CS226929B1 - Hydrazides of furo (3,2-b)pyrol-5-carboxylic acids and method of preparing same - Google Patents

Description

SOCIALIST RBPUBLIC DESCRIPTION FOLLOWING COPY QSC 226929 (11) (Bl) (51) Int. Cl »jC07 D 491/048 (13) L (22) Registered 14 06 82 (21) (PV 4382-82) (40) Published 27 05 83 MU PRO VYNAlfCT A OBrtW (45) Published 15 05 86 1751

Author of the Invention KRUTOŠÍKOVÁ ALŽBĚTA doc. CSc., KOVÁČ JAROSLAV prof. CSc., BRATISLAVA, KRÁLOVICOVA EVA, ŠURANY (54) Furo [3,2-b] pyrrole-5-carboxylic acid hydrazides and methods of their preparation

The invention relates to novel furo (3,2-b) pyrrole-5-carboxylic acid hydrazides of the general formula I

acids as starting materials. This reaction was already investigated by Curti et al. [Chem. Ber. 35, 3229 (1902)]. The excess hydrazine hydrate can be suppressed by the formation of N, N-diacylhydrazine, which is produced in the small volume as a by-product of the reaction.

The process for the preparation of furo (3,2-b) -pyrrole-5-carboxylic acid hydrazides of the formula I is based on the (3,2-b) -pyrrole-5-carboxylic acid esters (Cs. Authentic Certificate No. 223 442, Collection by Chem. Commun., 44, 1799, 1979), wherein R is H, phenyl and 4-tolyl and the process for their preparation.

Carboxylic acid hydrazides can be prepared in several ways:

The synthesis of hydrazides by reaction of carboxylic acids with hydrazine is the least suitable method since it requires water to be eliminated from the reaction medium. A disadvantage of the preparation of hydrazides from chlorides and acid anhydrides is that, irrespective of the molar ratio of the two reaction components, diarylhydrazines often tend to be the product. A more preferred method is to prepare the hydrazides using carboxylic esters

where R is as defined above, hydrate the hydrate in methanol or ethanol to boil the solvent. The advantages of preparing the compounds of the invention include, but are not limited to, the fact that 226929 226923 is carried out in undemanding conditions with good yields.

Carboxylic acid hydrazides are widely used as various reaction components in organic synthesis. With nitric acid, they give azides that provide a wide-ranging reaction. They react with acids, acid halides, nitriles and the like. They provide the possibility of preparing various heterocyclic nitrous compounds with two or more nitrogen heteroatoms.

The subject matter of the invention illustrates, but is not limited to, the following: Example

4H-furo (3,2-b) pyrrole-5-carboxylic acid hydrazide (Ia, where R = H)

Ethyl 4H-furo [3,2-b] pyrol-5-carboxylate (1.79 g, 0.01 mol) was dissolved in methanol (200 mL) and 90% hydrazine hydrate ( 3.5 ml). The mixture was heated at reflux for 20 h. Then a portion of the solvent was distilled off (100 mL), the reaction mixture was cooled, and the crystalline material was filtered off. 4H-furo (3,2-b) pyrrole-5-carboxylic acid sahydrazide is obtained in 89% yield. Example 2

Ethyl 4H-uro (3,2-b) pyrrole-5-carboxylate (1.79 g, 0.01 mol) and 90% hydrazine hydrate are added to the mother liquor obtained by filtration of the 4 H -furo- (3) hydrazide. 2-b) pyrrole-5-carboxylic acid. The reaction mixture is heated for 3 h. The procedure is analogous to Example 1. The procedure is identical to Example 1, except that ethanol is used as the methanol. The mixture was heated for 15 h. the mixture is worked up as in Example 1.:. The obtained 4H-furo (3,2-b) -pyrrole-5-carboxylic acid hydrazide Ia is a compound of formula Ia

(ia)

Compound Ia is a crystalline substance, m.p. 225 degrees Celsius (methanol).

