Zinc-Mediated C‑3 α‑Prenylation of Isatins with Prenyl Bromide: Access to 3‑Prenyl-3-hydroxy-2-oxindoles and Its Application

A convenient
and highly α-regioselective strategy for the
synthesis of 3-prenyl-3-hydroxy-2-oxindoles has been developed starting
from isatins and prenylzinc with good to excellent yields. This protocol
provides a straightforward and practical way to introduce an α-prenyl
moiety into the C-3 position of isatins. The advantages of this reaction
are use of the cheap and readily available reagents, operational simplicity,
and wide substrate scope. Furthermore, this transformation was applied
to the synthesis of several oxindole-containing natural products,
which further demonstrated the synthetic utility of this methodology.