Studies on asymmetric total synthesis of (−)-β-hydrastine via a chiral epoxide ring-opening cascade cyclization strategy

Abstract

Herein, both CF3COOH-catalyzed (86% ee) and KHMDS-catalyzed (78% ee) chiral epoxide ring-opening cascade cyclization to facile and enantioselective synthesis of the core phthalide tetrahydroisoquinoline scaffold of (−)-β-hydrastine are described.

Stereoselective Shi-type epoxidation with 3-oxo-4,6-O-benzylidene pyranoside catalysts: unveiling the role of carbohydrate skeletons

“…[7][8][9][10][11] Small ring heterocycles, such as epoxides, are present in several natural compounds 12,13 and represent highly versatile building blocks, frequently involved in the synthesis of pharmaceuticals and bioactive products. [14][15][16] In addition, carbohydrates possess several hydroxyl groups, which is a unique and valuable characteristic to serve as binding sites, being easily converted to other functional groups based on the structural requirements for catalyst development. In addition, the attachment of bulky groups to these hydroxyl moieties can also be used to block the space around the reactive site of the catalyst, which can control and direct the stereochemistry of the reaction.…”