scholarly journals Tuning efficiency of the 4-exo-trig cyclization by the electronic effect: ring closure of 3,3-difluoro-4-pentenyl carbon radicals and synthesis of a gem-difluorocyclobutane nucleoside

2012 ◽  
Vol 48 (89) ◽  
pp. 10993 ◽  
Author(s):  
Hiroki Kumamoto ◽  
Sachiko Kawahigashi ◽  
Hiromi Wakabayashi ◽  
Tomohiko Nakano ◽  
Tomoko Miyaike ◽  
...  
Keyword(s):  
Electronic Effect ◽  
Ring Closure ◽  
Carbon Radicals ◽  
Effect Ring

Formation and Reactions of (1-Chloroalkyl)carbamoyl Chlorides. Synthesis of 1,2,4-Triazolidine-5-ones

1973 ◽  
Vol 51 (3) ◽  
pp. 333-337 ◽  
Author(s):  
Kinko Koyano ◽  
Colin R. McArthur
Keyword(s):  
Ring Closure ◽  
Convenient Synthesis ◽  
Effect Ring ◽  
Substituted Hydrazines ◽  
Nitrogen Bond

N-(α-Chlorobenzyl)carbaniloyl chloride and (α-chlorobenzyl)methylcarbamoyl chloride are formed by reaction of phosgene with N-benzylideneaniline and N-benzylidenemethylamine, respectively. Reaction of these carbamoyl chlorides with a number of nucleophiles is described, some of which cause cleavage of the benzyl to nitrogen bond while others give rise to substitution products without such cleavage. Of the latter type, substituted hydrazines react to effect ring closure to1,2,4-triazolidine-5-ones. The method serves as a convenient synthesis of these new heterocyclic systems.

Stereospecific reactions of cis- and trans-3-Aminochroman-4-ols

1977 ◽  
Vol 30 (10) ◽  
pp. 2205 ◽  
Author(s):  
BV Lap ◽  
LR Williams
Keyword(s):  
Amino Alcohol ◽  
Nitrous Acid ◽  
Potassium Hydroxide ◽  
Amino Alcohols ◽  
Ring Closure ◽  
Stereospecific Reactions ◽  
Cyclic Amide ◽  
Cis And Trans ◽  
Effect Ring ◽  
Chemical Evidence

Stereospecific reactions of epimeric 3-amino-6-methylchroman-4-ols (1 and 2; R = Me) have provided chemical evidence for their configuration and have led us to reverse the configurations that we had assigned previously to the 6-bromo analogues on the basis of N.M.R. data. ��� The 2-chloro-N-(4-hydroxy-6-methylchroman-3-yl)acetamides (3) and (4) were treated with potassium hydroxide in ethanol in an attempt to effect ring closure. The cis-chloroacetamide (4) gave a cyclic amide (5) while the trans-chloroacetamide (3) reacted with solvent to form the trans-3-ethoxyacetamidochroman-4-ol (6). ��� The configurations of the amino alcohols were confirmed by a study of their reactions with nitrous acid where deamination of the cis-amino alcohol gave the chroman-4-one (9) while the trans-amino alcohol gave a trans-diol (10) by an epoxide intermediate.

Ring Closure Matrix

2015 ◽  
Vol 19 (3) ◽  
pp. 274-281
Author(s):  
Milan Randic ◽  
Marjana Novic ◽  
Dejan Plavsic
Keyword(s):  
Ring Closure

The effects controlling the oxygen basicity in alkoxysilanes (RO)nSi(CH3)4-n. The mutual polarizability effect of alkoxy groups attached to silicon

1979 ◽  
Vol 44 (3) ◽  
pp. 750-755 ◽  
Author(s):  
Josef Pola ◽  
Marie Jakoubková ◽  
Václav Chvalovský
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Electronic Effect ◽  
Linear Regression Analysis ◽  
Effect Of Substituents ◽  
Relative Basicity ◽  
Polarizability Effect ◽  
Alkoxy Groups ◽  
Individual Series

Relative basicity of the oxygen in alkoxysilanes (RO)nSi(CH3)3-n having n = 1-4 and various electrondonating and electronwithdrawing groups R measured as Δν(OH) of phenol due to its interaction with these compounds in CCl4 is shown to be chiefly controlled by the electronic effect of substituents R. Linear regression analysis of the Δν(OH) vs n relatioship for individual series (RO)nSi(CH3)4-n suggests the operation of the polarizability effect of RO groups becoming more important with increasing electronwithdrawing nature of R.

Variable electronic effect of silyl groups attached to oxygen

1978 ◽  
Vol 43 (3) ◽  
pp. 746-752 ◽  
Author(s):  
Josef Pola ◽  
Václav Chvalovský
Keyword(s):  
Electronic Effect ◽  
Silyl Groups

A new heterocyclic ring closure in ferricyanide oxidation of 2,4,6-triphenylpyridinium salts

1983 ◽  
Vol 48 (11) ◽  
pp. 3307-3314 ◽  
Author(s):  
Petr Nesvadba ◽  
Petr Štrop ◽  
Josef Kuthan
Keyword(s):  
Alkaline Solution ◽  
Heterocyclic Ring ◽  
Potassium Ferricyanide ◽  
Probable Mechanism ◽  
Ring Closure ◽  
Pyridinium Salts ◽  
Mechanism Of Formation ◽  
Pyrrole Derivatives ◽  
Quaternary Pyridinium Salts ◽  
Heterocyclic Derivatives

The quaternary pyridinium salts Ia-Ic react with alkaline solution of potassium ferricyanide to give the condensed heterocyclic derivatives IIIa, b, IV, whereas the salts Id-If give the pyrrole derivatives IIa-IIc under the same conditions. The diaza heterocycle IIIa reacts with methyl iodide to give methoiodide V, whereas by action of bromine it produces two monobromo derivatives VIa, b. The pyrrole derivatives IIa, b give monobromo derivatives IId, e on bromination. A probable mechanism of formation of the heterocyclic derivatives is discussed.

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