Organocatalytic formal [3 + 3] cyclization of α-(6-indolyl) propargylic alcohols

Abstract

With the aid of acetic acid, a 1,10-conjugate addition-mediated formal [3+3] cyclization of alkynyl indole imine methides formed in situ from α-(6-indolyl) propargylic alcohols with 1,3-dicarbonyl compounds such as 4-hydroxycoumarins...

Construction of 4-hydroxycoumarin derivatives with adjacent quaternary and tertiary stereocenters via ternary catalysis

“…17 Moreover, formal Friedel-Cras alkylation between 4-hydroxycoumarins and propargylic alcohols has been reported as an efficient way to furnish multisubstituted pyranocoumarins by different research groups. [18][19][20][21] However, approaches toward these scaffolds were limited to using bench-stable reagents and usually under harsh conditions, such as high temperature and microware-mediated conditions. 22 Considering these inherent drawbacks, highly effective synthetic methods with operational simplicity and mild conditions to construct functionalized coumarin derivatives are still highly desired.…”