Abstract
The bifunctional quinine-catalyzed stepwise (3+2) cycloaddition for the enantioselective construction of spirooxindole-fused cyclopenta[c]chromen-4-ones is developed. The reactions of 3-homoacylcoumarins and alkylidene oxindole electrophiles generate aforementioned spirooxindole-chromenone adducts bearing five contiguous stereocenters, of which one is the spiro all-carbon quaternary stereocenter in high yields (up to 99%) with excellent stereoselectivities (up to >20:1 dr and 99% ee). This methodology was investigated for three different alkylidene oxindole electrophiles and could also be practically demonstrated on a gram scale. Mechanistic investigations revealed that the (3+2) cycloaddition for the enantioselective synthesis of spirooxindole-fused cyclopenta[c]chromen-4-ones is proceeding via a stepwise reaction pathway. (Figure presented.).
Original language | English |
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Pages (from-to) | 1679-1685 |
Number of pages | 7 |
Journal | Advanced Synthesis and Catalysis |
Volume | 362 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2020 Apr 17 |
Keywords
- 3-homoacylcoumarins
- cyclopenta[c]chromen-4-ones
- organic catalysis
- spiro compounds
- stepwise (3+2) cycloaddition
ASJC Scopus subject areas
- Catalysis
- Organic Chemistry