Recent advances in the efficient synthesis of steroid natural products: emerging methods and strategies

Steroid natural products (SNPs) play an indispensable role in drug discovery owing to their remarkable structural features and biological activities. However, the inadequate amounts of steroid samples derived from natural sources has limited thorough assessment of SNP bioactivities. Accordingly, chemical synthesis of these compounds has become an important, practical way to obtain them in sufficient quantities. Chemists have been focusing on efficient synthesis of SNPs since the 1930s, and significant breakthroughs have been achieved in the past few decades. This review presents advances in this field over the past 20 years, highlighting key C-C bond formation and reorganization reactions in the construction of steroidal skeletons, as well as redox-relay events for the installation of complex oxidation states. We hope this review will serve as a timely reference to allow researchers to quickly learn about state-of-the-art achievements in SNP synthesis and will inspire the development of more powerful strategies for natural product synthesis.