Chemoselective in situ protection of aldehydes and ketones using titanium tetrakis(dialkylamides)

1983 ◽  
pp. 406 ◽  
Author(s):  
Manfred T. Reetz ◽  
Brend Wenderoth ◽  
Roland Peter
Keyword(s):  
Aldehydes And Ketones

Nickel-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Hydrazones

2019 ◽  
Author(s):  
Leiyang Lv ◽  
Dianhu Zhu ◽  
Zihang Qiu ◽  
Jianbin Li ◽  
Chao-Jun Li
Keyword(s):  
Catalytic Method ◽  
Unsaturated Hydrocarbons ◽  
Carbon Nucleophiles ◽  
Aryl Aldehydes ◽  
Aldehydes And Ketones ◽  
Sterically Hindered

Hydroalkylation of unsaturated hydrocarbons with unstablized carbon nucleophiles is difficult and remains a major challenge. The disclosed examples so far mainly focused on the involvement of heteroatom and/or stabilized carbon nucleophiles as efficient reaction partners. Reported here is an unprecedented regioselective nickel-catalyzed hydroalkylation of 1,3-dienes with hydrazones, generated in situ from abundant aryl aldehydes and ketones and acted as both the sources of unstabilized carbanions and hydride. With this strategy, both terminal and sterically hindered internal dienes are hydroalkylated efficiently in a highly selective manner, thus providing a novel and reliable catalytic method to construct challenging C(sp3)-C(sp3) bonds.

Studies of Emissions from Oil Fires

1999 ◽  
Vol 1999 (1) ◽  
pp. 541-547 ◽  
Author(s):  
Mervin F. Fingas ◽  
Patrick Lambert ◽  
Ken Li ◽  
Zhendi Wang ◽  
Francine Ackerman ◽  
...  
Keyword(s):  
Crude Oil ◽  
Ground Level ◽  
Health Concern ◽  
Exposure Level ◽  
Emission Data ◽  
Combustion Gases ◽  
Aldehydes And Ketones ◽  
Polycyclic Aromatic ◽  
Exposure Levels

ABSTRACT Over 35 meso-scale burns were conducted to study various aspects of diesel and crude oil burning in situ. Extensive sampling and monitoring of these burns were conducted at downwind stations, upwind stations, and in the smoke plume. Particulate samples were taken in air and analyzed for polycyclic aromatic hydrocarbons (PAHs). PAHs were found to be lower in the soot than in the starting oil, although higher concentrations of the larger molecular PAHs were found in the soot and residue, especially for diesel burns. Particulates in the air were measured by several means, and were found to be greater than recommended exposure levels up to 500 meters downwind at ground level, depending on the size and type of fire. Diesel fires emit much more particulate matter and have longer exposure zones. Combustion gases, including carbon dioxide and carbon monoxide, were below exposure level maximums. Volatile organic compound (VOCs) emissions were measured, but the levels were less than from an evaporating crude oil spill. Over 140 compounds were identified and quantified. Carbonyls, including aldehydes and ketones, were found to be below human health concern levels. Emission data from over 30 experimental burns were used to develop prediction equations for over 150 specific compounds or emission categories. These were used to calculate safe distances and levels of concern for a standard burn size of 500 square meters, an amount that would typically be contained in a boom. The safe distance for a crude oil burn of this size is about 500 m and for a diesel burn, much farther.

A simple and efficient method for the synthesis of gem-diacetates from aldehydes and ketones catalysed by gallium triiodide

2005 ◽  
Vol 2005 (10) ◽  
pp. 659-660 ◽  
Author(s):  
Peipei Sun ◽  
Zhixin Hu
Keyword(s):  
Acetic Anhydride ◽  
Ambient Temperature ◽  
Efficient Method ◽  
Carbonyl Compounds ◽  
Aldehydes And Ketones

Aldehydes or ketones reacted with acetic anhydride in dichloromethane at ambient temperature to produce gem-diacetates in good to excellent yields in the presence of gallium triiodide, which was generated in situ from gallium and iodine. This catalyst was also useful for the deprotection of carbonyl compounds in the presence of water.

