PHOTOCHEMICAL TRANSFORMATIONS OF DIENES: I. THE PHOTOLYSIS OF 3-ALKOXYCHOLESTA-3,5-DIENES

1964 ◽  
Vol 42 (1) ◽  
pp. 79-83 ◽  
Author(s):  
George Just ◽  
Clifford C. Leznoff

The photolysis of 3-alkoxycholesta-3,5-dienes in an alcohol has been found to result in a stereospecific addition of the alcohol to the Δ3 double bond with formation of β,γ-unsaturated ketals. On silica gel, the non-cyclic β,γ-unsaturated ketals gave cholest-5-en-3-one.

ChemInform ◽  
1988 ◽  
Vol 19 (2) ◽  
Author(s):  
J. T. B. FERREIRA ◽  
W. O. CRUZ ◽  
P. C. VIEIRA ◽  
M. YONASHIRO

Author(s):  
A. K. Bauri ◽  
Sabine Foro ◽  
Nhu Quynh Nguyen Do

The title compound, C15H24O2{systematic name: 1-[6-hydroxy-7-(propan-2-yl)-4-methylidene-2,3,3a,4,5,6,7,7a-octahydro-1H-inden-1-yl]ethanone} was isolated fromA. reticulataby column chromatography over silica gel by gradient solvent elution. The molecule comprises a bicyclo[4.3.0]nonane ring bearing acetoxy, hydroxy and isopropyl substituents, and an exocyclic double bond on the cyclohexane ring. In the bicyclic skeleton, the cyclohexane ring adopts a chair conformation ring and the cyclopentane ring is in an envelope conformation. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming chains along [010]. These chains are cross-linked by C—H...O hydrogen bonds.


2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Maria Dewi Astuti ◽  
Evi Mintowati Kuntorini ◽  
Farah Eka Putri Wisuda

Abstrak Telah dilakukan penelitian yang bertujuan untuk mengidentifikasi senyawa kimia yang diisolasi dari fraksi n-butanol ekstrak metanol herba lampasau (Diplazium esculentum Swartz). Ekstrak metanol diperoleh secara maserasi dan difraksinasi berturut-turut denganpetroleum eter, etil asetat, dan n-butanol. Fraksi n­-butanol difraksinasidengan kromatografi kolom dengan fase diam silika gel dihasilkan fraksi A, B, C, dan D. Fraksi B dimurnikan dengan kromatografi lapis tipis preparatif pada silika geldihasilkan isolat B1. Isolat B1 berupa padatan tidak berwarna danberfluoresensi putih di bawah lampu UV 366 nm. Panjang gelombang maksimum pada spektra UV  isolat B1 adalah 225 nm dan 272.5 nm yang menunjukkan adanya ikatan rangkap tak terkonjugasi. Spektra IR isolat B1 menunjukkan adanya gugus C=C, –OH, C=O lakton, –CO, C–H ulur, dan C–H tekuk. Spektra 1H-NMR isolat B1 menunjukkan sinyal proton pada ikatan rangkap, proton –OH, proton pada –CH2 yang terikat atom oksigen, serta proton gugus metil –CH3. Berdasarkan data spektra UV, IR, dan 1H-NMR maka isolat B1 disarankan sebagai turunan senyawa triterpenoid hopan-lakton. Kata kunci : diplazium esculentum Swartz, fraksi n-butanol, triterpenoid hopan-lakton  Abstract The research  aims to identify chemical compounds isolated fromn-butanol fraction methanol extract of lampasau herbs (Diplazium esculentum Swartz). The methanol extract was obtained by maceration and fractioned by petroleum ether, ethyl acetate, andn-butanol. N-butanol fraction was fractionated using column chromatography on silica gel produced fractions A, B, C, and D. Fraction B was purified by preparative thin layer chromatography on silica gel produced isolate B1. Isolate B1was colorless solid and has white fluorescent under UV lamp 366 nm. The maximum wavelength on UV spectra of B1 are 225 nm and 272,5 nm indicates the unconjugated double bond. IR spectra of B1 showed the vibration of C=C, –OH, C=O lactone, –CO, C–H stretching and   C–H bending. Signals of 1H-NMR spectra of B1 showed the proton of double bond, –OH  proton, –CH2 proton bounded on oxygen atom, and –CH3 methyl proton. Based on data of spectra UV, IR, and 1H-NMR, isolate B1 suggested as a hopan triterpen derivative. Keywords : diplazium esculentum Swartz, n-butanol fraction, hopan-lactone triterpene


1987 ◽  
Vol 52 (16) ◽  
pp. 3698-3699 ◽  
Author(s):  
J. Tercio ◽  
B. Ferreira ◽  
W. O. Cruz ◽  
P. C. Vieira ◽  
M. Yonashiro

2011 ◽  
Vol 6 (7) ◽  
pp. 1934578X1100600
Author(s):  
Julio Rojas ◽  
Rosa Aparicio ◽  
Thayded Villasmil ◽  
Alexis Peña ◽  
Alfredo Usubillaga

Kaurenic acid (1a) is a tetracyclic diterpene that has an exocyclic double bond at Δ16. Isokaurenic acid (2a) has an endocyclic Δ15double bond. This compound has been isolated from Espeletia tenore (Espeletinae), a resinous plant from the Venezuelan Andes, but its occurrence is rare. In order to obtain a larger amount of 2a, the isomerization of 1a, which is easily obtained from other Espeletinae, was tried. Kaurenic acid methyl ester (1b) was treated with dil. HCl in CH3Cl/EtOH, after 6 h under reflux a yield of 41.5% isokaurenic acid methyl ester (2b) was obtained but 35.7% 16α-ethoxy-kauran-19-oic acid methyl ester (3b) had formed as a byproduct. Treating 1b with CF3COOH in refluxing CH2Cl2 permitted to obtain a yield of 66.6 % of 2b in 4 h and only traces of 16α-hydroxy-kauran-19-oic acid methyl ester (3a) as a byproduct. Both isomers were separated on a silica gel column impregnated with 20% AgNO3. Treating 2b with KOH in refluxing DMSO yielded pure isokaurenic acid, no back isomerization was observed.


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