-Spiro[furan-2,3 & PRIME;-indolin]-2 & PRIME;-ones

Spiroannulationof oxindole-3-oxy acrylates with ynones involvingtwo overlapping, base differentiated cascades has been observed. Initialexposure of ynones and oxindole 3-oxy acrylates to K2CO3 triggered a tandem Michael-Michael cascade to delivera pair of spiroannulated diastereomers. Further exposure to LiHMDSled to deep restructuring through a second multistep cascade involvingstereoselective recreation of the C3 quaternary center to furnish3H-spiro[furan-2,3 & PRIME;-indolin]-2 & PRIME;-oneswith functional amplification and scrambling. This new scaffold canbe directly accessed in a one-flask operation from ynones and oxindole-3-oxyacrylates.

Automated summary

Spiroannulation of oxindole-3-oxy acrylates with ynones involving two overlapping, base differentiated cascades has been observed. The initial tandem Michael-Michael cascade delivers a pair of spiroannulated diastereomers, while a second multistep cascade involving stereoselective restructuring leads to the formation of 3H-spiro[furan-2,3'-indolin]-2'-ones with functional amplification and scrambling. This new scaffold can be synthesized in one flask from ynones and oxindole-3-oxy acrylates.