Silicon-guided rearrangement of 10-methyl-4,5-epoxydecalins. Methyl versus methylene migration

Blay, Gonzalo; Cardona, Luz; Collado, Ana M.; Garcı́a, Begoña; Pedro, José R.

doi:10.1016/j.tetlet.2003.09.023

Cited by 6 publications

(5 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hydrogenolysis of the C-Se bond using Raney Ni gave alkene 34 in 87% yield. Finally, epoxidation of 34 with MMPP gave epoxide 35 as the only product [16]. These results showed that a TMS group on C-1 or C-9 promoted the acidic rearrangement of 10-methyl-4,5-epoxy decalins with exclusive migration of the methyl or methylene groups linked directly to C-10.…”

Section: Methodsmentioning

confidence: 85%

See 1 more Smart Citation

Synthesis of Sesquiterpenes via Silicon-Guided Rearrangement of Epoxydecalins

Blay

Collado

Garcı́a

et al. 2008

Natural Product Communications

Self Cite

View full text Add to dashboard Cite

A survey of the rearrangement of methyldecalins via C-5 carbocation intermediates, with special attention to the silicon-guided rearrangement of epoxydecalins is provided. A TMS group properly positioned on either C-1 or C-9 promotes the acidic rearrangement of 10-methyl-4,5-epoxydecalins and 10-methyl-5,6-epoxydecalins with exclusive migration toward C-5 of the methyl or methylene groups linked directly to C-10. The application of this biomimetic approach to the synthesis of a number of spirocyclic and eremophilane sesquiterpenes is reported.

show abstract

Section: Methodsmentioning

confidence: 85%

“…Hydrogenolysis of the C-Se bond using Raney Ni gave alkene 34 in 87% yield. Finally, epoxidation of 34 with MMPP gave epoxide 35 as the only product [16].…”

Section: Methodsmentioning

confidence: 99%

Synthesis of Sesquiterpenes via Silicon-Guided Rearrangement of Epoxydecalins

Blay

Collado

Garcı́a

et al. 2008

Natural Product Communications

Self Cite

View full text Add to dashboard Cite

show abstract

“…Three main concerns may be encountered during the acid-catalyzed rearrangement of this kind of epoxides: (a) lack of selectivity of the migrating group, (b) 1,2-elimination of the hydroxyl group before rearrangement, and (c) a Grob-type rearrangement of the 1,3-hydroxycarbocations that result after the initial rearrangement in the case of epoxides. , In previous work, we have shown that some of these problems can be overcome and selectivity during migration can be gained by introducing a TMS group in the vicinity of the migrating group. In the case of simple decalines, we found that methylene migration was preferred if the epoxide and the TMS group were on the same ring, while methyl migration was the main pathway if both groups were on different rings of the decalin system .…”

Section: Introductionmentioning

confidence: 88%

Rearrangement of 4,5-Epoxy-9-trimethylsilyldecalines. Application to the Synthesis of the Natural Eremophilane (−)-Aristolochene

et al. 2006

Self Cite

View full text Add to dashboard Cite

Several 4,5-epoxy-9-trimethylsilyl-eudesmanes and 15-nor-eudesmanes, having different relative stereochemistry and substitution at the oxirane ring, have been prepared starting from (-)-carvone and subjected to acid-promoted rearrangement. The presence of the silicon at C9 favors two different main reaction pathways involving C14-methyl or C1-methylene migration through the stabilization of a C10 carbocation intermediate. Selective 1,2-migration of the bridgehead methyl group takes place with trisubstituted beta-epoxide and tetrasubstituted alpha-epoxide, yielding 4-hydroxy-eremophilane and 15-nor-eremophilane compounds, while the trisubstituted alpha-epoxide suffers successive rearrangements to give a 1-hydroxy-15-nor-eremophilane through a pathway involving the initial migration of the C1 methylene. The synthetic utility of these rearrangements is shown by the synthesis of natural (-)-aristolochene.

show abstract

“…This strategy has been used by Hwu in a total synthesis of solavetivone from carvone . Furthermore, we have shown that it is possible to achieve selective migration of the C9 methylene or C14 methyl groups by properly choosing the disposition between the TMS group and the epoxide, so selective migration of the C9 methylene group is observed when they are both in the same ring …”

mentioning

confidence: 93%

Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-β-rotunol and All Diastereomers of 6,11-Spirovetivadiene

et al. 2004

Self Cite

View full text Add to dashboard Cite

The synthesis of the spirovetivane sesquiterpenes (+)-anhydro-beta-rotunol and all the diastereomers of 6,11-spirovetivadiene in enantiomerically pure form has been achieved starting from santonin. The key step is the silicon-guided acid-promoted rearrangement of a 1-trimethylsilyl-4,5-epoxyeudesmane prepared from santonin in several steps involving lactone reductive opening, conjugate addition of TMSLi-CuCN, deoxygenation of a carbonyl group, and epoxidation. Rearrangement of the epoxide gave a spiro[4,5]decanediol which was used as a synthetic intermediate. From this compound, (+)-anhydro-beta-rotunol was prepared after elimination of the primary hydroxyl group in the side chain, followed by allylic oxidation at C8 and elimination of the tertiary hydroxyl group in the cyclohexane ring. On the other hand, elimination of the hydroxyl group in the side chain and reduction of the hydroxyl in the cyclohexane ring gave (-)-premnaspirodiene and (-)-hinesene. The synthesis of the rest of the diastereomers for these compounds required formal inversion of the C5 spiro carbon. The synthesis of these compounds showed that the structure of (-)-agarospirene isolated from Scapania sp. was erroneously assigned, and it has been corrected to be identical to that of (-)-hinesene.

show abstract

Silicon-guided rearrangement of 10-methyl-4,5-epoxydecalins. Methyl versus methylene migration

Cited by 6 publications

References 23 publications

Synthesis of Sesquiterpenes via Silicon-Guided Rearrangement of Epoxydecalins

Synthesis of Sesquiterpenes via Silicon-Guided Rearrangement of Epoxydecalins

Rearrangement of 4,5-Epoxy-9-trimethylsilyldecalines. Application to the Synthesis of the Natural Eremophilane (−)-Aristolochene

Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-β-rotunol and All Diastereomers of 6,11-Spirovetivadiene

Contact Info

Product

Resources

About