The Diels-Alder Reaction in Steroid Synthesis

This review explores the myriad ways in which the Diels–Alder­ reaction has been employed in the construction of the tetracyclic steroid nucleus. A systematic analysis of possible approaches highlights both the synthetic versatility of this ubiquitous reaction and also opportunities for new routes to fused tetracarbocyclic steroid frameworks. 1.1 Introduction 1.2 Classification of the Approaches 2.1 Installation of a Non-Skeletal Ring 2.2 Construction of the A-Ring 2.3 Construction of the B-Ring 2.4 Construction of the C-Ring 2.5 Double Diels–Alder Sequences 3 Conclusions and Future Prospects