CS264995B1 - (E) -1-Phenyl-2-isocyanato-3-bromo-1-propene and process for its preparation - Google Patents

Abstract

The solution concerns the new /E/-l-phenyl--2-isocyanato-3-bromo-l-propene of formula I. Its preparation consists in the fact that /E/--l-phenyl-2-isocyanato-bromo-l-propene of formula XI is treated with N-bromosuccinimide in the environment of a non-polar organic solvent, preferably tetrachloromethane or benzene in the presence of a peroxide substance such as of dibenzoyl peroxide or azo-bis-isobutyronitrile at the boiling temperature of the solvent.

Description

Isocyanates are highly reactive electrophilic agents by means of which the -HN-CO- fragment can be introduced into the organic molecules. The presence of another reactive center in the isocyanate can be utilized in subsequent reactions to prepare heterocyclic compounds. The haloalkyl isocyanates which are frequently used for this purpose can be prepared e.g. by the reaction of haloalkylamines with phosgene or decomposition of the respective acylazides, but also by the radical halogenation of isocyanates (e.g. DE Patent 1 122 058 (1960/1962), Farbf. Bayer; H. Holtschmidt, E. Degener, CA 57, 7 113 (1962)). YG Balon, V. E. Paranyak: Zh., Org. Khim., 12, 522 (1976), ang. 513. RF Merrit: J, Org. Chem., 32, 1633 (1967)).

A literature study has shown that (E) -1-phenyl-2-isocyanato-3-bromo-1-propene has not been prepared to date.

The subject of the invention is (E) -1-phenyl-2-isocyanato-3-bromo-1-propene of formula X

N = C = O

and the way it was prepared.

The essence of the process for the preparation of (E) -1-phenyl-2-isocyanato-3-bromo-1-propene consists in reacting (E) -1-phenyl-2-isocyanato-1-propene of formula II 'N-C-O

with N-bromosuccinimide in a non-polar organic solvent, preferably carbon tetrachloride or benzene in the presence of a peroxide such as dibenzoyl peroxide or azo-bis-isobutyronitrile at the boiling point of the solvent.

Advantages of the process for the preparation of the compound I according to the invention are that the reaction does not add bromine to the C = C double bond.

(E) -1-phenyl-2-isocyanato-3-bromo-1-propene is a new, simple and highly reactive type of N = C = O-white electrophile that readily enters addition-cyclization reactions with amines and hydrazines to form and six-membered heterocycles (e.g., oxazoline and triazine).

The invention is illustrated but not limited by the following examples:

Example 1

A mixture of (E) -1-phenyl-2-isocyanato-1-propene (31.8 g, 0.2 mol), N-bromosuccinimide (35.6 g) and dibenzoyl peroxide (2.42 g, 20 mmol) in carbon tetrachloride (20 ml) was heated. approx. 0.5 h to reflux. After cooling, the precipitated succinimide was aspirated and the carbon tetrachloride was evaporated. The residue was dissolved in hexane and stored for crystallization in a refrigerator at -20 ° C.

Yield 79-84%. T. t. Mp 37-39 ° C.

Example 2

A mixture of 31.8 g (0.2 mol) of (E) -1-phenyl-2-isocyanato-1-propene, 35.6 g (0.2 mol) of N-bromosuccinimide and 1.64 g (10 mmol) of azo of bis-isobutyronitrile was heated in benzene 0.5 h and treated as in Example 1.

Yield 56-63%.

The obtained (E) -1-phenyl-2-isocyanato-3-bromo-1-propene I is a crystalline solid, m.p. t. Mp 37-39 ° C (from hexane).

Summary formula: C ₁₀ H _g BrNO Molecular weight: 237,9

Elemental analysis: % C % H % N Quantity calculated: 50.44 3.36 5.88 Quantity found: 50.41 3.39 5.79

The structure of compound I was demonstrated by IR and ¹ H NMR spectral methods.

_ -i

IR: ν cm (CHCl3) 248248 (N = C = O).

1 H NMR Spectrum: δ, ppm (CDCl 3), 4.20 with 2H (CH ₂ ), 6.13 with 1H (CH), 7.31-7.67 m 5H (H-arom.).

Spectral measurements

Infrared spectra were recorded on a Specord IR 75 spectrophotometer (Carl Zeiss Jena). NMR spectra were recorded on a 80 MHz Tesla BS 487 spectrophotometer.

Claims (2)

(E) -1-phenyl-2-isocyanato-3-bromo-1-propene of formula I N = C = O CH ₂ Br (I) 2. A process for the preparation of (E) -1-phenyl-2-isocyanato-3-bromo-1-propene according to claim 1, characterized in that (E) -1-phenyl-2-isocyanato-1-propene of formula II ( II) treats with N-bromosuccinimide in an environment of a non-polar organic solvent, preferably carbon tetrachloride or benzene in the presence of a peroxide such as dibenzoyl peroxide or azo-bis-isobutyronitrile at the boiling point of the solvent.