Sulfonated multiwalled carbon nanotubes (MWCNTs) as a new, efficient, and recyclable heterogeneous nanocatalyst for the synthesis of amines

2012 ◽  
Vol 90 (8) ◽  
pp. 701-707 ◽  
Author(s):  
M. M. Doroodmand ◽  
S. Sobhani ◽  
A. Ashoori
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Chemical Vapor ◽  
Catalytic Amount ◽  
Multiwalled Carbon ◽  
One Pot ◽  
Heterogeneous Nanocatalyst ◽  
Aldehydes And Ketones ◽  
Simple Filtration

Sulfonated multiwalled carbon nanotubes (MWCNTs) were synthesized by chemical vapor deposition (CVD) as a new and facile one-pot method using acetylene (as the CNT precursor), thiophene (as the sulfur precursor), and ferrocene (for in situ liberation of metal nanoparticles as the CNT nanocatalyst). A low catalytic amount of the resulting sulfonated MWCNTs with a turnover number (TON) up to 980 and a turnover frequency (TOF) up to 11 160 h–1 was utilized as a new and recyclable heterogeneous nanocatalyst for the efficient one-pot synthesis of various amines (secondary and tertiary) by direct reductive amination of aldehydes and ketones using NaBH4. The catalyst was easily isolated from the reaction mixture by simple filtration and reused at least five times without significant degradation in activity.

1996 Merck Frosst Award Lecture Synthetic adventures along a Rocky Mountain road

1997 ◽  
Vol 75 (9) ◽  
pp. 1163-1171 ◽  
Author(s):  
Brian A. Keay ◽  
Shawn P. Maddaford ◽  
Walter A. Cristofoli ◽  
Neil G. Andersen ◽  
Marco S. Passafaro ◽  
...  
Keyword(s):  
Suzuki Reaction ◽  
Rocky Mountain ◽  
Alder Reaction ◽  
Diels Alder ◽  
One Pot ◽  
Diels Alder Reaction ◽  
Aldehydes And Ketones ◽  
Palladium Catalyzed ◽  
Therapeutic Research

This paper describes the chemistry presented during the Merck Frosst Centre for Therapeutic Research Lecture Award given at the 79th Chemistry in Canada Conference held in St. John's, Newfoundland in June 1996. The first section describes the synthesis of (+)-xestoquinone using an asymmetric palladium-catalyzed polyene cyclization as the key step that creates the C and D rings and the stereogenic centre (68% ee) in one step. Extensions of the work involving an in situ Suzuki reaction are presented. The synthesis of C2-symmetric biaryls and the synthesis of a recently isolated binaphthyl natural product is described using this new method. A new one-pot desilylation–oxidation procedure of silyl ethers is described in detail for the preparation of aldehydes and ketones directly without the need for the isolation of the alcohol intermediate. Finally, a highly diastereoselective (>97%) Diels–Alder reaction is presented using (+)-cis,cis-spiro[4.4]nonane-1,6-diol as a new chiral auxiliary. One of the alcohols is attached to a pivalate, the other to an acrylate, and the Diels–Alder reaction with cyclopentadiene provides only one adduct (by 1H NMR and HPLC) with the endo stereochemistry. Keywords: (+)-xestoquinone, asymmetric palladium-catalyzed polyene cyclization, in situ Suzuki reaction, desilylation–oxidation reaction, spirodiols, chiral auxiliaries.

Microwave-assisted periselective annulation of triarylphosphenes with aldehydes and ketones

2020 ◽  
Vol 18 (46) ◽  
pp. 9526-9537
Author(s):  
Yun Luo ◽  
Zhicheng Fu ◽  
Xingyang Fu ◽  
Changle Du ◽  
Jiaxi Xu
Keyword(s):  
Nucleophilic Addition ◽  
Nucleophilic Attack ◽  
Microwave Assisted ◽  
Aldehydes And Ketones

Microwave-assisted and improved periselective synthesis of benzo-δ-phosphinolactones through the nucleophilic attack of in situ generated triarylphosphenes with aldehydes and ketones followed by intramolecular nucleophilic addition.

Synthesis of .alpha.-hydroxy ketones by direct, low-temperature, in situ nucleophilic acylation of aldehydes and ketones by acyllithium reagents

1992 ◽  
Vol 57 (21) ◽  
pp. 5620-5629 ◽  
Author(s):  
Dietmar Seyferth ◽  
Robert M. Weinstein ◽  
Richard C. Hui ◽  
Wei Liang Wang ◽  
Colin M. Archer
Keyword(s):  
Low Temperature ◽  
Hydroxy Ketones ◽  
Aldehydes And Ketones ◽  
Nucleophilic Acylation
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