Bicyclic intermediates for trichothecane synthesis. Exploitation of an enolate as a protecting group.

✍ Scribed by David J. Goldsmith; Arthur J. Lewis; W.Clark Still Jr.

• Publisher: Elsevier Science
• Year: 1973
• Tongue: French
• Weight: 217 KB
• Volume: 14
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)87342-1

✦ Synopsis

In the course of studies directed towards the total synthesis of trichodermin 1 and trichothecolone 2 we required the a,B-unsaturated Ketones 1 and Q,and the cis-ketol 1 2. We wish to report, first,the preparation of the diketoethers 5 and 1 and their cyclization to give 2 and 4_, respectively. Both the diketo-ethers and the heterocyclic enones are examples of relatively unknown systems. Second, the desired stereoselective introduction of a cis-angularmethyl into diketone 8 can be accomplished using lithium dimethylcuprate(I), and the resulting enolate may then be exploited as a protecting group while methyl lithium is added 1,2 to the saturated carbonyl at C-7. A similar approach