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Yang et al. Chem Synth 2023;3:7 https://dx.doi.org/10.20517/cs.2022.38 Page 13 of 54
Scheme 13. Domino 1,3-dipolar cycloaddition of butyrolactones/valerolactones 27, ninhydrin 28 and proline or thioproline 29. This
figure is used with permission from the Royal Society of Chemistry [54] .
Scheme 14. The biological evaluation. This figure is used with permission from the Royal Society of Chemistry [54] .
spiro chiral centers, with excellent results (up to > 99% yield, > 20:1 dr, and > 99% ee).
The synthetic application of this cascade [3 + 2] cycloaddition was further demonstrated by a diversifying
conversion of 33a into another two functionalized dispirocyclic heterocyclic derivatives 34 and 35 without
damage to the stereocenters [Scheme 16].
Benzolactones as 1C synthons
The great synthetic challenge needs to be addressed for the stereo-controlled synthesis of highly
functionalized polycyclic spirobenzolactone scaffolds, especially for the efficient installation of novel
