This review covers absolute asymmetric syntheses, which allow the preparation of enantiomerically enriched chiral compounds from achiral precursors. By exploiting the crystallization of certain compounds as a conglomerate, enantiopure chiral crystals are spontaneously obtained. These crystals can then be used as reagents, catalysts, or products, enabling the production of chiral compounds with very high enantiomeric excess.

Abstract

This review explores the use of enantiopure chiral crystals as powerful tools for absolute asymmetric synthesis, a field focused on generating enantiomerically enriched products from achiral precursors without chiral reagents or catalysts. We discuss various strategies, including solid-state reactions (solid-gas, solid-grinding, and photochemical reactions) and solution-based approaches utilizing chiral crystals as reagents, catalysts, or products. Key examples include the use of chiral crystals in Strecker reactions, photocycloadditions, and asymmetric catalysis. The review also highlights recent advancements in leveraging chiral conglomerates for spontaneous resolution and enantioenrichment. These methods demonstrate the potential for achieving high enantiomeric excesses and provide insights into the origin of homochirality on Earth.