scholarly journals Action of tetrabutylammonium tribromide with para-substituted chalcones in protic and aprotic media

1995 ◽  
Vol 73 (9) ◽  
pp. 1526-1530 ◽  
Author(s):  
Jacques Berthelot ◽  
Yamina Benammar ◽  
Bernard Desmazières
Keyword(s):  
Double Bond ◽  
Main Reaction ◽  
Aprotic Solvents ◽  
Mild Conditions ◽  
Tetrabutylammonium Tribromide ◽  
High Yields

Bromination of the double bond of para-substituted chalcones under mild conditions in aprotic solvents is accomplished with high yields using tetrabutylammonium tribromide (TBABr3). In methanol, the main reaction is (α-β) bromomethoxylation. Stereoselectivity, regioselectivity, and chemioselectivity of this bromomethoxylation reaction are described. Keywords: bromination, bromomethoxylation, tetrabutylammonium tribromide, (α-β) dibromodihydrochalcones, α-bromo, β-methoxydihydrochalcones.

Palladium-catalysed Claisen rearrangement of 6-allyloxypurines

2013 ◽  
Vol 67 (1) ◽  
Author(s):  
Petr Koukal ◽  
Hana Dvořáková ◽  
Dalimil Dvořák ◽  
Tomáš Tobrman
Keyword(s):  
Double Bond ◽  
Claisen Rearrangement ◽  
Mild Conditions ◽  
High Yields

Abstract6-Allyloxypurines readily undergo palladium-catalysed Claisen rearrangement under mild conditions affording N 1-substituted hypoxanthines. In contrast with the previously reported protocol, the Claisen rearrangement can be performed using Pd(PPh3)4 or Pd(dba)2/dppf in dry THF at 60°C. The reaction can accommodate variously substituted allyl fragments to position N 1 of the hypoxanthine skeleton with high yields. Retention of the double bond configuration during rearrangement was observed.

scholarly journals Electrochemical multicomponent synthesis of 4-selanylpyrazoles under catalyst- and chemical-oxidant-free conditions

2021 ◽  
Author(s):  
Yan Wu ◽  
Jin-Yang Chen ◽  
Jing Ning ◽  
Xue Jiang ◽  
Jie Deng ◽  
...  
Keyword(s):  
Multicomponent Reaction ◽  
Raw Materials ◽  
Multicomponent Synthesis ◽  
Mild Conditions ◽  
Simple Protocol ◽  
High Yields

An electrochemical multicomponent reaction was established under catalyst-, chemical-oxidant-free and mild conditions, which provides an eco-friendly and simple protocol for constructing 4-selanylpyrazoles from easily available raw materials with high yields.

Hypervalent Iodine-Mediated Beckmann Rearrangement of Ketoximes

Synlett ◽  
2018 ◽  
Vol 29 (11) ◽  
pp. 1465-1468 ◽  
Author(s):  
Tomohiro Maegawa ◽  
Yasuyoshi Miki ◽  
Ryohei Oishi ◽  
Kazutoshi Segi ◽  
Hiromi Hamamoto ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Beckmann Rearrangement ◽  
Hypervalent Iodine ◽  
Mild Conditions ◽  
High Yields

We developed a Beckmann rearrangement employing hypervalent iodine reagent under mild conditions. The reaction of ketoxime with hypervalent iodine afforded the corresponding ketone, but premixing of hypervalent iodine and a Lewis acid was effective for promoting Beckmann rearrangement. Aromatic and aliphatic ketoximes were converted into their corresponding amides in good to high yields.

Ligand-Free Nickel-Catalyzed Reductive Allylic Defluorinative Cross-Coupling of α-Trifluoromethyl Alkenes with Epoxides

Synlett ◽  
2020 ◽  
Author(s):  
Chuan Wang ◽  
Zhiyang Lin ◽  
Yun Lan
Keyword(s):  
Ring Opening ◽  
Cross Coupling ◽  
Proton Donor ◽  
Mild Conditions ◽  
Ligand Free ◽  
High Yields ◽  
Radical Type

We report a reductive allylic defluorinative reaction of α-trifluoromethyl alkenes with terminal epoxides, which consists of an iodide-mediated regioselective ring opening and a nickel-catalyzed radical-type cross-coupling, providing diverse tertiary gem-difluorobishomoallylic alcohols in moderate to high yields. Notably, this reaction is conducted under mild conditions and requires no external ligand or proton donor.

scholarly journals Decarbonylation through Aldehydic C–H Bond Cleavage by a Cationic Iridium Catalyst

Synlett ◽  
2019 ◽  
Vol 30 (08) ◽  
pp. 972-976 ◽  
Author(s):  
Tomohiko Shirai ◽  
Kazuki Sugimoto ◽  
Masaya Iwasaki ◽  
Ryuki Sumida ◽  
Harunori Fujita ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Catalyst System ◽  
Mild Conditions ◽  
Iridium Catalyst ◽  
Reaction Proceeds ◽  
High Yields

We report the decarbonylation of aldehydes through an aldehydic C–H bond cleavage catalyzed by a cationic iridium/bisphosphine catalyst. The reaction proceeds under relatively mild conditions to give the corresponding hydrocarbon products in moderate to high yields. In addition, this cationic iridium catalyst system can be applied to an asymmetric hydroacylation of ketones.

