Heterocyclic Steroids

Steroids are organic compounds with four rings arranged in a precise molecular configuration and are involved in many biological functions displaying a wide spectrum of biological activities and diverse chemical reactivities. Structural modifications of the steroidal rings have attracted a considerable amount of attention recently. Steroids of natural origin have been modified in several ways, particularly in the cyclopentanophenanthrene ring system with heteroatoms such as nitrogen, oxygen, and/or sulfur or with the heterocyclic ring to obtain more active compounds with less or no harmful side effects and are termed as heterosteroids or heterocyclic steroids. Heterocyclic steroids are enticing as the minor modifications to the steroidal molecules, produce remarkable differences in their biological activities. The introduction of the heteroatom in the skeleton of a steroidal molecule often poses challenges to organic chemists, demanding the exploration of new synthetic reactions and new synthetic routes. In this article, the overview of the various synthetic strategies employed to synthesize azasteroids, oxasteroids, thiasteroids, and steroids modified by the introduction of the heterocyclic ring is broadly covered along with its biological significance.