Page 83 - Read Online
P. 83
Yang et al. Chem Synth 2023;3:7 https://dx.doi.org/10.20517/cs.2022.38 Page 47 of 54
Scheme 62. Spirolactonization reaction of isatins 106 and α, β-unsaturated aldehydes 125. This figure is used with permission from the
[137]
Royal Society of Chemistry .
Scheme 63. Total synthesis of maremycin B. This figure is used with permission from the Royal Society of Chemistry [137] .
scaffolds are mainly limited to spirobutyrolactones and spirovalerolactones derivatives. At the time of this
writing, there are no other cascade reactions available for the catalytic asymmetric construction of chiral
spiropropyllactones. So, the careful design of specific reagents to develop an efficient and versatile platform
for organocatalytic asymmetric cascade synthesis is highly desired. (b) Although spirolactone moiety exists
in lots of natural products, the successful application of organocatalytic asymmetric cascade reactions in the
total synthesis of natural products is still limited. (c) Although controlling the enantioselectivity in catalytic
asymmetric radical reactions remains a great challenge, it is highly valuable to have new activation models
for the synthesis of spirolactones by the combination of asymmetric organocatalysis with visible light
photoredox and electrochemical synthesis. (d) The biological properties of spirolactone derivatives need to
