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1.
Org Lett ; 22(16): 6543-6546, 2020 08 21.
Article in English | MEDLINE | ID: mdl-32806139

ABSTRACT

An effective one-pot synthesis of either indoles or pyrazoles can be achieved via Pd-catalyzed aminations followed by subsequent cyclizations facilitated by aqueous micellar catalysis. This new technology includes efficient couplings with low loadings of palladium, a more stable source of the required hydrazine moiety, greater atom economy for the initial coupling, and reduced reaction temperatures, all leading to environmentally responsible processes.

2.
Org Lett ; 22(13): 4949-4954, 2020 07 02.
Article in English | MEDLINE | ID: mdl-32551706

ABSTRACT

Palladium-catalyzed allylic substitution, or "Tsuji-Trost" reactions, can be run under micellar catalysis conditions featuring not only chemistry in water but also numerous combinations of reaction partners that require low levels of palladium, typically on the order of 1000 ppm (0.1 mol %). These couplings are further characterized by especially mild conditions, leading to a number of cases not previously reported in an aqueous micellar medium. Inclusion of diverse nucleophiles, such as N-H heterocycles, alcohols, dicarbonyl compounds, and sulfonamides is described. Intramolecular cyclizations further illustrate the broad utility of this process. In addition to recycling studies, a multigram scale example is reported, indicative of the prospects for scale up.

3.
Nat Protoc ; 14(4): 1108-1129, 2019 04.
Article in English | MEDLINE | ID: mdl-30903108

ABSTRACT

Amide bond formation and aromatic/heteroaromatic nitro-group reductions represent two of the most commonly used transformations in organic synthesis. Unfortunately, such processes can be especially wasteful and hence environmentally harmful, and may present safety hazards as well, given the reaction conditions involved. The two protocols herein describe alternative technologies that offer solutions to these issues. Polypeptides can now be made in water at ambient temperatures using small amounts of the designer surfactant TPGS-750-M, thereby eliminating the use of organic solvents as the reaction medium. Likewise, a safe, inexpensive and efficient procedure is outlined for nitro-group reductions, using industrial iron in the form of carbonyl iron powder (CIP), an inexpensive item of commerce. The peptide synthesis will typically take, overall, 3-4 h for a simple coupling and 8 h for a two-step deprotection/coupling process. The workup usually consists of a simple extraction and acidic/basic aqueous washings. The nitro reduction procedure will typically take 6-8 h to complete, including setup, reaction time and workup.


Subject(s)
Chemistry Techniques, Synthetic , Green Chemistry Technology , Peptides/chemical synthesis , Surface-Active Agents/chemistry , Water/chemistry , Amides/chemistry , Catalysis , Humans , Hydrogen-Ion Concentration , Kinetics , Micelles , Oxidation-Reduction , Polyethylene Glycols/chemistry , Temperature , Vitamin E/chemistry
4.
ChemSusChem ; 12(13): 3159-3165, 2019 Jul 05.
Article in English | MEDLINE | ID: mdl-30889298

ABSTRACT

Several types of reduction reactions in organic synthesis are performed under aqueous micellar-catalysis conditions (in water at ambient temperature), which produce a significant volume of foam owing to the combination of the surfactant and the presence of gas evolution. The newly engineered surfactant "Coolade" minimizes this important technical issue owing to its low-foaming properties. Coolade is the latest in a series of designer surfactants specifically tailored to enable organic synthesis in water. This study reports the synthesis of this new surfactant along with its applications to gas-involving reactions.

5.
Org Lett ; 20(10): 2902-2905, 2018 05 18.
Article in English | MEDLINE | ID: mdl-29738254

ABSTRACT

Use of B-sp3-alkyl reagents for Suzuki-Miyaura couplings under aqueous micellar catalysis conditions is reported. Studies as to substrate scope, use in a four-step one-pot sequence, and reaction medium recycling exemplify the synthetic utility of this technology. OBBD ( B-alkyl-9-oxa-10-borabicyclo[3.3.2]decane) derivatives are easily made and utilized for couplings under mild conditions. Comparisons were also made between OBBD and 9-BBN ( B-alkyl-9-borabicyclo[3.3.1]nonane) derivatives as reaction partners.

6.
Org Lett ; 19(24): 6518-6521, 2017 12 15.
Article in English | MEDLINE | ID: mdl-29206473

ABSTRACT

An especially mild, safe, efficient, and environmentally responsible reduction of aromatic and heteroaromatic nitro-group-containing educts is reported that utilizes very inexpensive carbonyl iron powder (CIP), a highly active commercial grade of iron powder. These reductions are conducted in the presence of nanomicelles composed of TPGS-750-M in water, a recyclable aqueous micellar reaction medium. This new technology also shows broad scope and scalability and presents opportunities for multistep one-pot sequences involving this reducing agent.

7.
Org Lett ; 19(1): 194-197, 2017 01 06.
Article in English | MEDLINE | ID: mdl-27997200

ABSTRACT

The impact of varying percentages of an organic solvent added to reactions run in aqueous nanomicelles as the reaction medium has been investigated. Issues such as rates of reaction, percent conversion, and yield, as well as various practical aspects (e.g., effect on stirring, etc.), are discussed, leading to an operationally simple method for the general improvement of potentially problematic systems across a broad range of reaction types, in particular for reactions run at scale.

8.
Biointerphases ; 10(2): 021001, 2015 Jun 25.
Article in English | MEDLINE | ID: mdl-25810273

ABSTRACT

The generation of air-based plasmas under atmospheric plasma conditions was studied to assess their antimicrobial efficacy against commonly found pathogenic bacteria. The mixture of initial gases supplied to the plasma was found to be critical for the formation of bactericidal actives. The optimal gas ratio for bactericidal effect was determined to be 99% nitrogen and 1% oxygen, which led to a 99.999% reduction of a pathogenic strain of Escherichia coli on stainless steel surfaces. The experimental substrate, soil load on the substrate, flow rate of the gases, and addition of ethanol vapor all were found to affect antimicrobial efficacy of studied plasmas. Optical emission spectroscopy was used to identify the species that were present in the plasma bulk phase for multiple concentrations of nitrogen and oxygen ratios. The collected spectra indicate a unique series of bands present in the ultraviolet region of the electromagnetic spectrum that can be attributed to nitric oxide species known to be highly antimicrobial. This intense spectral profile dramatically changes as the concentration of nitrogen decreases.


Subject(s)
Air , Anti-Bacterial Agents/pharmacology , Atmospheric Pressure , Escherichia coli/drug effects , Ethanol/pharmacology , Plasma Gases/pharmacology , Water/pharmacology , Environmental Microbiology , Escherichia coli/physiology , Microbial Viability/drug effects , Plasma Gases/chemistry , Spectrum Analysis
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