Adventures and Detours in the Synthesis of Hydropentalenes

◊ These coauthors contributed equally to this work.

Abstract

Functionalized hydropentalenes (i.e., bicyclo[3.3.0]octanones) constitute important building blocks for natural products and for ligands for asymmetric catalysis. The assembly and tailored functionalization of this convex roof-shaped scaffold is challenging and has motivated a variety of synthetic approaches including our own contributions, which will be presented in this account.

1 Introduction

2 Biosynthesis of Hydropentalenes

3 Hydropentalenes through the Pauson–Khand Reaction

4 Hydropentalenes through Transannular Oxidative Cyclization of Cycloocta-1,4-diene

5 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Dodecahydrocyclopenta[a]indenes

6 Functionalization of Bicyclo[3.3.0]octan-1,4-diones to Crown Ether Hybrids

7 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Cylindramide

8 Tandem Ring-Opening Metathesis/Ring-Closing Metathesis/Cross-Metathesis of Bicyclo[2.2.1]heptanes

9 Functionalization of Bicyclo[3.3.0]octan-1,4-dione to Geodin A

10 Hydropentalenes through Enantioselective Desymmetrization of Weiss Diketones

11 Functionalization of Weiss Diketones by Carbonyl Ene Reactions

12 Functionalization of the Weiss Diketone to Cylindramide and Geodin A Core Units

13 Biological Properties of Bicyclo[3.3.0]octanes

14 Hydropentalenes through Vinylcyclopropane Cyclopentene Rearrangement

15 Functionalization of Bicyclo[3.3.0]octanes toward Chiral Dienes

16 Miscellaneous Syntheses of Hydropentalenes

17 Conclusion and Outlook

Key words

bicyclooctanes - diene ligands - hydropentalenes - natural product synthesis

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