Chemistry of meso-Dimethylaminopropenyl- porphyrins and -bisporphyrins: the Synthesis of Australochlorin, a Benzochlorin Isomer.

1997 ◽  
Vol 50 (5) ◽  
pp. 487 ◽  
Author(s):  
Dmitry V. Yashunsky ◽  
Gelii V. Ponomarev ◽  
A. S. Moskovkin ◽  
Dennis P. Arnold
Keyword(s):  
Acetic Acid ◽  
Double Bond ◽  
Trifluoroacetic Acid ◽  
Membered Ring ◽  
Macrocyclic Complexes ◽  
Exocyclic Double Bond ◽  
Derivatives Of

The nickel(II) complex of meso-dimethylaminoprop-1-enyloctaethylporphyrin (2c) was converted by quaternization and thermolysis into a pair of novel isomeric macrocyclic complexes (3) and (4). These have a fused six-membered ring, and an exocyclic double bond on the neighbouring β-position, and have been named ‘australochlorins’. Heating these compounds in acetic acid leads to the known nickel(II) octaethylbenzochlorin (1) and a novel β-(1-acetoxyethyl)benzochlorin (5). Trifluoroacetic acid promotes the regioselective formation of benzochlorin/porphyrin species from the mononickel(II) complexes of the acrolein derivatives of bis(octaethylporphyrinyl)ethane and trans-ethene.

scholarly journals Chemoselective Ring-Opening Polymerization of Bio-Renewable α-Methylene-γ-Butyrolactone via an Organophosphazene/urea Binary Synergistic Catalytic System Toward a Sustainable Polyester

2020 ◽  
Author(s):  
Yong Shen ◽  
Wei Xiong ◽  
YongZheng Li ◽  
ZhiChao Zhao ◽  
Hua Lu ◽  
...  
Keyword(s):  
Double Bond ◽  
Catalytic System ◽  
Low Temperatures ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Unsaturated Polyester ◽  
Ring Opening Polymerization ◽  
Membered Ring ◽  
Exocyclic Double Bond ◽  
Binary Catalyst

Despite the great potential of bio-renewable a-methylene-<a></a><a></a><a>g-butyrolactone</a> (MBL) to produce functional recyclable polyester, the ring-opening polymerization (ROP) of MBL remains as a challenge due to the competing polymerization of the highly reactive exocyclic double bond and the low strained five membered ring. In this contribution, we present the first organocatalytic chemoselective ROP of MBL to exclusively produce recyclable unsaturated polyester by utilizing a phosphazene base/urea binary catalyst. We show that delicate chemoselectivity can be realized by controlling the temperature and using selected urea catalysts. Experimental and theoretical calculations provide mechanistic insights and indicate that the kinetically controlled ROP pathway is favored by using urea with stronger acidity at low temperatures.

Ozonolysis of Derivatives of Labda-8(17),14-dien-13-ol (Manool) and Their Conversion Into Large Ring Unsaturated Lactones

1988 ◽  
Vol 41 (5) ◽  
pp. 711 ◽  
Author(s):  
PK Grant ◽  
KL Chee ◽  
JS Prasad ◽  
MY Tho
Keyword(s):  
Double Bond ◽  
Good Yield ◽  
Spatial Relationship ◽  
Hydroxyl Group ◽  
Exocyclic Double Bond ◽  
Large Ring ◽  
Unsaturated Lactones ◽  
Derivatives Of

Dehydration of the unstable hydroperoxy ethers (4) and (6) formed on ozonolysis of the manool derivatives (2) and (5) resulted in the formation of the ten- membered unsaturated lactones (11) and (12) in good yield. The results of an investigation into the nature of the hydroxyl group and its spatial relationship to the exocyclic double bond in lactone formation are reported for other manool derivatives.

Acid-catalyzed migration of N4-acyl groups in cytosine derivatives

1979 ◽  
Vol 44 (6) ◽  
pp. 1819-1827 ◽  
Author(s):  
Antonín Holý
Keyword(s):  
Acetic Acid ◽  
Trifluoroacetic Acid ◽  
The Other ◽  
Aqueous Acetic Acid ◽  
Amino Group ◽  
Benzoyl Group ◽  
Benzoyl Cyanide ◽  
Acid Catalyzed ◽  
Derivatives Of ◽  
Anhydrous Acetic Acid

Heating 1-(2,3-di-O-benzoyl-β-D-arabinofuranosyl)-N4-benzoylcytosine (I) in 80% acetic acid afforded 1-(2,3-di-O-benzoyl-β-D-arabinofuranosyl)-N3-benzoylcytosine (II). Benzoylation of 5'-O-tritylcytidine (V) led to the 2',3',N4-tribenzoyl derivative VI which was refluxed with 80% acetic acid to give 2',3',N3-tribenzoylcytidine (VII). Analogously, 2',3',5',N4-tetrabenzoylcytidine (IX), prepared by benzoylation of cytidine with benzoyl cyanide, gave on reflux with 80% acetic acid 2',3',5',N3-tetrabenzoylcytidine (X). Under identical conditions, 1-methyl-N4-benzoylcytosine (XI) afforded directly 1-methyluracil (XII) .This migration takes place also in acetyl derivatives of cytosine nucleosides: 2',3',5',N4-tetraacetylcytidine (XIII) was transformed to the N3-acetylcytosine derivative XIV. On the other hand, migration of acetyl or benzoyl group from the exo-amino group of adenine has not been observed under the mentioned conditions. The migration of the N4-acyl group of cytosine derivatives proceeds best in aqueous acetic acid, more slowly also in anhydrous acetic acid, but not by action of trifluoroacetic acid in 1,2-dichloroethane.

