Search results for "Cyclic compound"

Synthesis of conformationally restricted 1,2,3-triazole-substituted ethyl β- and γ-aminocyclopentanecarboxylate stereoisomers. Multifunctionalized al…

2010

Abstract Stereoisomers of 1,2,3-triazole-functionalized, conformationally restricted β- or γ-amino esters with a cyclopentane skeleton were efficiently synthetized from the bicyclic β-lactam 6-azabicyclo[3.2.0]hept-3-en-7-one (1) and Vince γ-lactam (15) in five or six steps involving the azide–alkyne 1,3-dipolar cycloaddition of azido-substituted amino ester stereoisomers with nonsymmetric acetylenes. The azide–alkyne click reactions were investigated under thermal and Cu(I)-catalyzed conditions. Surprisingly, the thermally induced cycloaddition furnished the corresponding 1,4-triazoles regioselectively, which also took place selectively in response to Cu(I) catalysis.

Interaction between 24-hydroxycholesterol, oxidative stress, and amyloid-β in amplifying neuronal damage in Alzheimer’s disease: three partners in cr…

2011

All three cholesterol oxidation products implicated thus far in the pathogenesis of Alzheimer's disease, 7β-hydroxycholesterol, 24-hydroxycholesterol, and 27-hydroxycholesterol, markedly enhance the binding of amyloid-beta (Aβ) to human differentiated neuronal cell lines (SK-N-BE and NT-2) by up-regulating net expression and synthesis of CD36 and β1-integrin receptors. However, only 24-hydroxycholesterol markedly potentiates the pro-apoptotic and pro-necrogenic effects of Aβ(1-42) peptide on these cells: 7β-hydroxycholesterol and 27-hydroxycholesterol, like unoxidized cholesterol, show no potentiating effect. This peculiar behavior of 24-hydroxycholesterol at physiologic concentrations (1 μ…

ChemInform Abstract: Facile Synthesis of 2-Nitroalkanols by Tetramethylguanidine (TMG)- Catalyzed Addition of Primary Nitroalkanes to Aldehydes and A…

2010

Abstract Tetramethylguanidine-catalyzed addition of primary nitroalkanes to aldehydes and alicyclic ketones constitutes a practical means to perform the nitro-aldol reaction (Henry reaction). The very mild conditions employed, together with the short reaction times, make the procedure tolerant of a range of functionalities and highly versatile for the synthesis of a variety of 2-nitroalkanols.

Facile synthesis of 2-nitroalkanols by tetramethylguanidine (TMG)-catalyzed addition of primary nitroalkanes to aldehydes and alicyclic ketones

1997

Abstract Tetramethylguanidine-catalyzed addition of primary nitroalkanes to aldehydes and alicyclic ketones constitutes a practical means to perform the nitro-aldol reaction (Henry reaction). The very mild conditions employed, together with the short reaction times, make the procedure tolerant of a range of functionalities and highly versatile for the synthesis of a variety of 2-nitroalkanols.

ChemInform Abstract: Aliphatic and Alicyclic Aldehydes: Synthesis by Diels-Alder Reactions with Enals or Their Acetals

2009

Synthesis of Lamellarin D Trimethyl Ether and Lamellarin H via 6π-Electrocyclization.

2015

An electrocyclic ring closure of a 2-azapentadienyl anion generated in situ from a chalcone and glycine ester is the key step of an efficient synthesis of the pyrrole core of the lamellarin alkaloids. A recently developed scalable one-pot procedure provides multigram quantities of a 3,5-diaryl-4-iodopyrrole-2-carboxylate intermediate which is transformed in four further high-yielding operations including a one-pot Pomeranz–Fritsch alkylation/cyclization and an Ullmann-type lactone ring closure into the pentacyclic lamellarin skeleton.

ChemInform Abstract: Dienediolates of Unsaturated Carboxylic Acids in Synthesis. Synthesis of Cyclohexenones and Polycyclic Ketones by Tandem Michael…

2010

Abstract Substituted 2-cyclohexenones 4 to 7 and hexaxydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.

Dienediolates of unsaturated carboxylic acids in synthesis. Synthesis of cyclohexenones and polycyclic ketones by tandem Michael-Dieckmann decarboxyl…

1994

Abstract Substituted 2-cyclohexenones 4 to 7 and hexaxydronaphthalenones and hexahydroindenones 13 to 18 are prepared by tandem Michael-Dieckmann addition of lithium dienediolates of acyclic and alicyclic unsaturated carboxylic acids to the lithium salts of the same or other unsaturated carboxylic acids.

Reductive transformations - 11. stereoselective cycloannelation and bridging of the cyclooctatetraene dianionMakromol. Chem., Rapid. Commun. 1988, 9,…

1988

Abstract Bifunctional electrophiles with C4-, C6-, and C8-chains are reacted with the cyclooctatetraene dianion to selectively give novel cycloannelation and bridging products which possess a surprising stereochemistry and are useful starting compounds for further syntheses.

Mandelamide-zinc-catalyzed enantioselective alkyne addition to heteroaromatic aldehydes.

2006

The (S,S)-mandelamide III catalyzes the additions of both aryl- and alkylalkynylzinc reagents to heteroaromatic aldehydes with good yields and enantioselectivities up to 92%. This catalyst is easily prepared in a one-step procedure, and both enantiomers are available. Unlike most other described methods, using this catalyst does not require the addition of Ti(O(i)Pr)4.