Cyclization of Substituted Phenyl N-(2-Hydroxybenzyl)carbamates in Aprotic Solvents. Synthesis of 4H-1,3-Benzoxazin-2(3H)-ones

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Title:Cyclization of Substituted Phenyl N-(2-Hydroxybenzyl)carbamates in Aprotic Solvents. Synthesis of 4H-1,3-Benzoxazin-2(3H)-ones
Creators:
Mindl, Jaromír
Hrabík, Oldřich
Štěrba, Vojeslav
Kaválek, Jaromír
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 65, 8, pp. 1262-1272
Uncontrolled Keywords:Benzoxazines, Cyclizations, Kinetics, Benzoxazinones, Carbamates, Substituent effects

Abstract

The kinetics of cyclization of substituted phenyl <i>N</i>-(2-hydroxybenzyl)carbamates and their <i>N</i>-methyl analogs, prepared by the reaction of 2-(aminomethyl)phenols with substituted phenyl chloroformates, was studied in dioxane or toluene at the temperatures 110-180 °C. Electron-withdrawing substituents in the leaving phenoxy group strongly accelerate the rate&nbsp;of cyclization (ρ = 2.45 ± 0.15) while the substituents in the other ring have virtually no effect. The cyclization was catalyzed with triethylamine in toluene but not in dioxane. On the basis of these results, the most convenient method for preparation of substituted 4<i>H</i>-1,3-benzoxazin-2(3<i>H</i>)-ones was a one-hour reflux of substituted 4-nitrophenyl <i>N</i>-(2-hydroxybenzyl)carbamates in dioxane. Based on the influence of substituents, solvents (dioxane and toluene) and triethylamine, the reaction mechanism and structure of the transition state were proposed. <p>

Title:Cyclization of Substituted Phenyl N-(2-Hydroxybenzyl)carbamates in Aprotic Solvents. Synthesis of 4H-1,3-Benzoxazin-2(3H)-ones
Creators:
Mindl, Jaromír
Hrabík, Oldřich
Štěrba, Vojeslav
Kaválek, Jaromír
Uncontrolled Keywords:Benzoxazines, Cyclizations, Kinetics, Benzoxazinones, Carbamates, Substituent effects
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:65
Number:8
Page Range:pp. 1262-1272
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc20001262UNSPECIFIED
ID Code:1715
Item Type:Article
Deposited On:06 Feb 2009 17:12
Last Modified:06 Feb 2009 16:12

Citation

Mindl, Jaromír; Hrabík, Oldřich; Štěrba, Vojeslav; Kaválek, Jaromír (2000) Cyclization of Substituted Phenyl N-(2-Hydroxybenzyl)carbamates in Aprotic Solvents. Synthesis of 4H-1,3-Benzoxazin-2(3H)-ones. Collection of Czechoslovak Chemical Communications, 65 (8). pp. 1262-1272. ISSN 0010-0765

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