Rh(iii)-catalyzed sequential spiroannulation/lactonization of 3-aryl N-sulfonyl ketimines with 4-hydroxy-2-alkynoates by C–H bond activation†
B.
Sridhar 
b
and
B. V. Subba
Reddy
*ac
b
and
B. V. Subba
Reddy
*ac
Abstract
A sequential rhodium(III)-catalyzed spiroannulation and lactonization strategy has been developed for the synthesis of a highly rigid spirobenzosultam lactones in good yields with high regioselectivity by means of aromatic ortho-C–H bond activation/functionalization of 3-aryl N-sulfonyl ketimines with 4-hydroxy-2-alkynoates. The reaction proceeds through a cascade of C–H activation followed by spiroannulation and lactonization. In this approach, two C–C and C–O bonds are formed in a single step. This is the first report on the spiroannulation of cyclic N-sulfonyl ketimines with hydroxyalkynoates.
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