A Chalcogen Bonding Catalysis Platform for Isoprenoid Cyclization: Broad Scope and Diverse Product Frameworks.

Cyclization of isoprenoids is one of the most important biosynthetic events that yields the largest class of natural products. Yet, a noncovalent catalysis strategy for isoprenoid cyclization remains elusive. Furthermore, a general synthetic method using artificial catalyst that enables isoprenoid cyclization with diverse functional groups remains underdeveloped. Herein, we report a noncovalent catalysis strategy for isoprenoid cyclization, and demonstrate that chalcogen bonding with isoprenoids can catalyze a wide range of cyclization reactions. This chalcogen bonding catalysis platform is highlighted by the broad scope since arene, heteroarene, carboxylic acid, alcohol, phenol, enol, sulfamide, ester, and alkyne can participate in the cyclization events, giving diverse classes of products. Moreover, the product frameworks could be varied, affording different ring sizes including seven-membered heterocycles and diverse product structures involving fused-, spiro-, and bridged-ring architectures. As a highlight of this catalysis platform, unusual cyclization reactions between prenyl and alkynes that enable the formation of seven-membered ring and six-membered allene were achieved by chalcogen bonding catalysis while the conventional gold catalysis approach gave different ring systems.