Neighbouring-group participation by ether oxygen in displacement reactions of 3α-substituted 2β,19-oxide-androstanes

1970 ◽  
Vol 0 (12) ◽  
pp. 770-771 ◽  
Author(s):  
F. Kohen ◽  
G. Adelstein ◽  
R. E. Counsell
Keyword(s):  
Group Participation ◽  
Neighbouring Group Participation ◽  
Displacement Reactions ◽  
Ether Oxygen

scholarly journals Neighbouring Group Participation in the Methanolysis of a Vicinal Diepoxide

1999 ◽  
Vol 23 (6) ◽  
pp. 356-357
Author(s):  
James R. Hanson ◽  
Peter B. Hitchcock ◽  
Ismail Kiran
Keyword(s):  
Hydroxy Group ◽  
Group Participation ◽  
Neighbouring Group Participation

The tetracyanoethylene catalysed methanolysis of 17β-acetoxy-4β,5β:6α,7α-diepoxyandrostane afforded 17β-acetoxy-4α,7α-oxido-5β-hydroxy-6β-methoxyandrostane in which the methanolysis product of the 6α,7α-epoxide has participated in the cleavage of the 4β,5β-epoxide; the reaction is modified however by an adjacent 3β-hydroxy group.

Pyrolysis of aryl azides. II. Naphthyl azides

1972 ◽  
Vol 25 (3) ◽  
pp. 599 ◽  
Author(s):  
G Boshev ◽  
LK Dyall ◽  
PR Sadler
Keyword(s):  
Nitro Group ◽  
Steric Effect ◽  
Kinetic Studies ◽  
Oxidative Cyclization ◽  
Nitrobenzene Solution ◽  
Aryl Azides ◽  
Phenyl Azide ◽  
Group Participation ◽  
Neighbouring Group Participation ◽  
Group Effects

Kinetic studies of the pyrolyses of 1- and 2-naphthyl azides reveal neighbouring group participation by nitro and phenylazo substituents. The acceleration observed in 1-nitro-2-naphthyl azide, 1-phenylazo-2-naphthyl azide, and 2-nitro-1-naphthyl azide is 1730-, 211-, and 23.6-fold, respectively, in nitrobenzene solution at 120�. These effects are all smaller than that of the 2-nitro group in phenyl azide (3370-fold), which is ascribed to the steric effect of the peri hydrogen at C8 in naphthyl azides. The sizes of these neighbouring group effects correlate with the success of oxidative cyclization of ortho-substituted naphthylamines with (diacetoxyiodo)benzene.

scholarly journals Neighbouring group participation in the unblocking of phosphotriesters of nucleic acids

1979 ◽  
Vol 6 (6) ◽  
pp. 2237-2259 ◽  
Author(s):  
J.F.M. de Rooij ◽  
G.Wille Hazeleger ◽  
P.M.J. Burgers ◽  
J.H. van Boom
Keyword(s):  
Nucleic Acids ◽  
Group Participation ◽  
Neighbouring Group Participation

scholarly journals Synthesis and Conformational Analysis of Fluorinated Uridine Analogues Provide Insight into a Neighbouring-Group Participation Mechanism

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5513
Author(s):  
Freideriki Michailidou ◽  
Tomas Lebl ◽  
Alexandra M. Z. Slawin ◽  
Sunil Vishnuprasadji Sharma ◽  
Murray J. B. Brown ◽  
...  
Keyword(s):  
Conformational Analysis ◽  
Antiviral Agents ◽  
Synthetic Methods ◽  
Nucleoside Analogues ◽  
Mechanism Of Formation ◽  
Group Participation ◽  
Enzymatic Function ◽  
Neighbouring Group Participation ◽  
Sn2 Pathway ◽  
Insight Into

Fluorinated nucleoside analogues have attracted much attention as anticancer and antiviral agents and as probes for enzymatic function. However, the lack of direct synthetic methods, especially for 2′,3′-dideoxy-2′,3′-difluoro nucleosides, hamper their practical utility. In order to design more efficient synthetic methods, a better understanding of the conformation and mechanism of formation of these molecules is important. Herein, we report the synthesis and conformational analysis of a 2′,3′-dideoxy-2′,3′-difluoro and a 2′-deoxy-2′-fluoro uridine derivative and provide an insight into the reaction mechanism. We suggest that the transformation most likely diverges from the SN1 or SN2 pathway, but instead operates via a neighbouring-group participation mechanism.

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