Synthesis and Discovery of Estra-1,3,5(10),6,8-pentaene-2,16α-diol

An Estrogen Receptor β Agonist with AR Antagonist Activity from a Modern Asymmetric De Novo Steroid Synthesis

While the androgen receptor (AR) has long been a molecular target of prostate cancer therapeutics, the estrogen receptor β (ERβ) has more recently become of interest in this area of chemotherapeutic space due to its demonstrated role as a tumor suppressor. Here, we report studies that build on our earlier discovery of an exquisitely potent and selective steroidal agonist of ERβ that have resulted in the identification of a synthetic substituted estrane that, in reporter assays, is a potent and selective agonist of ERβ over ERα while also possessing activity as an antagonist of the AR that has potency within 7-fold of enzalutamide. Notably, this discovery was made possible by leveraging the power of our modern asymmetric de novo chemical synthesis of estranes that obviates the typical dependence on semisynthesis (natural product derivatization) for steroid-based medicinal chemistry.

Toward the Asymmetric de Novo Synthesis of Lanostanes: Construction of 7,11-Dideoxy-Δ5-lucidadone H

Efforts to establish an asymmetric entry to hexanorlanostanes has resulted in a concise synthesis of 7,11-dideoxy-Δ5-lucidadone H from epichlorohydrin. By exploiting metallacycle-mediated annulative cross-coupling (to establish a functionalized hydrindane) and stereoselective formation of the steroidal C9-C10 bond to establish a stereodefined 9-alkyl estrane, 14 subsequent steps have been established to generate a hexanorlanostane system. Key transformations include formal inversion of the C13 quaternary center, oxidative dearomatization/group-selective Wagner-Meerwein rearrangement, and Lewis acid mediated semi-Pinacol rearrangement.

Progress toward the De Novo Asymmetric Synthesis of Euphanes

Progress toward an asymmetric synthesis of euphanes is described. A C14-desmethyl euphane system possessing five differentially substituted and electronically distinct alkenes has been prepared. The route employed is based on sequential metallacycle-mediated annulative cross-coupling, double asymmetric Brønsted acid mediated intramolecular Friedel-Crafts alkylation, and an oxidative rearrangement to establish the requisite C10 quaternary center. These studies have also led to the discovery of a novel euphane-based modulator of the Liver X Receptor.

From an ent-Estrane, through a nat-Androstane, to the Total Synthesis of the Marine-Derived Δ8,9-Pregnene (+)-03219A

The total synthesis of (+)-03219A, a rare Δ^8,9-pregnene isolated from the marine-derived Streptomyces sp. SCSIO 03219, is described that is based on a series of transformations that enable progression from epichlorohydrin to an ent-estrane, then conversion to a nat-androstane, and finally establishment of the natural product target. Key to the success of these studies was implementation of two rearrangement processes to formally invert the quaternary center at C13 and establish the C10 quaternary center.

Recent Progress in Steroid Synthesis Triggered by the Emergence of New Catalytic Methods

The rich biology associated with steroids dictates a growing demand for the new synthetic strategies that would improve the access to natural and unnatural representatives of this family. The recent advances in the field of catalysis have greatly impacted the field of natural product synthesis including the synthesis of steroids. This article provides a short overview of the recent progress in the synthesis of steroids that was enabled by the advances in catalysis.