Intramolecular Cyclization of Some Acyclic Nucleoside Analogs

1996 ◽  
Vol 61 (3) ◽  
pp. 442-457 ◽  
Author(s):  
Zlatko Janeba ◽  
Antonín Holý ◽  
Hana Votavová ◽  
Milena Masojídková
Keyword(s):  
Intramolecular Cyclization ◽  
Aqueous Ammonia ◽  
Sodium Hydride ◽  
Nucleoside Analogs ◽  
Oxidative Cyclization ◽  
Membered Ring ◽  
Optically Active ◽  
Cd Spectra ◽  
Acyclic Nucleoside ◽  
Derivatives Of

Reaction of stereoisomeric 8-bromo-9-(2,3-O-isopropylidene-2,3,4-trihydroxybutyl)adenines (8) with concentrated aqueous ammonia, sodium hydride, potassium tert-butoxide, or 1,8-diazabicyclo[5,4,0]undec-7-ene afforded 4e-O,8-anhydro-9-(2,3-O-isopropylidene-2,3,4-trihydroxybutyl)adenines 9 (derivatives of 1,3-oxazepino[2,3-e]adenine). The CD spectra of optically active stereoisomers of 9 have been studied and it was found that for threo isomers 9a and 9b their character corresponds to 5'-O,8-cycloadenosine. The compounds 9 were also prepared by oxidative cyclization of 9-(2,3-O-isopropylidene-2,3,4-trihydroxybutyl)adenines (7) with lead(IV) acetate in benzene. Reaction of 9-(4-hydroxybutyl)adenine (14) with lead(IV) acetate smoothly afforded the seven-membered ring derivative, 4'-O,8-anhydro-9-(4-hydroxybutyl)adenine (15); no anhydro products with five-, six-, and eight-membered ring were found. 2',3'-O-Isopropylideneinosine (16) reacted with lead(IV) acetate to give 5'-O,8-cyclo-2',3'-O-isopropylideneinosine (17) whereas 9-(4-hydroxybutyl)hypoxanthine (18) afforded no cyclic products.

Stereoselective and enantioselective synthesis of five-membered rings via conjugate additions of allylsulfone carbanions

2000 ◽  
Vol 72 (9) ◽  
pp. 1671-1683 ◽  
Author(s):  
Alfred Hassner ◽  
Eugene Ghera ◽  
Tamar Yechezkel ◽  
Victoria Kleiman ◽  
Thiagarajan Balasubramanian ◽  
...  
Keyword(s):  
Membered Ring ◽  
Optically Active ◽  
Enantioselective Synthesis ◽  
Ring Closure ◽  
Chiral Auxiliary ◽  
Asymmetric Induction ◽  
Conjugate Additions ◽  
Derivatives Of ◽  
The Michael Addition ◽  
High Stereoselectivity

This lecture describes some of our studies of lithio derivatives of allyl sulfone carbanions which add α-regioselectively as well as anti diastereoselectively to Michael acceptor olefins. This can be ascribed to chelation in the Michael addition step. When the reaction leads to subsequent ring closure by using a bromoallyl sulfone, the latter acts as a methylenemethane synthon in a (3+2) Michael-initiated ring closure, affording highly functionalized cyclopentane derivatives. Such additions proceed with high stereoselectivity and with asymmetric induction leading to nonracemic substituted cyclopentanones. Additions of allyl sulfone carbanions also proceed stereoselectively to C=N systems containing a chiral auxiliary on N. These can be used in the synthesis of optically active five- and six-membered ring N-heterocycles. Furthermore, chiral groups on the allyl sulfone moiety can induce significant remote asymmetric induction, made possible by the presence of an aromatic π-system which promotes intramolecular chelation to the Li cation.

