Inexpensive multigram-scale synthesis of cyclic enamines and 3-N spirocyclopropyl systems

2018 ◽  
Vol 16 (4) ◽  
pp. 652-656 ◽  
Author(s):  
Pratik Kumar ◽  
Omar Zainul ◽  
Scott T. Laughlin
Keyword(s):  
Ring System ◽  
Protecting Groups ◽  
Double Bonds ◽  
Pharmacological Targets ◽  
System P

Cyclic enamines are important synthons for many synthetic and pharmacological targets. We report a method for the synthesis of cyclic enamines with exocyclic double bonds and four- to seven-membered rings that permits usage of common N-protecting groups and tolerates functionality round the ring system.

Direct N-acylation of sulfoximines with carboxylic acids catalyzed by the B3NO2 heterocycle

2017 ◽  
Vol 53 (54) ◽  
pp. 7447-7450 ◽  
Author(s):  
Hidetoshi Noda ◽  
Yasuko Asada ◽  
Masakatsu Shibasaki ◽  
Naoya Kumagai
Keyword(s):  
Carboxylic Acids ◽  
Ring System ◽  
System P

Dehydrative coupling of sulfoximines and carboxylic acids is rendered catalytic by a heterocyclic catalyst featuring the B3NO2 ring system.

Synthesis, computational, and spectroscopic analysis of tunable highly fluorescent BN-1,2-azaborine derivatives containing the N-BOH moiety

2017 ◽  
Vol 15 (48) ◽  
pp. 10172-10183 ◽  
Author(s):  
Carl Jacky Saint-Louis ◽  
Renée N. Shavnore ◽  
Caleb D. C. McClinton ◽  
Julie A. Wilson ◽  
Lacey L. Magill ◽  
...  
Keyword(s):  
Electron Donor ◽  
Spectroscopic Analysis ◽  
Ring System ◽  
Quantum Yields ◽  
System P ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor

Methods to tune the luminescence wavelength and the quantum yields by controlling the power and location of electron-donor and acceptor substituents on the ring system.

scholarly journals Trimerisation of carbon suboxide at a di-titanium centre to form a pyrone ring system

2018 ◽  
Vol 9 (22) ◽  
pp. 5008-5014 ◽  
Author(s):  
Nikolaos Tsoureas ◽  
Jennifer C. Green ◽  
F. Geoffrey N. Cloke ◽  
Horst Puschmann ◽  
S. Mark Roe ◽  
...  
Keyword(s):  
Ring System ◽  
Carbon Suboxide ◽  
Pyrone Ring ◽  
System P

Bis(pentalene)dititanium Ti2(μ:η5,η5-Pn†)2 trimerises carbon suboxide (OCCCO) to form [{Ti2(μ:η5,η5-Pn†)2}{μ-C9O6}], which contains a 4-pyrone core, via the monoadduct [Ti2(μ:η5,η5-Pn†)2 (η2-C3O2)].

Selective Synthesis of exo-Spiro[2′,2′-difluorocyclopropane-3′,2′-tropanes]

Synthesis ◽  
2020 ◽  
Vol 52 (07) ◽  
pp. 1015-1024
Author(s):  
Andrii Gerasov ◽  
Grygoriy A. Dolgonos ◽  
Aleksandr Yu. Mandzhulo ◽  
Alexey Ryabitsky ◽  
Volodymyr Fetyukhin ◽  
...  
Keyword(s):  
Activation Barrier ◽  
Protecting Groups ◽  
Selective Synthesis ◽  
Double Bonds ◽  
Lower Activation ◽  
Conformationally Restrained

Conformationally restrained exo-isomers of N-Boc-protected spiro[2′,2′-difluorocyclopropane-3′,2′-tropanes] were synthesized in 62–83% yield via absolutely diastereoselective cycloaddition of CF2, generated in situ from Me3SiCF3/NaI in refluxing THF, to double bonds of 3-alkylidenetropanes. Standard removal of Boc protecting groups afforded corresponding exo-spiro[2′,2′-difluorocyclopropane-3′,2′-tropane] hydrochlorides in 82–94% yields. DFT and CCSD(T) calculations revealed that the observed exo-selectivity of difluorocarbene addition is likely to be caused by a lower activation barrier of the exo-difluorocyclopropanation compared to the endo-reaction.

