DD246996A1 - PROCESS FOR PREPARING, IF NECESSARY, SUBSTITUTED 2-ALKOXY-BZW. 2-aroxy-3,1-benzoxazin-4-ones - Google Patents

Abstract

The invention relates to a process for the preparation of optionally substituted 2-alkoxy- or 2-aroxy-3,1-benzoxazin-4-ones. It is the object of the invention to easily prepare these compounds in high yield by one-step synthesis. The task is to find a technically applicable synthetic route. The object is achieved by the reaction of optionally substituted 2-aminobenzoic acids with Chlorameisensaeurealkyl-, -aralkyl- or -arylestern preferably in pyridine. The compounds obtained are biologically active, they have z. B. chymotrypsininhibierende properties and are also due to their fungicidal and herbicidal properties of interest.

Description

wherein Rn may be the same or different and one or more Η-atoms and / or other substituents such as alkyl, alkoxy, aralkyl, aryl, thioxyanato, mercapto, alkylthio, halogen or nitro, by reaction with type III chloroformates,

CICOOR ² - III

wherein R ^{2 represents} an alkyl, aralkyl, or aryl substituent, in pyridine or substituted pyridine derivatives to the optionally substituted 2-alkoxy or 2-aroxy-3,1-benzoxazin-4-ones of type I.

• I ·

ι : ^ 2 "- ^or2

^R ni I O

be implemented, wherein R _n and R ^{2 have} the meanings given above.

With the given reaction, a synthesis route was found which, starting from the corresponding o-aminobenzolic acid until the preparation of the corresponding 2-alkoxy- or 2-aroxy-3,1-benzoxazin-4-one requires only one stage of synthesis. In the reaction of the corresponding o-aminobenzoic acid with chloroformate in the cold pyridine serves both as a solvent and as a condensing agent. In addition to the described 2-ethoxy-3,1-benzoxazin-4-one, this novel route leads in a simple manner to a series of new and variously substituted 2-alkoxy- or 2-aroxy-3,1-benzoxazin-4-ones higher yields from simple, commercial Reakta'nden.

Embodiments.

The invention will be explained in more detail below by exemplary embodiments. ·

example 1

2-ethoxy-3,1-benzoxazin-4-one

I; R _n = H; R ² = C ₂ H ₅ .

1.4 g (10 mmol) of anthranilic acid are dissolved in 10 μl of abs. Pyridine dissolved. With ice cooling and stirring, 1.7 g (15 mmol) of ethyl chloroformate are added dropwise to this solution. The reaction solution is added with stirring to plenty of water. The precipitate is filtered off, washed with water and recrystallized from ethanol after drying.

M.p .: 91-93 ⁰ C (Lit. mp 90-92 ⁰ C;. Ecsery et al Hung.Teljes 15,850.). Out: 73%

Example 2

2-ethoxy-6-thiocyanato-3,1-benzoxazin-4-one

I; R 1 = 6-SCN R ² = C ₂ H ₅

2.4 g (12.5 mmol) of 2-amino-5-thiocyanato-benzoic acid in the cold in 25 ml abs. Pyridine dissolved. 1.7 g (15 mmol) of ethyl chloroformate are added dropwise with stirring and ice cooling to this solution. After standing overnight, the reaction solution is added with stirring to plenty of water. The precipitate is washed with water, recrystallized from ethanol / water 3: 1 and concentrated i.V. dried.

Size: 67 ° CAus: 85%

Example 3

2-benzyloxy-6,7-dimethoxy-3,1-benzoxazin-4-one

I; R _n = 6-OCH ₃ , 7-OCH ₃ ; R ² = CH ₂ C ₆ H ₅

To a solution of 2.0 g (10 mmol) of 2-amino-4,5-dimethoxy-benzoic acid in 20 ml abs. Pyridine are added dropwise with stirring and ice cooling very slowly 2.55 g (15 mmol) of benzyl chloroformate. While stirring, the reaction solution is poured into plenty of water. The precipitate is washed with water, recrystallized from ethanol and dried in air.

M.p .: 176-178 ° C. Y. 61%

Example 4

I; R _n = 6-OCH ₃ , 7-OCH ₃ ; R ² = C ₆ H ₅ '

To a solution of 2.0 g (10 mmol) of 2-amino-4,5-dimethoxybenzoic acid in 20 ml abs. Pyridine are added dropwise with stirring and ice cooling very slowly 1.7 g (11 mmol) of phenyl chloroformate. Subsequently, the reaction solution is added under stirring and ice cooling in plenty of water. The precipitate is washed neutral with water and recrystallized from ethanol after drying in air.

Mp .: 158-160 ° C. Yield: 47%

Claims (2)

Claim for the invention: '. A process for the preparation of optionally substituted 2-alkoxy- or 2-Aroxy-3,1-benzoxazin-4-ones of the general formula I, characterized in that 2-amino-benzoic acids of the general formula II R ¹ Ti COOH with chloroformates of the general formula III CICOOR ² . , III at room temperature, optionally also with cooling in a solvent such as abs. Pyridine or the like. To the 2-alkoxy- or 2-Aroxy-3,1-benzoxazin-4-ones of the general formula I. ² ' wherein Rj may be the same or different and represent one or more Η-atoms and / or other Su bstituenten such as alkyl, alkoxy, aralkyl, aryl, thiocyanato, mercapto, alkylthio, halogen or nitro and R ^{2 is} an alkyl, aralkyl or aryl , corresponds to be implemented. ',. Field of application of the invention: The invention relates to a process for the preparation of 2-alkoxy- or 2-hydroxy-3,1-benzoxazin-4-ones, which may be substituted on the benzo ring, if appropriate. Such substances can gain importance as biologically active compounds as herbicides and fungicides. Because of their chymotrypsin inhibiting activity, such compounds are still of pharmacological interest. ' Characteristic of the known technical solutions 2-alkoxy- or 2-aroxy-3,1-benzoxazin-4-ones are virtually unknown. Only 2-ethoxy-3,1-benzoxazin-4-one has hitherto been presented in a two-step reaction (Hung.Teljes 15850, ref C.A. 91 39500s [1979], Hung 137.974). In this case, first of anthranilic acid and ethyl chloroformate 2- [N- (ethoxycarbonyl) amino] benzoic acid is formed in 50% yield, which cyclized by the action of dicyclohexylcarbodiimide in dry ethyl acetate or benzene to 2-ethoxy-3,1-benzoxazin-4-one becomes. Object of the invention The aim of the invention is to represent such compounds from easily accessible starting materials in a simple manner in only one synthesis step. Explanation of the essence of the invention The object of the invention is to find a technically applicable synthesis route for the preparation of optionally substituted 2-alkoxy- or 2-aroxy-3,1-benzoxazin-4-ones. According to the invention, this object is achieved in that 2-aminobenzoic acids of type II, COOH