N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XIII. Cleavage and Rearrangement Reactions of Pyrazolo[1,5-b][1,2,4,6]thiatriazine 1,1-Dioxides

2016 ◽  
Vol 69 (1) ◽  
pp. 61 ◽  
Author(s):  
Rebecca E. Norman ◽  
Michael V. Perkins ◽  
Andris J. Liepa ◽  
Craig L. Francis
Keyword(s):  
Ethyl Acetate ◽  
Dimethyl Sulfoxide ◽  
Trifluoroacetic Acid ◽  
Sulfonic Acid ◽  
Trifluoroacetic Anhydride ◽  
Ring Cleavage ◽  
Thermal Rearrangement ◽  
Heterocyclic Synthesis ◽  
Similar Treatment ◽  
Catalytic Hydrogenolysis

Treatment of pyrazolo[1,5-b][1,2,4,6]thiatriazines 1 with the Vilsmeier–Haack reagent afforded pyrazolo[1,5-a][1,3,5]triazines 5. Reaction of compounds 1 with trifluoroacetic anhydride, dimethyl sulfoxide, and triethylamine afforded 5-dimethylsulfanylidene derivatives 8. The guanidino-pyrazole-sulfonic acid 9 was produced from treatment of compounds 1 with trifluoroacetic acid under anhydrous conditions. Similar treatment in the presence of water afforded the desulfonated pyrazolo-guanidine 6. Reactions of 6 with one-carbon electrophiles provided various 4-substituted pyrazolo[1,5-a][1,3,5]triazines 5. Attempted catalytic hydrogenolysis of N7-benzyl pyrazolo[1,5-b][1,2,4,6]thiatriazines 2 in alcohols led to sulfamates 12 from thiatriazine ring cleavage. Ethyl acetate or tert-butanol as solvent allowed successful debenzylation to provide compounds 1. Aminolysis of compounds 2 gave sulfamides 13. Thermal rearrangement of compounds 2 afforded 6-benzyl-pyrazolo[3,4-e][1,2,4]thiadiazines 14.

Heterocyclic Synthesis With Azides. III. Reactions of Triazolines Made From Arylmethylidenemalonates

1994 ◽  
Vol 47 (7) ◽  
pp. 1375 ◽  
Author(s):  
RH Prager ◽  
P Razzino
Keyword(s):  
Dimethyl Sulfoxide ◽  
Sodium Azide ◽  
Trifluoroacetic Acid ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Heterocyclic Synthesis

Ethyl alkylidenemalonates reacted with sodium azide in dimethyl sulfoxide to give principally triazoles via the first-formed 4,5-dihydro-1H-1,2,3-tiriazoles. The triazolines themselves, and other compounds derived from them, were isolated in trace amounts. Ethyl alkylidenemalonates combined with benzyl azide in a 1,3-dipolar cycloaddition reaction to give 1-benzyl-4,5-dihydro-1H-1,2,3-triazoles. When treated with potassium t- butoxide in dimethyl sulfoxide , these adducts either aromatized to the corresponding triazoles, underwent deethoxycarbonylation but did not aromatize, or lost nitrogen to give ethyl benzylaminomethylidenemalonates. The proclivity for each of these three processes was determined by the C5 substituent of the 4,5-dihydro-1H-1,2,3-triazole. Treatment of the 1-benzyl-4,5-dihydro-1H-1,2,3-triazoles with trifluoroacetic acid gave ethyl diazomalonate.

HSCCC Separation of Three Main Compounds from the Crude Extract of Dracocephalum Tanguticum by Using Dimethyl Sulfoxide as Cosolvent

2020 ◽  
Author(s):  
Xue Yang ◽  
Yongling Liu ◽  
Tao Chen ◽  
Nana Wang ◽  
Hongmei Li ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethyl Acetate ◽  
Dimethyl Sulfoxide ◽  
Efficient Method ◽  
Crude Extract ◽  
High Speed ◽  
Glacial Acetic Acid ◽  
Butyl Alcohol ◽  
Preparative Hplc ◽  
Counter Current

Abstract Separation of natural compounds directly from the crude extract is a challenging work for traditional column chromatography. In the present study, an efficient method for separation of three main compounds from the crude extract of Dracocephalum tanguticum has been successfully established by high-speed counter-current chromatography (HSCCC). The crude extract was directly introduced into HSCCC by using dimethyl sulfoxide as cosolvent. Ethyl acetate/n-butyl alcohol/0.3% glacial acetic acid (4: 1: 5, v/v) system was used and three target compounds with purity higher than 80% were obtained. Preparative HPLC was used for further purification and three target compounds with purity higher than 98% were obtained. The compounds were identified as chlorogenic acid, pedaliin and pedaliin-6″-acetate.

Synthesis of para-olivetol depsides

1974 ◽  
Vol 27 (8) ◽  
pp. 1767 ◽  
Author(s):  
JA Elix
Keyword(s):  
Bond Formation ◽  
Trifluoroacetic Anhydride ◽  
Ester Bond ◽  
Catalytic Hydrogenolysis

The unambiguous synthesis of the lichen depsides, anziaic, perlatolic, 2'-O-methylanziaic, 2-O- methylperlatolic, 2'-O-methylperlatolic, 4-O-demethylplanaic, planaic, imbricaric and stenosporic acids is reported. Where necessary the phenolic and carboxy groups of the intermediate phenols were protected by O-benzylation until after the depside-ester bond formation had been achieved by treatment with trifluoroacetic anhydride. Catalytic hydrogenolysis of the depside esters so formed subsequently gave the natural acids.

Clean-Chemistry Sulfonation of Aromatics

2002 ◽  
Vol 2002 (7) ◽  
pp. 326-327 ◽  
Author(s):  
Brian W. Corby ◽  
Anthony D. Gray ◽  
Padraig J. Meaney ◽  
Michael J. Falvey ◽  
Gregory P. Lawrence ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Trifluoroacetic Acid ◽  
Trifluoroacetic Anhydride ◽  
Phase System

A solution of TFAA/H2SO4 is an atom-efficient liquid-phase system for rapid sulfonation of aromatic structures; H2SO4 is consumed stoichiometrically and the spent trifluoroacetic anhydride (TFAA) is readily recovered as trifluoroacetic acid (TFA) which can be recycled to TFAA.

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