Heterometallische Cluster durch ligandunterstützte Metallfragmentkondensation / Heterometallic Clusters by Ligand Assisted Metal Fragment Condensation

1991 ◽  
Vol 46 (9) ◽  
pp. 1169-1176 ◽  
Author(s):  
Wolfgang Rohde ◽  
Gert Fendesak
Keyword(s):  
Double Bond ◽  
Chelate Complexes ◽  
Heterometallic Clusters ◽  
X Ray ◽  
X Ray Crystallography ◽  
Inert Solvent ◽  
Fragment Condensation ◽  
Olefinic Double Bond ◽  
High Yields ◽  
Iron Fragment

Dicobalt complexes of 3-vinylpropargylic alcohol derivatives react with biscyclooctenetricarbonyliron to give new chelate complexes of the iron tricarbonyl fragment with the olefinic double bond and the alcohol oxygen atom bound to the iron fragment. These compounds react upon heating in an inert solvent to give FeCo-alkynyl cluster complexes in high yields. One of these compounds has been structurally characterized by X-ray crystallography.

p-Toluenesulfonic Acid Coated Natural Phosphate as an Efficient Catalyst for the Synthesis of 2-Substituted Benzimidazole

2018 ◽  
Vol 42 (12) ◽  
pp. 614-617
Author(s):  
Soumia Belkharchach ◽  
Hanane Elayadi ◽  
Hana Ighachane ◽  
Said Sebti ◽  
Mustapha Ait Ali ◽  
...  
Keyword(s):  
Environmentally Friendly ◽  
Catalytic Amount ◽  
Reusable Catalyst ◽  
Efficient Catalyst ◽  
Natural Phosphate ◽  
Mild Conditions ◽  
Toluenesulfonic Acid ◽  
High Yields

2-Substituted benzimidazoles are selectively synthesised in high yields via the condensation of o-phenylenediamine derivatives with aldehyde derivatives using catalytic amount of p-toluenesulfonic acid coated natural phosphate (NP/PTSA) under mild conditions. The use of NP/PTSA as a reusable catalyst makes this process simple, convenient, and environmentally friendly.

THE SOLVOLYSIS OF THE ALPHA- AND BETA-3,4,6-TRI-O-ACETYL-D-GLUCOPYRANOSYL CHLORIDES

1955 ◽  
Vol 33 (1) ◽  
pp. 128-133 ◽  
Author(s):  
R. U. Lemieux ◽  
G. Huber
Keyword(s):  
Acetic Acid ◽  
Double Bond ◽  
Positive Charge ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Double Bond Character ◽  
Ionic Reactions ◽  
Oxygen Bond ◽  
Bond Character ◽  
Anomeric Center

3,4,6-Tri-O-acetyl-β-D-glucopyranosyl chloride was found to undergo solvolysis in acetic acid to form 1,3,4,6-tetra-O-acetyl-α-D-glucopyranose as the main reaction product. The much less reactive anomeric α-chloride also appeared to undergo solvolysis with extensive inversion of the anomeric center. It is submitted that the tendencies for inversion obtained in these ionic reactions are due to the conformations imposed on the intermediate ions through distribution of the positive charge to the ring oxygen and the consequent introduction of double-bond character to the carbon-1 to ring-oxygen bond.

An Example of Ketone Olefination via Praseodymium-Mediated Barbier Reaction in the Presence of Diethyl Phosphite

Synlett ◽  
2019 ◽  
Vol 30 (12) ◽  
pp. 1437-1441
Author(s):  
Xu yan Cao ◽  
Fei Huang ◽  
Songlin Zhang
Keyword(s):  
Double Bond ◽  
Bond Formation ◽  
Point Of View ◽  
Diethyl Phosphite ◽  
Reaction Conditions ◽  
One Pot ◽  
Type Reaction ◽  
Mild Conditions ◽  
Allyl Halides ◽  
Barbier Reaction

The first example of carbon double-bond formation via praseodymium-mediated Barbier type reaction of ketones and allyl halides in the presence of diethyl phosphite is reported. The reaction is highly α-regioselective and conveniently carried out under mild conditions in a one-pot fashion. From a synthetic point of view, a series of conjugated alkenes were obtained in moderate to good yields in this one-pot reaction with practical reaction conditions.

Neodymium-Promoted Highly Selective Carbon–Carbon Double Bond Formation of Ketones with Allyl Halides in the Presence of Diethyl Phosphite

Synthesis ◽  
2020 ◽  
Vol 52 (22) ◽  
pp. 3446-3451
Author(s):  
Songlin Zhang ◽  
Dengbing Xie ◽  
Yiqiong Wang ◽  
Bo Yang
Keyword(s):  
Double Bond ◽  
Bond Formation ◽  
Point Of View ◽  
Diethyl Phosphite ◽  
Reaction Conditions ◽  
One Pot ◽  
Mild Conditions ◽  
Carbon Double Bond ◽  
Allyl Halides ◽  
First Time

The carbon–carbon double bond formation via neodymium-mediated Barbier-type reaction of ketones and allyl halides in the presence of diethyl phosphite is reported for the first time. The reaction is highly α-regioselective and was conveniently carried out under mild conditions in a one-pot fashion. From a synthetic point of view, a series of conjugated alkenes were obtained in moderate to good yields in this one-pot reaction with feasible reaction conditions.

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