Synlett 2009(11): 1713-1729  
DOI: 10.1055/s-0029-1217352
ACCOUNT
© Georg Thieme Verlag Stuttgart ˙ New York

Strategies for the Synthesis of the Cyclopropyl-Substituted Lactone Family of Oxylipins

James D. White*a, Jongtae Yangb
a Department of Chemisty, Oregon State University, Corvallis, Oregon 97331-4003, USA
e-Mail: james.white@oregonstate.edu;
b College of Pharmacy, Oregon State University, Corvallis, Oregon 97331, USA
Further Information

Publication History

Received 19 December 2008
Publication Date:
12 June 2009 (online)

Abstract

Biomimetic and other strategies that have been developed in the author’s laboratory for the synthesis of a subset of the group of enzymically oxidized lipids known as oxylipins are described. This set of oxylipins contains both a cyclopropane and a lactone, with the lactone ring size varying between six and nine members. A biomimetic approach employing cascade cyclization of an epoxyalkenoic acid was successful in creating the cyclopropane and six-membered lactone of C20 oxylipins such as the constanolactones in a single step, but failed in an attempt to create the nine-membered lactone of halicholactone. Solandelactones, C22 oxylipins containing a cyclopropane and an eight-membered lactone, were synthesized by directed Simmons-Smith cyclopropanation followed by Claisen rearrangement of a cyclic ketene acetal to construct the lactone

1 Introduction

2 The First Biomimetic Cascade Synthesis of an Oxylipin

3 Biomimetic Cascade Synthesis of Constanolactones A and B

4 A Failed Biomimetic Strategy for Halicholactone

5 Synthesis of the C22 Oxylipins Solandelactones A, B, E, and F

5.1 A Ring-Closing Metathesis Approach to the Octenalactone Portion of Solandelactones

5.2 The Petasis-Claisen Rearrangement Route to the Octenalactone Portion of Solandelactones

6 Conclusion

51

An ab initio calculation using a Hartree-Fock/6-31G** basis set places the barrier at 7-9 kcal˙mol