A copper(ii) perchlorate-promoted tandem reaction of internal alkynol and salicyl N-tosylhydrazone provides a novel, concise method for constructing isochromeno[3,4-b]chromene in 35-94% yields. The tandem reaction involves cycloisomerization, formal [4+2] cycloaddition and an elimination process.
A novel Lewis acid catalyzed tandem cyclization reaction of internal alkynols and vinyl azides has been achieved to afford a series of products containing a pyran-based indeno[1,2-c]isochromene scaffold in moderate to high yields. This tandem polycyclization protocol provides a straightforward entry to construct the complex polycyclic skeleton through cycloisomerization, formal [4 + 2] cycloaddition, and an elimination process.
Isochromene derivatives are important structural motifs found in various biologically activec ompounds as well as important natural products. Am ethod to generate CF 3 -containing isochromene derivatives has been developed, which gives moderate to good yields by using To gni's reagent as the trifluoromethyl source. The key step involves alkynol cyclization and subsequent trapping by ar eactive electrophilic trifluoromethyl species generated in situ from To gni's reagent.
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