Elemental Analysis:

% Calculated: 50.92% C, 4.27% H, 25.45% N;

Found: 50.72% C, 4.23% H, 25.31% N.

The structure of Compound Ia was demonstrated by spectral IR, UV, H-NMR methods: IR: ν max (KBr cm -1): 1623 (C = O) UV: Ama ,; (log ε) (methanol nm): 294 (4.49); 227 (4.00) 1H - NMR (DMSO-d6): 7.66 (1H, d, C (2, H), 6.60 (1H, dd, C (3, -H), 6.82) (1H, d, C (6) -H), I2.3 = 2, J3.6 = 0.8, J4.6 = 1.6.

Similarly, 2-phenyl-4H-furo (3,2-b) pyrrole-5-carboxylic acid hydrazide (Ib) was prepared from ethyl 2-phenyl-4H-furo (3,2-b) pyrrole-5-carboxylate (Ib). ), in 89% yield, of a compound of structural formula Ib

(Ib)

Compound Ib is a live crystalline substance tt. 232 ° C (methanol).

Formula: C13H11N3O2

Molecular Weight: 241,2

Elemental Analysis:

% Calculated: 64.73% C, 4.60% H, 17.42% N;

Found: C, 64.52; H, 4.62; N, 17.30. The structure Ib was confirmed by IR, UV, NMR spectral methods. IR: ν max (KBr cm -1): 1614 (C = O) UV: λm - (loge) (methanol nm): 337 (4.84), 2.33 (3.85), 207 (4.08) Ή-NMR (DMSO-d 6): 7.09 (1H, dd, C (3) -H), 6.85 (1H, dd, C 6) -H), 7.25-7.93 (5H , m, Harom), J3.6 = 0.8.

Formula: C 7 H 7 N 3 O 2 Molecular Weight: 165.1

Claims (2)

226929 Example 5 Similar ethyl 2- (4-tolyl) -4 H -furo- (3,2-b) pyrrole-5-carboxylate 2- (4-tolyl) -4H-f hydrazide was prepared. uro (3,2-b) pyrrole-5-carboxylic acid (Ic) in a yield of 84%, a structural compound of formula Ic Compound Ic is a tt crystalline substance tt 257 ° C (methanol). Formula: C 14 H 13 N 3 O 2 Molecular Weight: 255.2 Elemental Analysis: Calculated: 65.88% o / o C, 5.13% H, 16.16% N; Found: C, 65.68; H, 5.12; N, 16.31. The structure of Ic was determined by spectral methods: IR, UV, Ή-NMR. IR: λ max (KBr cm -1): 1623 (C = O) UV: λ max (loge) (methanol nm): 342 (4.77), 211 (4.11) Ή — NMR (DMSO-d 6): 6 98 (1H, d, C (3) -H), 6.81 (1H, dd, C (6) -H), 11.37 (1H, b, N-H), > 9.31 (1H, b , N — H), 4.37 (2H, b, NH2), 7.56, 7.21 (4H, d, Harom), ,63.6 - θ> 8 · Spectral Measurements Infrared spectra were measured on a spectra-trophotometer! SPECORD 71 Irishman (Carl Zeiss-Je-on). Electron beams were measured on a SPECORD UV VIS spectrophotometer (CaZeiss-Jena) at 200-800 nm at a concentration of 2.105-105 mol-1. Ή-NMR spectra were recorded on a 80 MHz BS 487 C Tesla spectrophotometer. The hexa-methylsilane internal standard was appropriately used. READ OUT 1, Hydro (3,2-b) pyrrole-5-carboxylic acid hydrazides of the general formula I, characterized in that the acid esters of the (3,2-b) pyrrole-5-carboxylic acid of the general formula II are wherein R is H, phenyl, 4-tolyl. 2. A process for preparing (3,2-b) pyrrole-5-carboxylic acid hydrazides according to the above wherein R is as defined above, treating the solvent with hydrazine hydrate in methanol or ethanol.