Concise Synthesis of (-)-isoaltholactone and (±)-5-epi-OBn-Goniotriol

Abstract

Concise route for the synthesis of (-)-isoaltholactone and (±)-5-epi-OBn-Goniotriol were described. Key features for the (-)-isoaltholactone synthesis involved; a) diastereoselective and enantioselective aldol reaction between chiral pyrrolidine substituted γ-benzyloxy vinylogous urethane enolate and cinnamaldehyde afforded highly stereoselective syn δ-lactone, b) allylic 1,3-strain controlled epoxidation of styryl alkene following the stereospecific opening of the epoxide assisted by a proximal benzyloxy group completed the synthesis. Reaction of simple pyrrolidine substituted γ-benzyloxy vinylogous urethane enolate and cinnamaldehyde gave anti δ-lactone. Epoxidation and epoxide opening of the styryl alkene substrate of anti δ-lactone derivative was also investigated, which led to the synthesis of (±)-5-epi-OBn-Goniotriol.

Graphical Abstract

Keywords:

• Isoaltholactone
• aldol reaction
• vinylogous urethane enolate
• δ-lactone

Disclosure statement

The authors declare no conflict of interest.

Supporting information

Full experimental detail,¹H and ¹³C NMR spectra, HPLC traces and X-ray data. This material can be found via the “Supplementary Content” section of this article’s webpage.

Notes

1 e.e. determination, see ESI. p 12.

2 CCDC 2296860 contains the supplementary crystallographic data for 31. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data request/cif

Additional information

Funding

This work was supported by the Ministry of Science and Technology of Taiwan (NSC-100-2113-M-415-001 & NSC-101-2113-M-415-002-MY2) for generous financial support. Partial support of the Mass spectrometer facility provided by National Chung-Hsing University and the X-ray crystallography facility provided by National Taiwan University are acknowledged.