Search results for "Bicyclic molecule"

Selective Transformation of Norbornadiene into Functionalized Azaheterocycles and β‐Amino Esters with Stereo‐ and Regiocontrol

2021

Novel functionalized azaheterocycles with multiple chiral centers have been accessed from readily available norbornene β-amino acids or β-lactams across a stereocontrolled synthetic route, based on ring-opening metathesis (ROM) of the staring unsaturated bicyclic amino esters, followed by selective cyclization through ring-closing metathesis (RCM). The RCM transformations have been studied under various experimental conditions to assess the scope of conversion, catalyst, yield, and substrate influence. The structure of the starting norbornene β-amino acids predetermined the structure of the new azaheterocycles, and the developed synthetic route took place with the conservation of the config…

Synthesis of bi- and tricyclic β-lactam libraries in aqueous medium

2007

Water as a solvent is not only inexpensive and environmentally benign, but may allow good reactivity. The present work focuses on the application of a modified Ugi reaction, i.e. the Ugi four-centre three-component reaction (U-4C-3CR), in aqueous medium to construct β-lactam libraries. All the attempted reactions could be successfully performed in water. The reaction conditions under which the precipitation process was effective were investigated; no further work-up or purification was necessary. In several cases when less water-soluble β-amino acids were used, the precipitated products were isolated easily by simple filtration. In other cases, evaporation of the solvent was appropriate for…

Synthesis of various natural 8,12-elemanolides from artemisin

1989

Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.

Struktur-Wirkungsbeziehungen bei Histaminanaloga, 14. Mitt. 4-Aminomethyl-benzimidazole und 9-Amino-naphth[1,2-d]imidazole

1977

Es wird die Darstellung der bicyclischen Histaminanaloga 4-Aminomethyl-benzimidazol (3a) und 4-Aminomethyl-4,5,6,7-tetrahydro-benzimidazol (3b) sowie der tricyclischen Analoga 9-Amino-6,7,8,9-tetrahydro-naphth[1,2-d]imidazol (6b) und 9-Amino-4,5,5a,6,7,8,9,9a-octahydro-naphth[1,2-d]imidazol (6c) beschrieben. 4-(Aminomethyl)benzimidazoles and 9-Aminonaphth[1,2-d]imidazoles Syntheses of the bicyclic histamine analogues 4-(aminomethyl)benzimidazole (3a) and 4-aminomethyl-4,5,6,7-tetrahydrobenzimidazole (3b) and of the tricyclic analogues 9-amino-6,7,8,9-tetrahydronaphth[1,2-d]imidazole (6b) and 9-amino-4,5,5a,6,7,8,9,9a-octahydronaphth[1,2-d]-imidazole (6c) are described.

Synthesis and Unusual NMR-Spectroscopic Behavior of a Strained Bicyclic Ammonium Salt

2018

Elektrocarboxylierung organischer Chloride mit Zehrandon

1984

Carboxylation par CO 2 de chloro-1 propane, -butane, α-chlorotoluene, dichlorobenzene, chloro-1 naphtalene et chloro-1p ethylbenzene en presence d'une anode de Al dans DMF-bromure de tetrabutylammonium

ChemInform Abstract: Cryptand-Like Anion Receptors

2010

The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…

Total synthesis of the monoterpenes (−)-mintlactone and (+)-isomintlactone

1992

Abstract The first total stereodirected synthesis of the monoterpenes (−)-mintlactone and (+)-isomintlactone from the same chiral starting product is described. A stereoselective, radical-mediated ring closure was the key step in both syntheses.

Cryptand-like anion receptors

2010

The design of supramolecular hosts for anions began with simple diaza bicycles, named katapinands, and has evolved over the last 40 years to a number of elegantly designed receptors capable of binding many different anions. About the same time the term cryptand appeared in reference to another bicyclic compound that was selective for alkaline-earth ions. Since the first report these simple bicycles, a vast arena of hosts has appeared, including acyclic, monocyclic, and other multicyclic supramolecular receptors. Studies of these systems have revealed considerable information about anion coordination chemistry, including the fact that many of these complexes mimic their transition-metal coro…

Cycloaddition reactions of benzothiete and hetero dienophiles for the synthesis of heterocyclic systems

1986

Abstract Benzothiete ( 1 ) undergoes cycloaddition reactions with hetero dienophiles with NN-, NO- or CO- double bonds, leading to six-membered heterocyclic ring systems of 2H-3,4-dihydro-1,2,3-benzothiadiazine ( 3 ), 4H-3,1,2-benzoxathiazine ( 4 ) and 4H-3,1-benzoxathiin.