A general synthesis of 5,7-diaminoimidazo[4,5-b]pyridine ribosides ("2-amino-1-deazaadenosines") from 5-amino-4-imidazolecarboxamide riboside (AICA riboside)

1992 ◽  
Vol 70 (5) ◽  
pp. 1288-1295 ◽  
Author(s):  
John E. Francis ◽  
Michael A. Moskal
Keyword(s):  
Pyridine Ring ◽  
Sodium Hydride ◽  
Ring System ◽  
Ring Closure ◽  
Protecting Groups ◽  
Amino Group ◽  
Phosphoryl Chloride ◽  
Compound A ◽  
General Synthesis ◽  
Methyl Analog

A short general synthesis of 5-substituted 5,7-diaminoimidazo[4,5-b]pyridines from 5-amino-4-imidazolecarboxamide riboside (AICA riboside) was designed to prepare isosteres of substituted 2-aminoadenosines that are selective adenosine A2 receptor agonists. AICA riboside was converted to a hydroxyl-protected 5-amino-4-imidazolecarbonitrile riboside and reacted with an N,N-disubstituted acetamide in the presence of phosphoryl chloride. Sodium hydride treatment completed the ring closure and introduced the 7-amino group. The hydroxyl protecting groups were removed under standard conditions. N-Substitution of the acetamide by one benzyl moiety led to a 5-N-substituted derivative through hydrogenolysis whereas N,N-dibenzylacetamide led to the 5,7-diamino compound. A 6-methyl analog was obtained from an N,N-disubstituted propionamide. This synthesis may be adapted to other heterocyclic systems, as illustrated by the preparation of an example of the imidazo[4,5-b]pyrrolo[3,2-e]pyridine ring system.

Practical synthesis and cytotoxic evaluation of the pyrazino[1,2-b]-isoquinoline ring system

2016 ◽  
Vol 14 (21) ◽  
pp. 4875-4884 ◽  
Author(s):  
Eduardo Hernández-Vázquez ◽  
Luis D. Miranda
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Cancer Cell Lines ◽  
Ring System ◽  
System P ◽  
Practical Synthesis

A multicomponent three-step synthesis of pyrazino[1-2b]isoquinolines is described. A preliminary cytotoxic screening against cancer cell lines was performed.

A missing member of conjugated N-heterocycles: realizing pyrido[1,2-α]azepine by reacting ruthenium alkenylcarbene complex with alkyne

2018 ◽  
Vol 54 (32) ◽  
pp. 4009-4012 ◽  
Author(s):  
Xiaoxi Zhou ◽  
Fanping Huang ◽  
Chun Tang ◽  
Qingde Zhuo ◽  
Zhixin Chen ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Ring System ◽  
Synthesis And Characterization ◽  
System P

The first successful chemical synthesis and characterization of a bicyclic pyrido[1,2-α]azepine ring system.

A new approach to the 8b-azaacenaphthylene ring system

2015 ◽  
Vol 13 (38) ◽  
pp. 9834-9843 ◽  
Author(s):  
Anushree Kamath ◽  
Charles-Henry Fabritius ◽  
Christian Philouze ◽  
Philippe Delair
Keyword(s):  
Ring System ◽  
New Approach ◽  
System P

A new approach to the 8b-azaacenaphthylene ring system is described featuring several stereoselective transformations.

Cytorhizophins A and B, benzophenone-hemiterpene adducts from the endophytic fungus Cytospora rhizophorae

2019 ◽  
Vol 6 (5) ◽  
pp. 591-596 ◽  
Author(s):  
Hongxin Liu ◽  
Haibo Tan ◽  
Wenxuan Wang ◽  
Wenge Zhang ◽  
Yuchan Chen ◽  
...  
Keyword(s):  
Endophytic Fungus ◽  
Ring System ◽  
System P ◽  
Fused Ring ◽  
Fused Ring System

(±)-Cytorhizophin A and cytorhizophin B (2), novel benzophenone-hemiterpene conjugated hetero-dimers featuring an unprecedented 6/7/6/7 tetracyclic fused ring system.

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