Therapeutic Journey of 5-Pyrazolones as a Versatile Scaffold: A Review

2021 ◽  
Vol 21 ◽  
Author(s):  
Ravinder Sharma ◽  
Pooja A. Chawla ◽  
Viney Chawla ◽  
Rajeev Verma ◽  
Nandita Nawal ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Protease Inhibitor ◽  
Medicinal Chemistry ◽  
Membered Ring ◽  
Present Review ◽  
Biological Profile ◽  
3C Protease ◽  
Structure Activity ◽  
Derivatives Of ◽  
Heterocyclic Moiety

Abstract: A sizeable proportion of currently marketed drugs come from heterocycles. The heterocyclic moiety 5-pyrazolone is well known five membered ring containing nitrogen. Derivatives of this wonder nucleus have exhibited activities as diverse as antimicrobial, anti-inflammatory, analgesic, antidepressant, anticonvulsant, antidiabetic, antihyperlipidemic, antiviral, antitubercular, antioxidant, anticancer and antiviral including action against severe acute respiratory syndrome (SARS) or 3C protease inhibitor. A number of drugs based on this motif have already made it to the market. Standard texts and literature on medicinal chemistry cite different approaches for the synthesis of 5-pyrazolones. The present review provides an insight view to 5-pyrazolone synthesis, their biological profile and structure activity relationship studies.

New 2-Alkynyl Derivatives of the Acyclic Nucleoside 9-(2,3-Dihydroxypropyl)adenine and Their 6-Guanidinopurine Counterparts as Potential Effectors of Adenosine Receptors

2003 ◽  
Vol 68 (11) ◽  
pp. 2201-2218 ◽  
Author(s):  
Michal Česnek ◽  
Antonín Holý ◽  
Milena Masojídková
Keyword(s):  
Adenosine Receptors ◽  
Sonogashira Coupling ◽  
Acyclic Nucleoside ◽  
Derivatives Of

A series of the new 2-alkynyl derivatives of the acyclic nucleoside 9-(2,3-dihydroxypropyl)- adenine and their 6-guanidinopurine analogues were prepared by the Sonogashira coupling. The effect of the prepared compounds on A1 and A2A receptors was examined.

Novel optically active organometallic derivatives of fullerenes with non-central types of chirality in addends: synthetic and CD studies

2009 ◽  
Vol 50 (38) ◽  
pp. 5347-5350 ◽  
Author(s):  
Viatcheslav I. Sokolov ◽  
Vasily V. Bashilov ◽  
Fedor M. Dolgushin ◽  
Natalya V. Abramova ◽  
Kyrill K. Babievsky ◽  
...  
Keyword(s):  
Optically Active ◽  
Cd Studies ◽  
Derivatives Of

Synthesis and Biological Effects of N-(2-Phosphonomethoxyethyl) Derivatives of Deazapurine Bases

1993 ◽  
Vol 58 (6) ◽  
pp. 1419-1429 ◽  
Author(s):  
Hana Dvořáková ◽  
Antonín Holý
Keyword(s):  
Biological Effects ◽  
Sodium Hydride ◽  
Cesium Carbonate ◽  
Cytostatic Effect ◽  
Phosphonic Acids ◽  
Dna Viruses ◽  
Purine Bases ◽  
Heterocyclic Bases ◽  
L 1210 Leukemia ◽  
Derivatives Of

Analogs of antiviral 9-(2-phosphonomethoxyethyl)adenine (PMEA,II), containing modified purine bases 1-deazaadenine (VII, 3-deazapurine (XI), 7-deaza-7-cyanoadenine (XIIIb) and 3-deazaguanine (XXIb) were prepared by alkylation of the heterocyclic bases with bis(2-propyl) 2-chloroethoxymethylphosphonate (V) in dimethylformamide in the presence of sodium hydride or cesium carbonate. The obtained protected derivatives were deblocked with bromotrimethylsilane to give the phosphonic acids. 3-DeazaPMEG (XXIb) is active against DNA viruses and exhibits a marked cytostatic effect against L-1210 leukemia.

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