An on-water [4 + 2] annulation reaction between 2-methyl-3H-indolium salt and α-bromo N-acyl hydrazone has been developed. The environmentally friendly strategy provides the first facile access to spiro(indoline-2,3'-hydropyridazine) scaffolds.
An efficient formal (3 + 1 + 1) carboannulation
strategy of Morita–Baylis–Hillman
(MBH) carbonates with pyridinium ylides was developed for constructing
diversely functionalized spiro-cyclopentadiene oxindoles. The reaction
initiates with an SN2′ olefination of MBH carbonates
with pyridinium ylides. The in situ generated dienes
then engage in a challenging (4 + 1) ylide carboannulation, which
has been rarely reported before. The reaction features broad substrate
scope as well as high chemo- and regioselectivity. (3 + 1 + 1) carboannulation
products could be easily transformed into interesting spiro-cyclopenta[c]furan oxindoles.
An efficient one-pot, two-step, three-component reaction of isatin-derived MBH carbonates, sulfilimines, and epoxides was achieved, thus affording pharmaceutically important spiro-oxindole dihydropyridines.
A silver-catalyzed one-pot cycloisomerization/[2 + 3] cycloaddition of enynamides with in situ generated nitrile imines has been developed. Unlike the well-established cycloisomerization/[4 + n] cycloadditions of enynamides, this strategy provides efficient access to a new type of spiropyrazolines, which exhibit an anti-proliferation effect on multiple tumor cell lines. The compound 3u exhibits obvious anticancer activity by inducing apoptosis in RKO cells. The combination of compound 3u and an autophagy inhibitor could improve its anti-proliferation capacities.
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