posted on 2023-11-27, 18:08authored bySagar
S. Thorat, Sagar P. Shimpi, Pooja I. Sambherao, Gamidi Rama Krishna, Ravindar Kontham
Spiroketals and oxaspirolactones are widely found in
biologically
active natural products, serving as important structural motifs. In
this study, we present a Cu(II)-catalyzed cascade cycloisomerization
of 2-(5-hydroxyalkynyl)benzoates, enabling the regioselective synthesis
of benzannulated [5,6]-oxaspirolactones containing an isochromen-1-one
moiety. This strategy offers a rapid and efficient approach to access
a diverse array of benzannulated [5,6]-oxaspirolactones. The methodology
presented here showcases a broad substrate scope, delivering good
yields and scalability up to gram scale. The structures of the oxaspirolactones
were unequivocally confirmed through single-crystal X-ray analysis
and by analogy using 1H and 13C{1H} NMR data.