Catalytic asymmetric Michael/cyclization reaction of 3-isothiocyanato thiobutyrolactone: an approach to the construction of a library of bispiro[pyrazolone-thiobutyrolactone] skeletons

Org Biomol Chem. 2022 Jun 29;20(25):5060-5065. doi: 10.1039/d2ob00773h.

Abstract

Here, we demonstrate the first example of 3-isothiocyanato thiobutyrolactone serving as a useful building block in the Michael/cyclization reaction with alkylidene pyrazolones for the enantioselective construction of optically active structural bispiro[pyrazolone-thiobutyrolactone] skeletons containing three contiguous stereocenters with two spiroquaternary stereocenters. These products were smoothly afforded in up to 90% yield, >20 : 1 dr and >99% ee with chiral squaramide as the catalyst under mild conditions. Notably, this is also the first example of the merger of a spirocyclic pyrazolone scaffold with a spirocyclic thiobutyrolactone scaffold, potentially useful in medicinal chemistry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cyclization
  • Pyrazolones* / chemistry
  • Skeleton
  • Stereoisomerism

Substances

  • Pyrazolones
  • pyrazolone