Nucleophilic Substitution at Silicon (SN2@Si) via a Central Reaction Barrier

2007 ◽  
Vol 72 (6) ◽  
pp. 2201-2207 ◽  
Author(s):  
A. Patrícia Bento ◽  
F. Matthias Bickelhaupt
Keyword(s):  
Nucleophilic Substitution ◽  
Reaction Barrier ◽  
Central Reaction

The Synthesis of New Selenium-containing Heterocycles by the Oxidation Reaction of 2,4-Diaryltetrahydro-4H-selenochromenes

2020 ◽  
Vol 24 (15) ◽  
pp. 1663-1668
Author(s):  
Dmitriy Yurievich Direnko ◽  
Boris Ivanovich Drevko ◽  
Yaroslav Borisovich Drevko
Keyword(s):  
Nucleophilic Substitution ◽  
Chlorine Atom ◽  
Oxidation Reaction ◽  
Heterocyclic Fragment ◽  
Oxidative Aromatization

We have explored the reactions of tetrahydro-4H-selenochromenes in the presence of phosphoric pentachloride, and synthesized new condensate aroylbenzoselenophenes. During the reactions, tetrahydro-4H-selenochromenes with phosphoric pentachloride underwent oxidative aromatization and nucleophilic substitution for a chlorine atom of one of the protons in the alicyclic fragment. Also, the narrowing of the heterocyclic fragment occurred as in synthesized selenium-containing compounds earlier transformed into the corresponding condensate aroylbenzoselenophenes.

On the Reaction of 2,5-Dihydroxy-[1,4]-benzoquinone with Diamines – Strain-induced Reactivity Effects

2020 ◽  
Vol 24 ◽  
Author(s):  
Hubert Hettegger ◽  
Andreas Hofinger ◽  
Thomas Rosenau
Keyword(s):  
Nucleophilic Substitution ◽  
Product Structure ◽  
Carbonyl Groups ◽  
Reaction Products ◽  
Double Bonds ◽  
Oh Groups ◽  
Natural Geometry ◽  
Quinoid Structure ◽  
Bond Localization

: The regioselectivity of the reaction of 2,5-dihydroxy-[1,4]-benzoquinone (DHBQ) with diamines could not be explained satisfactorily so far. In general, the reaction products can be derived from the tautomeric ortho-quinoid structure of a hypothetical 4,5-dihydroxy-[1,2]-benzoquinone. However, both aromatic and aliphatic 1,2-diamines form in some cases phenazines, formally by diimine formation on the quinoid carbonyl groups, and in other cases the corresponding 1,2- diamino-[1,2]-benzoquinones, by nucleophilic substitution of the OH groups, the regioselectivity apparently not following any discernible pattern. The reactivity was now explained by an adapted theory of strain-induced bond localization (SIBL). Here, the preservation of the "natural" geometry of the two quinoid C–C double bonds (C3=C4 and C5=C6) as well as the N–N distance of the co-reacting diamine are crucial. A decrease of the annulation angle sum (N–C4–C5 + C4–C5–N) is tolerated well and the 4,5-diamino-ortho-quinones, having relatively short N–N spacings are formed. An increase in the angular sum is energetically unfavorable, so that diamines with a larger N–N distance afford the corresponding ortho-quinone imines. Thus, for the reaction of DHBQ with diamines, exact predictions of the regioselectivity, and the resulting product structure, can be made on the basis of simple computations of bond spacings and product geometries.

The preparation of 3-amino-3-deoxy-1,2-O-isopropylidene-α-L-erythrofuranose, 3-amino-3-deoxy-1,2-O-isopropylidene-β-D-threofuranose and their derivatives

1980 ◽  
Vol 45 (12) ◽  
pp. 3378-3390 ◽  
Author(s):  
Jiří Jarý ◽  
Milena Masojídková ◽  
Ivan Kozák ◽  
Miroslav Marek ◽  
Jan Staněk
Keyword(s):  
Nucleophilic Substitution ◽  
Sodium Azide ◽  
Sodium Benzoate ◽  
Nmr Spectra ◽  
Subsequent Reduction ◽  
H Nmr ◽  
Amino Derivatives

The title amino derivatives VI and XIV were prepared by nucleophilic substitution of p-toluenesulfonyl derivatives II and XVII with sodium azide or hydrazine and subsequent reduction. Nucleophilic substitution of compounds II and XVII with sodium benzoate was also investigated. The 1H NMR spectra of the substances prepared are discussed.