Synthesis of 1,2,4-triazine-3,5(2H,4H)-diones containing electronegative substituents in position 6

1983 ◽  
Vol 48 (9) ◽  
pp. 2676-2681 ◽  
Author(s):  
Jiří Farkaš
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Nitro Compound ◽  
Trifluoroacetic Acid ◽  
Acid Synthesis ◽  
Amino Derivative ◽  
Effect Of Substituents ◽  
Fluoro Derivative ◽  
Cuprous Cyanide ◽  
Derivatives Of

Reaction of fluorine with 1,2,4-triazine-3,5(2H,4H)-dione (I) in acetic acid afforded the 6-fluoro derivative II in low yield. The 6-nitro compound III was prepared by oxidation of the 6-amino derivative of compound I with hydrogen peroxide in trifluoroacetic acid. Synthesis of the 6-cyano compound IV was accomplished by treatment of the 6-bromo derivative with cuprous cyanide in N,N,N',N'-tetramethylurea. The effect of substituents on the carbonyl frequencies for 6-substituted derivatives of I was studied.

ChemInform Abstract: SYNTHESIS OF DERIVATIVES OF TRICYCLO(2.1.0.02,5)PENTANE WITH AN EXOCYCLIC DOUBLE BOND

1977 ◽  
Vol 8 (32) ◽  
pp. no-no
Author(s):  
N. S. ZEFIROV ◽  
N. V. AVERINA ◽  
A. M. BOGANOV ◽  
T. S. KUZNETSOVA ◽  
S. S. YAROVOI
Keyword(s):  
Double Bond ◽  
Exocyclic Double Bond ◽  
Derivatives Of

A Model Compound for Anhydroryanodol

1972 ◽  
Vol 50 (24) ◽  
pp. 4013-4021 ◽  
Author(s):  
Brian G. Brownlee ◽  
Pak-Tsun Ho ◽  
K. Wiesner
Keyword(s):  
Double Bond ◽  
Model Compound ◽  
Membered Ring ◽  
Exocyclic Double Bond

The synthesis of the acetoxy lactone 17 by a method potentially suitable for anhydroryanodine is described. In the course of the synthesis several mechanistically unusual reactions were observed. One of them was an attack of Cl+ on an exocyclic double bond in a benzobicycloheptane system from the endo side. Another was a SN2 type displacement of chlorine by chloride or acetate ions in a six-membered ring.

scholarly journals Chemoselective Ring-Opening Polymerization of Bio-Renewable α-Methylene-γ-Butyrolactone via an Organophosphazene/urea Binary Synergistic Catalytic System Toward a Sustainable Polyester

2020 ◽  
Author(s):  
Yong Shen ◽  
Wei Xiong ◽  
YongZheng Li ◽  
ZhiChao Zhao ◽  
Hua Lu ◽  
...  
Keyword(s):  
Double Bond ◽  
Catalytic System ◽  
Low Temperatures ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Unsaturated Polyester ◽  
Ring Opening Polymerization ◽  
Membered Ring ◽  
Exocyclic Double Bond ◽  
Binary Catalyst

Despite the great potential of bio-renewable a-methylene-<a></a><a></a><a>g-butyrolactone</a> (MBL) to produce functional recyclable polyester, the ring-opening polymerization (ROP) of MBL remains as a challenge due to the competing polymerization of the highly reactive exocyclic double bond and the low strained five membered ring. In this contribution, we present the first organocatalytic chemoselective ROP of MBL to exclusively produce recyclable unsaturated polyester by utilizing a phosphazene base/urea binary catalyst. We show that delicate chemoselectivity can be realized by controlling the temperature and using selected urea catalysts. Experimental and theoretical calculations provide mechanistic insights and indicate that the kinetically controlled ROP pathway is favored by using urea with stronger acidity at low temperatures.

Biochemically important reactions of 2-furylethylenes. Reactions with low-molecular thiols

1982 ◽  
Vol 47 (5) ◽  
pp. 1523-1529 ◽  
Author(s):  
Ernest Šturdík ◽  
Tibor Liptaj ◽  
Štefan Baláž ◽  
Ľudovít Drobnica
Keyword(s):  
Biological Activity ◽  
Double Bond ◽  
Aqueous Medium ◽  
Exocyclic Double Bond ◽  
Nmr Analysis ◽  
Sh Groups ◽  
Derivatives Of

As evidenced by spectrophotometry and radiochromatography, derivatives of 2-furylethylene are able to react with thiols in an aqueous medium. The NMR analysis of reaction mixture showed that the site attacked by the thiol is the more electrophilic C(1) atom of the exocyclic double bond of the 2-furylethylenes under study. The ability to react with SH groups is of extraordinary importance particularly in connection with the study of mechanism of biological activity of 2-furylethylenes.

scholarly journals Synthesis of novel spiro-isoxazoline and spiro-isoxazolidine derivatives of tomentosin

RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6523-6529 ◽  
Author(s):  
Mohamed Zaki ◽  
Abdelouahd Oukhrib ◽  
Mohamed Akssira ◽  
Sabine Berteina-Raboin
Keyword(s):  
Double Bond ◽  
Dipolar Cycloaddition ◽  
Exocyclic Double Bond ◽  
Enantiomerically Pure ◽  
Nitrile Oxides ◽  
Dittrichia Viscosa ◽  
Derivatives Of

A series of novel enantiomerically pure spiro-(isoxazolidines/isoxazolines) were synthesized regioselectively by 1,3-dipolar cycloaddition using nitrones and nitrile oxides, on the exocyclic double bond of tomentosin extracted from Dittrichia viscosa.

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