Bufadienolides. 17. Synthesis of 14α- and 14β-Artebufogenin

1973 ◽  
Vol 51 (12) ◽  
pp. 1973-1976 ◽  
Author(s):  
Yoshiaki Kamano ◽  
George R. Pettit
Keyword(s):  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Perchloric Acid ◽  
Boron Trifluoride ◽  
Periodic Acid ◽  
Boron Trifluoride Etherate ◽  
Similar Reaction ◽  
Analogous Reaction ◽  
Dihydroxy Derivative

Treatment of resibufogenin (1a) or its acetate (1b) with perchloric acid or hydrochloric acid gave 14α-and 14β-artebufogenin (5a and 6a, or 5b and 6b), in addition to 15α-hydroxy-bufalin (4a or b). Reaction of epoxide 1b with chloranil or boron trifluoride etherate easily afforded 14α- and 14β-artebufogenin acetate (5b and 6b) in good yields. Analogous reaction of the isomeric 3β-hydroxy-14α,15α-epoxide 3a with perchloric acid, hydrochloric acid, or sulfuric acid again led to 14α- and 14β-artebufogenin (5a and 6a) and the 14β,15α-dihydroxy-derivative 4a, Similar reaction with periodic acid gave 6a and 4a.

General Method of Preparation of N-[(S)-(3-Hydroxy-2-phosphonomethoxypropyl)] Derivatives of Heterocyclic Bases

1993 ◽  
Vol 58 (5) ◽  
pp. 1151-1163 ◽  
Author(s):  
Petr Alexander ◽  
Antonín Holý
Keyword(s):  
Sodium Salt ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Cesium Carbonate ◽  
Analogous Reaction ◽  
Sodium Salts ◽  
Heterocyclic Bases ◽  
Derivatives Of ◽  
General Method ◽  
Methanolic Ammonia

Reaction of (R)-1-O-p-toluenesulfonyl-1,2,3-propanetriol (IV) with N-trimethylacetylimidazole (II) afforded (R)-1-O-p-toluenesulfonyl-3-O-trimethyacetyl-1,2,3-propanetriol (V) which was reacted with dimethoxymethane in the presence of phosphorus pentoxide to give (R)-2-O-methoxymethyl-1-O-p-toluenesulfonyl-3-O-trimethyacetyl-1,2,3-propanetriol (VI). Compound VI was treated with acetic anhydride and boron trifluoride etherate and the obtained 2-acetoxy derivative VII reacted with bromotrimethylsilane to give the intermediary bromomethyl ether VIII. Compound VIII on reaction with tris(2-propyl) phosphite afforded (R)-2-O-bis(2-propyl)phosphonomethyl-1-O-p-toluenesulfonyl-3-O-trimethyacetyl-1,2,3-propanetriol (IX). Condensation of synthon IX with sodium salts of adenine, 2,6-diaminopurine, or with cytosine, 6-azacytosine or 2-chloroadenine in the presence of cesium carbonate, afforded fully protected diesters X and XIIIb which on methanolysis and reaction with bromotrimethylsilane gave N-[(S)-(3-hydroxy-2-phosphonomethoxypropyl)] derivatives of adenine (XIa), 2- chloroadenine (XIb), 2,6-diaminopurine (XIc), cytosine (XIVa) and 6-azacytosine (XIVb). In an analogous reaction, sodium salt of 4-methoxy-2-pyrimidone reacted with compound IX to give an intermediate XIIIa which on treatment with methanolic ammonia and subsequent deblocking under the same conditions also afforded the cytosine derivative XIVa. Sodium salt of 2-amino-6-chloropurine was in this way converted into the corresponding 2-aminopurine derivative XVIII. Deprotection of this compound gave 9-(S)-(3-hydroxy-2-phosphonomethoxypropyl)-2-aminopurine (XIX).

Application of 2-Substituted Ethyl Isothiocyanates and 2-Aminothiols in the Synthesis of the Analogs of Indole Phytoalexin Camalexin

1999 ◽  
Vol 64 (9) ◽  
pp. 1448-1456 ◽  
Author(s):  
Milan Dzurilla ◽  
Martin Ružinský ◽  
Peter Kutschy ◽  
Jalpa P. Tewari ◽  
Vladimír Kováčik
Keyword(s):  
Antifungal Activity ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Alternaria Brassicicola ◽  
Magnesium Bromide ◽  
Alternaria Brassicae ◽  
Analogous Reaction ◽  
Cyclocondensation Reaction

Treatment of (indol-1-yl)magnesium bromide or iodide with 2-bromoethyl isothiocyanate afforded 1-(4,5-dihydrothiazol-2-yl)indole (6). Analogous reaction with 2,2-dimethoxyethyl isothiocyanate led to corresponding 1-thiocarbamoylindole derivative (7), which was cyclized to 1-(5-methoxy-4,5-dihydrothiazol-2-yl)indole (8) by treatment with boron trifluoride etherate. New analogs of camalexin, namely 4',5'-dihydrocamalexin (12) and benzocamalexin (14) were prepared by cyclocondensation reaction of 1-(tert-butoxycarbonyl)indole-3-carbaldehyde with cysteamine and 2-aminobenzenethiol. Antifungal activity of the prepared compounds was studied, using the fungi Alternaria brassicae and Alternaria brassicicola.