Preparation of Chloro and Sulfanyl Derivatives of 1-(2-Deoxy-4-C-hydroxymethyl-α-L-threo-Pentofuranosyl)uracil

1997 ◽  
Vol 62 (7) ◽  
pp. 1114-1127 ◽  
Author(s):  
Hubert Hřebabecký ◽  
Jan Balzarini ◽  
Antonín Holý
Keyword(s):  
Nucleophilic Substitution ◽  
Hydrogen Chloride ◽  
Thionyl Chloride ◽  
Sodium Methoxide ◽  
Thioacetic Acid ◽  
Uracil Derivatives ◽  
Derivatives Of ◽  
Hiv 1

3'-Chloro and 3'-acetylsulfanyl derivatives of 1-(2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil were prepared by reaction of 2,3'-anhydro-1-{5'-O-benzoyl-4'-C-[(benzoyloxy)methyl]-2'-deoxy-α-L-erythro-pentofuranosyl}uracil (3) with hydrogen chloride and thioacetic acid, respectively. The reaction with hydrogen chloride gave a mixture of N-1 and N-3 substituted uracil derivatives 12 and 14. Reaction of 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-α-L-threo-pentofuranosyl}uracil (7) with thionyl chloride and subsequent debenzoylation afforded 1-(4-C-chloromethyl-2-deoxy-β-D-erythro-pentofuranosyl)uracil (19). Nucleophilic substitution with lithium thioacetate, followed by deacylation, converted 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (9) into 1-(2-deoxy-4-C-sulfanylmethyl-β-D-erythro-pentofuranosyl)uracil (21). The obtained thiols were oxidized with iodine or air to give 1,1'-[disulfandiylbis(2,3-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-3,1-diyl]di(pyrimidine-2,4-(1H,3H)-dione) (17) and 1,1'-[disulfandiylbis(2,5-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-5,1-diyl]di(pyrimidine-2,4(1H,3H)-dione) (22). Reaction of 1-{3-acetylsulfanyl-5-O-methanesulfonyl-4-C-[(benzoyloxy)methyl]-2,3-dideoxy-α-L-threo-pentofuranosyl)}uracil (24) with methanolic sodium methoxide afforded 1-(3,5-anhydro-2,3-dideoxy-4-C-hydroxymethyl-3-sulfanyl-α-L-threo-pentofuranosyl)uracil (25). The same reagent was used in the preparation of 1-(3,5-anhydro-2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil (26) from 1-{4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (8). From the series of 4'-substituted 2'-deoxyuridine derivatives, synthesized in this study, solely the 4'-chloromethyl derivative 19 and the oxetane derivative 26 exhibited an appreciable activity against HIV-1 and HIV-2.

Unusual Rearrangement of Naphthalene in the Synthesis of a Novel B8-B8-Bridged Derivative in the [(1,2-C2B9H11)2-3-Co]- Series. X-Ray Structure and 11B NMR Spectra of [8,8'-μ-(CH2-C9H6)-(1,2-C2B9H10)2-3-Co]- (CH3)4N+

1997 ◽  
Vol 62 (5) ◽  
pp. 746-751 ◽  
Author(s):  
Andreas Franken ◽  
Jaromír Plešek ◽  
Christiane Nachtigal
Keyword(s):  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Nucleophilic Substitution ◽  
Nmr Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unusual Rearrangement ◽  
Multinuclear Nmr Spectroscopy ◽  
11B Nmr ◽  
Isolated Compound

On treatment of the [(1,2-C2B9H11)2Co]- ion with naphthalene in presence of AlCl3 a remarkably bridged [8,8'-μ-(CH2-C9H6)-(1,2-C2B9H10)2-3-Co]- ion is obtained as a single isolated compound. The triatomic -CH2-C9H6- bridge is derived from the rearranged naphthalene nucleus. The mechanism of this reaction is obscure but it does resemble the "Electrophile-Induced Nucleophilic Substitution" reported earlier. The structure of the compound was established by multinuclear NMR spectroscopy and by single crystal X-ray diffraction.

Synthesis and Antituberculotic Activity of Some Substituted 3-Arylamino-5-cyano-2-pyrazinecarboxamides

1995 ◽  
Vol 60 (7) ◽  
pp. 1236-1241 ◽  
Author(s):  
Martin Doležal ◽  
Jiří Hartl ◽  
Antonín Lyčka ◽  
Vladimír Buchta ◽  
Želmíra Odlerová
Keyword(s):  
Nucleophilic Substitution ◽  
Elemental Analysis ◽  
Nmr Spectra ◽  
Substituted Anilines ◽  
H Nmr

Nucleophilic substitution of 3-chloro-5-cyano-2-pyrazinecarboxamide by substituted anilines afforded substituted 3-arylamino-5-cyano-2-pyrazinecarboxamides I-X. The structures of compounds were confirmed by elemental analysis, UV, IR and 1H NMR spectra. The assessment of in vitro antimycotic and antimycobacterial activities of the compounds was carried out. The highest antituberculotic activity against M. tuberculosis in this series was shown by 3-anilino- 5-cyano-2-pyrazinecarboxamide (I), whose efficacy was the same as that of pyrazinecarboxamide.

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