scholarly journals Synthesis of 1,2-Dihydroquinolines via Hydrazine-Catalysed Ring-Closing Carbonyl-Olefin Metathesis

2019 ◽  
Author(s):  
Yunfei Zhang ◽  
Jae Hun Sim ◽  
Samantha N. Macmillan ◽  
Tristan Lambert
Keyword(s):  
Nitrogen Atom ◽  
Olefin Metathesis ◽  
Catalytic Cycle ◽  
Protecting Group ◽  
Acid Labile

The synthesis of 1,2-dihydroquinolines by the hydrazine-catalysed ring-closing carbonyl-olefin metathesis (RCCOM) of N-prenylated 2-aminobenzaldehydes is reported. Substrates with a variety of substitution patterns are shown, and the compatibility of these conditions with a range of additives is demonstrated. With an acid-labile protecting group on the nitrogen atom, in situ deprotection and autoxidation furnishes quinolines. In comparison to related oxygen-containing substrates, the cycloaddition step of the catalytic cycle is shown to be slower, but the cycloreversion is found to be more facile.

scholarly journals Synthesis of 1,2-Dihydroquinolines via Hydrazine-Catalysed Ring-Closing Carbonyl-Olefin Metathesis

2019 ◽  
Author(s):  
Yunfei Zhang ◽  
Jae Hun Sim ◽  
Samantha N. Macmillan ◽  
Tristan Lambert
Keyword(s):  
Nitrogen Atom ◽  
Olefin Metathesis ◽  
Catalytic Cycle ◽  
Protecting Group ◽  
Acid Labile

The synthesis of 1,2-dihydroquinolines by the hydrazine-catalysed ring-closing carbonyl-olefin metathesis (RCCOM) of N-prenylated 2-aminobenzaldehydes is reported. Substrates with a variety of substitution patterns are shown, and the compatibility of these conditions with a range of additives is demonstrated. With an acid-labile protecting group on the nitrogen atom, in situ deprotection and autoxidation furnishes quinolines. In comparison to related oxygen-containing substrates, the cycloaddition step of the catalytic cycle is shown to be slower, but the cycloreversion is found to be more facile.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

Cyclopropyldimethylcarbinyl: A new acid-labile side-chain protecting group for asparagine and glutamine

Peptides 1994 ◽  
1995 ◽  
pp. 155-156
Author(s):  
L. A. Carpino ◽  
H. N. Shroff ◽  
H.-G. Chao ◽  
E. M. E. Mansour ◽  
F. Albericio
Keyword(s):  
Side Chain ◽  
Protecting Group ◽  
Acid Labile

scholarly journals 2,3-Diaminopropanols Obtained from d-Serine as Intermediates in the Synthesis of Protected 2,3-l-Diaminopropanoic Acid (l-Dap) Methyl Esters

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1313
Author(s):  
Andrea Temperini ◽  
Donatella Aiello ◽  
Fabio Mazzotti ◽  
Constantinos M. Athanassopoulos ◽  
Pierantonio De Luca ◽  
...  
Keyword(s):  
Amino Acid ◽  
Reductive Amination ◽  
Methyl Esters ◽  
Primary Amines ◽  
Synthetic Approach ◽  
Protecting Group ◽  
Synthetic Strategy ◽  
Crude Product ◽  
Diaminopropanoic Acid ◽  
Acid Labile

A synthetic strategy for the preparation of two orthogonally protected methyl esters of the non-proteinogenic amino acid 2,3-l-diaminopropanoic acid (l-Dap) was developed. In these structures, the base-labile protecting group 9-fluorenylmethyloxycarbonyl (Fmoc) was paired to the p-toluensulfonyl (tosyl, Ts) or acid-labile tert-butyloxycarbonyl (Boc) moieties. The synthetic approach to protected l-Dap methyl esters uses appropriately masked 2,3-diaminopropanols, which are obtained via reductive amination of an aldehyde prepared from the commercial amino acid Nα-Fmoc-O-tert-butyl-d-serine, used as the starting material. Reductive amination is carried out with primary amines and sulfonamides, and the process is assisted by the Lewis acid Ti(OiPr)4. The required carboxyl group is installed by oxidizing the alcoholic function of 2,3-diaminopropanols bearing the tosyl or benzyl protecting group on the 3-NH2 site. The procedure can easily be applied using the crude product obtained after each step, minimizing the need for chromatographic purifications. Chirality of the carbon atom of the starting d-serine template is preserved throughout all synthetic steps.

Hexadienyloxycarbonyl (Hdoc) — A Mild Acid Labile Protecting Group for Amines.

ChemInform ◽  
2004 ◽  
Vol 35 (6) ◽  
Author(s):  
Iain Lingard ◽  
Gurdip Bhalay ◽  
Mark Bradley
Keyword(s):  
Protecting Group ◽  
Acid Labile ◽  
Mild Acid

Discovery of a Photoinduced Dark Catalytic Cycle Using in Situ LED-NMR Spectroscopy

2018 ◽  
Vol 140 (42) ◽  
pp. 13843-13853 ◽  
Author(s):  
Dan Lehnherr ◽  
Yining Ji ◽  
Andrew J. Neel ◽  
Ryan D. Cohen ◽  
Andrew P. J. Brunskill ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Catalytic Cycle

scholarly journals Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation

2012 ◽  
Vol 8 ◽  
pp. 456-460 ◽  
Author(s):  
Toshiki Nokami ◽  
Akito Shibuya ◽  
Yoshihiro Saigusa ◽  
Shino Manabe ◽  
Yukishige Ito ◽  
...  
Keyword(s):  
Low Temperature ◽  
Electrochemical Oxidation ◽  
Low Temperatures ◽  
Protecting Group ◽  
Triflic Acid ◽  
Electrochemical Generation ◽  
Stereoselective Glycosylation

Glycosyl triflates with a 2,3-oxazolidinone protecting group were generated from thioglycosides by low-temperature electrochemical oxidation. The glycosyl triflates reacted with alcohols to give the corresponding glycosides β-selectively at low temperatures. However, α-selectivity was observed in the absence of base at elevated reaction temperatures. In situ generated triflic acid promotes the isomerization of β-products to α-products.

Synthesis of Monobactams via the Diastereoselective Kinugasa Reaction

Synthesis ◽  
2018 ◽  
Vol 50 (10) ◽  
pp. 1991-2000 ◽  
Author(s):  
Kamil Kabala ◽  
Barbara Grzeszczyk ◽  
Bartłomiej Furman ◽  
Marek Chmielewski ◽  
Jolanta Solecka ◽  
...  
Keyword(s):  
Biological Activity ◽  
Nitrogen Atom ◽  
Carbon Atom ◽  
Bulky Substituent ◽  
Protecting Group ◽  
Acetylene Molecule ◽  
Cyclic Nitrones ◽  
Lactam Ring

The Kinugasa reaction between phthalimidoacetylene and cyclic nitrones derived from l-phenylglycine or l-serine and glyoxylic acid­, catalyzed by copper(I) chloride in the presence of triethylamine, is reported. The acetylene molecule approaches the nitrone exclusively anti to the bulky substituent next to the nitrogen atom to provide the cis-substituted β-lactam ring preferentially. The six-membered oxazinone ring can be easily opened, the phthaloyl residue can be transformed into a Boc protecting group, and substituents at the C-4 carbon atom and the nitrogen atom of the β-lactam ring can be easily removed or transformed into groups suitable for further synthesis of a variety of monobactam structures. Selected synthesized compounds were evaluated for their biological activity, showing interesting properties.

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