STEROIDS AND RELATED PRODUCTS: XIX. THE SYNTHESIS OF 3,9,12,20-TETRAOXYGENATED 9,12-seco STEROIDS. PART III. 11-AZA STEROIDS. PART I

1962 ◽  
Vol 40 (11) ◽  
pp. 2153-2162 ◽  
Author(s):  
Ch. R. Engel ◽  
S. Rakhit
Keyword(s):  
Methyl Ester ◽  
Ethylene Glycol ◽  
Ethyl Acetate ◽  
Good Yield ◽  
Boron Trifluoride ◽  
Osmium Tetroxide ◽  
Periodic Acid ◽  
Boron Trifluoride Etherate ◽  
The Other ◽  
Other Hand

The smooth conversion of 3β-acetoxy-5α-pregnane-12,20-dione (IV), readily available from hecogenin (I), to Δ9(11)-3β,20β-diacetoxy-5α-pregnan-12-one (VIII) is reported. Ozonolysis of this product in ethyl acetate gave, in almost 90% yield, 3β-hydroxy-20β-acetoxy-9-oxo-9,12-seco-11-nor-5α-pregnan-12-oic acid (XI), further characterized by its ester derivatives XIa and XIb. The conversion of the seco acid XI to Δ8(9)-3β-hydroxy-20β-acetoxy-9-amino-9,12-seco-11-nor-5α-pregnen-12-oic acid lactam (12 → 9) (XII) and thence to Δ8(9)-N-acetyl-3β,20β-diacetoxy-11-aza-5α-pregnene (XIVa), the first 11-aza steroids to be known, is described. On the other hand, Δ9(11)-3β,20β-diacetoxy-5α-pregnen-12-one (VIII) is readily transformed to the 9α,11α-glycol VII with osmium tetroxide and thence, with periodic acid, to 3β,9α-dihydroxy-20β-acetoxy-11-oxo-11,12-seco-5α-pregnan-12-oic acid (X), characterized as the methyl ester Xa and diacetoxy methyl ester Xb, and easily converted to the acetoxy hydroxy keto dicarboxylic seco acid XIII. In the course of this work it is shown that, whereas ketalization of the saturated 12,20-diketone IV with ethylene glycol and boron trifluoride etherate gives a good yield of the 12-monoketal (in accordance with the reports of the literature), treatment of the analogous 16-unsaturated 12,20-diketone with the same reagents under the same conditions leads not to ketal formation but to addition of ethylene glycol in position 16.

Three Hydrolysis Methods for 17-Ketosteroid Sulfates Compared by Colorimetric and Gas—Liquid Chromatographic Analyses

1970 ◽  
Vol 16 (3) ◽  
pp. 158-160 ◽  
Author(s):  
C A Muehlbaecher ◽  
E K Smith
Keyword(s):  
Gas Chromatography ◽  
Sulfuric Acid ◽  
Hydrochloric Acid ◽  
Ethyl Acetate ◽  
Perchloric Acid ◽  
Radioactivity Measurement ◽  
Liquid Chromatographic

Abstract Three methods for cleavage of 17-ketosteroid sulfates were evaluated for their acceptability in the preparation of urine extracts for gas chromatography. Recovery after hydrolysis with hot hydrochloric acid was unacceptably low, but solvolysis with ethyl acetate—sulfuric acid or tetrahydrofuran—perchloric acid was equally efficient and satisfactory. The results obtained by four techniques were intercompared: radioactivity measurement, Zimmermann- or Allen-chromogen development, and gas chromatography.

Synthesis of o-isopentenylphenols

1971 ◽  
Vol 24 (11) ◽  
pp. 2355 ◽  
Author(s):  
J Hlubucek ◽  
E Ritchie ◽  
WC Taylor
Keyword(s):  
Phosphoric Acid ◽  
Zinc Chloride ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Stannic Chloride ◽  
Counter Ion

The effect of the solvent and the counter-ion on the ring alkylation of 3- and 4-methoxyphenols by isopentenyl bromide has been examined. Under strictly anhydrous conditions good and consistent yields of the o- isopentenylphenols were obtained with the combination potassium- toluene, but sodium-toluene was more convenient. ��� Boron trifluoride etherate was more satisfactory than stannic chloride, zinc chloride, or phosphoric acid in catalysing the condensation of 3- and 4-methoxy-phenols with 2-methylbut-3-en-2-ol to the corresponding o-isopentenylphenols. Aryl α,α-dimethylpropargyl ethers were partially hydrogenated to the corresponding α,α- dimethylallyl ethers which rearranged in boiling N,N-diethyl-aniline to o-isopentenylphenols in high overall yield.

scholarly journals Synthesis of 5,6,7,8-Tetrahydroquinolines by Thermolysis of Oxime O-Allyl Ethers in the Presence of Boron Trifluoride Etherate.

1993 ◽  
Vol 41 (7) ◽  
pp. 1297-1298 ◽  
Author(s):  
Junko KOYAMA ◽  
Tamaki OGURA ◽  
Kiyoshi TAGAHARA ◽  
Masaaki MIYASHITA ◽  
Hiroshi IRIE
Keyword(s):  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
Allyl Ethers
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