Tetracyclic triterpenes. VIII. The skeletal rearrangement of 3β-acetoxy-9α,11α-epoxy-5α-lanostan-7-one: 13- and 10-methyl group migration

1985 ◽  
Vol 63 (6) ◽  
pp. 1280-1286 ◽  
Author(s):  
Zdzisław Paryzek ◽  
Roman Wydra
Keyword(s):  
Acetic Anhydride ◽  
Spectral Data ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Major Product ◽  
Chemical Transformations ◽  
Skeletal Rearrangement ◽  
Methyl Group ◽  
Group Migration

The boron trifluoride etherate catalyzed rearrangement of 3β-acetoxy-9α, 11α-epoxy-5α-lanostan-7-one (1) in acetic anhydride resulted in formation of 19(10 → 9β)abeo compounds 2 and 4 along with 18(13 → 12β)abeo compound 5, as the major product. These structures are supported by spectral data and chemical transformations. The possible mechanism of the rearrangement is discussed.

Novel Transformation of Methoxy Tetralones During Demethylation with Boron Trifluoride Etherate and Acetic Anhydride.

ChemInform ◽  
2005 ◽  
Vol 36 (6) ◽  
Author(s):  
Ajoy K. Banerjee ◽  
Liadis Bedoya ◽  
William J. Vera ◽  
Carlos Melean ◽  
Henry Mora ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate

Acid-catalyzed rearrangements of an A(1)-nor-triterpenoid 2α,3α-epoxide

1989 ◽  
Vol 54 (2) ◽  
pp. 413-429 ◽  
Author(s):  
Jiří Klinot ◽  
Jiří Liška ◽  
Alena Forgáčová ◽  
Miloš Buděšínský ◽  
Jiří Protiva ◽  
...  
Keyword(s):  
Acidic Medium ◽  
Boron Trifluoride ◽  
Mass Spectra ◽  
Boron Trifluoride Etherate ◽  
Methyl Group ◽  
Unsaturated Alcohols ◽  
Acid Catalyzed ◽  
C Nmr

Reactions of 2α,3α-epoxide X, derived from 19β,28-epoxy-A(1)-nor-18α-oleanane, with acids proceed with migration of the 10β-methyl group into the position 2β, giving rise to unsaturated alcohols XII and XIV and diene IX. Reaction with boron trifluoride etherate afforded ketone XI in addition to XII and XIV. Olefin VIII rearranged in acidic medium to give olefins XXVI and XXVII. The rearranged products were converted into other derivatives and their structure was established by 1H and 13C NMR, IR, UV and mass spectra.

The rearrangement of some epoxy podocarpanoic acids

1977 ◽  
Vol 30 (5) ◽  
pp. 1093 ◽  
Author(s):  
WS Hancock ◽  
LN Mander ◽  
RA Massy-Westropp
Keyword(s):  
Sulphuric Acid ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Methyl Group

Rearrangement of the epoxides derived from the podocarpenoic acids (3b), (3d) and (5b) with boron trifluoride etherate gave compounds with the rosane skeleton, lacking substituents at C 13. The rearrangement involves the shift of a methyl group with concomitant lactonization. The unsaturated acids (3b) and (5b) undergo similar rearrangements when they are treated with boron trifluoride etherate or sulphuric acid.

Novel Transformation of Methoxy Tetralones During Demethylation with Boron Trifluoride Etherate and Acetic Anhydride

2004 ◽  
Vol 34 (18) ◽  
pp. 3399-3408 ◽  
Author(s):  
Ajoy K. Banerjee ◽  
Liadis Bedoya ◽  
William J. Vera ◽  
Carlos Melean ◽  
Henry Mora ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate

Cyclization of 17-ethylenedioxy-3α,5-cyclo-6,7-seco-5α-androstane-6,7-diol

1979 ◽  
Vol 44 (1) ◽  
pp. 128-144 ◽  
Author(s):  
Helena Velgová ◽  
Dietrich Zeigan ◽  
Günther Engelhardt ◽  
Antonín Trka
Keyword(s):  
Acetic Anhydride ◽  
Intramolecular Cyclization ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Mass Spectrometric ◽  
Cyclic Ethers ◽  
Mass Spectrometric Data ◽  
Spectrometric Data ◽  
H Nmr ◽  
C Nmr

Intramolecular cyclization of 17-ethylenedioxy-3α,5-cyclo-6,7-seco-5α-androstane-6,7-diol (I) on treatment with p-toluenesulphonyl chloride in pyridine gives 17-ethylenedioxy-3α,5-cyclo-B-homo-7-oxa-5α-androstane (III) and 17-ethylenedioxy-3,5-methylene-6-oxaandrostane (II). The cyclic ethers II and III after deketalization and treatment with boron trifluoride etherate in acetic anhydride yield 3β,7-dihydroxy-6,7-secoandrost-5-en-17-one (XIV) along with a small quantity of 3β,5-cyclo-A-homo-6-oxa-5β-androstane-17-one (XIII). Proof of the structures in question is based on IR, 1H NMR, 13C NMR and mass spectrometric data.

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