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2nd October 2012 @ 11:05
Synthesis of 1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylic acid ( SBBH-1-24) via hydrolysis of ethyl 1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carboxylate (SBBH-1-11).




Reaction Time: 4-09-12 7:15 PM (IST)
Experimental Procedure: The crude product SBBH-1-11 (0.652g, 2.49 mmol, 1 equiv), was dissolved in EtOH: H2O (15:15 mL) and added to an excess of 20% aq. sodium hydroxide (30 mL). The mixture was stirred at rt for 10 min before being heated to 80 °C and left overnight. Next day morning at 9.30 AM (IST) TLC was checked and quite amount of starting material (SBBH-1-11) was found to be present in the reaction mixture. Then solid NaOH (0.498 g, 12.45 mmol, 5 equiv) was added to the reaction mixture and refluxing was continued. After 3 hour further TLC was checked and it was indicated that reaction was complete. The reaction mixture was cooled to room temperature, EtOH was evaporated under reduced pressure and the mixture acidified with dilute HCl (0.5 N, 50 mL) and checked with universal indicator papers (pH 2). Then the reaction mixture was extracted with EtOAc (2 × 25 mL) and washed with brine solution (30 mL). The organic layer was dried over anhyd. Na2SO4 and evaporated under reduced pressure obtained desired product as off-white solid (0.528 g, 90.9%).
Attached Files
2nd May 2012 @ 08:27
Synthesis of (5Z)-5-((1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrol-3-yl)methylene)-2-(phenylimino)thiazolidin-4-one or it’s isomers ( SBBH-1-22) via condensation of 2-(phenylimino)thiazolidin-4-one (SBBH-1-12) and 1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carbaldehyde (SBBH-1-14)





Reaction Time: 16-03-2012 (11.45 IST)

Experimental Procedure: To a stirred solution of 2-(phenylimino)thiazolidin-4-one (SBBH-1-12) (0.067g, 1 equiv, 0.35 mmol) in ethanol (8 mL), piperidine (51µL, 1.5 equiv, 0.525 mmol) was added in 50 mL round bottom flask and the flask was heated at 700 C in an oil bath. Thereafter ethanolic solution of SBBH-1-14 (0.077g, 1 equiv, 0.35 mmol) was added drop wise to the reaction mixture. TLC was monitored after 4 h and the reaction was found to be incomplete. After 8 h further TLC was checked which showed the presence of minor amount of starting materials. At this stage the hot reaction mixture was poured in ice resulting in a yellow colored emulsion which was left over night. Next day morning yellow solid compound was present in the beaker. The excess solution was decanted and the solid compound was filtered, washed with water and dried (0.103g, 75.26%). As the TLC of the filtrate indicated the presence of the product, it was extracted with EtOAc (20 mL), the organic layer separated and dried over Na2SO4 to obtain a residue which was subjected to recrystallization in hot ethanol but with no success.
Attached Files
30th April 2012 @ 10:12
Condensation of 1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carbaldehyde (SBBH-1-14) with 3-phenyl-2-(phenylimino)thiazolidin-4-one (SBBH-1-7)



Reaction time: 02-04-12 (12.50 IST)
Experimental Procedure: To a stirred solution of 3-phenyl-2-(phenylimino)thiazolidin-4-one (SBBH-1-7) (0.244g, 1 equiv, 0.912 mmol) in ethanol (10 mL), piperidine (135µL, 1.5 equiv, 0.1.36 mmol) was added. The mixture solution was transferred to oil bath at 60 oC. SBBH-1-7 was not dissolved properly in ethanol. After 40 minutes of heating SBBH-1-7 almost dissolved after which ethanolic solution of 1-(2-fluorophenyl)-2,5-dimethyl-1H-pyrrole-3-carbaldehyde (SBBH-1-11) was added drop wise. Instantly colourless solution turned into deep yellow coloured solution. First TLC was checked after 1.5 h. of starting the reaction wherein a new less polar spot was observed just above the starting materials. The product spots were visualized in UV and developed under I2 vapours. After 4.5 h TLC was checked again and it suggested that reaction was complete. The hot ethanolic reaction mixture was poured into ice instantly resulting in yellow coloured solid precipitate which was filtered through Buchner funnel and washed with little amount of ethanol and water (20 mL). The yellow solid compound was dried under vacuum over P2O5. After drying of compound (0.389 g, 83.22%) turned to turmeric yellow colour.
Attached Files
24th April 2012 @ 13:27
Synthesis of 2,5-dimethyl-1-(5-methylpyridin-2-yl)-1H-pyrrole-3-carbaldehyde (SBBH-1-18) via reduction of ethyl 2,5-dimethyl-1-(5-methylpyridin-2-yl)-1H-pyrrole-3-carboxylate (SBBH-1-16) and subsequent oxidation of (2,5-dimethyl-1-(5-methylpyridin-2-yl)-1H-pyrrol-3-yl)methanol




Reaction Time: 10-04-12 2:00 PM (IST)

Experimental Procedure: To a stirred ice-cool solution of ethyl 2,5-dimethyl-1-(5-methylpyridin-2-yl)-1H-pyrrole-3-carboxylate (SBBH-1-16) (2.163 g, 8.34 mmol, 1 equiv) in THF (35 mL) in a 100 mL flask fitted with guard tube was added LiAlH4 (0.382 g, 10.06 mmol, 1.2 equiv) portion wise. After addition of LiAlH4 the colour of the reaction mixture changed from yellow to steel black. The reaction mixture was brought to room temperature. After 3 h, as not much progress in the reaction was observed, the reaction mixture was left stirring at room temperature overnight. Next day morning the TLC showed completion of the reaction. Thereafter 2 mL saturated solution of sodium tartrate was added to the reaction mixture to quench excess LiAlH4. The reaction mixture become colloidal solution which was filtered through a Celite bed and washed with THF (40 mL). The filtrate which was collected displayed the presence of two more spots on TLC. The filtrate was concentrated under pressure to give 1.432 g of crude.

Reaction Time: 11-04-12 2.30 PM (IST)

Experimental Procedure: To the crude product (1.432 g, 1 equiv) weighed in 50 mL round bottom flask fitted with a guard tube, 10 mL dry DCM was added. Then activated MnO2 (7.206 g, 10 equiv) was quickly weighed and added to the mixture as solution turned steel black. The reaction was allowed to continue at room temperature and after 1.5 h first TLC was checked which indicated formation of a new spot but the reaction mixture was left stirring overnight at room temperature. Next day morning TLC was checked which indicated that the reaction was complete. The reaction mixture was filtered through a Celite bed and washed with DCM (40 mL) and the filtrate was evaporated under reduced pressure to afford a blackish gum type product. The crude compound was purified via column chromatography on silica gel (100-200 mesh) using 5-6: 95-94 % ethyl acetate and hexane as eluent. After concentrating the desired fractions 0.955 g of product was isolated but it was observed that minor impurities were present.

TLC after 24 hour (40% ethyl acetate in hexane) visualised using UV and I2:
SBBH-1-18 after MnO2 oxidation.jpg
Attached Files
31st March 2012 @ 06:15
Synthesis of ethyl 2,5-dimethyl-1-(5-methylpyridin-2-yl)-1H-pyrrole-3-carboxylate (SBBH-1-16) via condensation of 5-methylpyridin-2-amine with ethyl 2-acetyl-4-oxopentanoate



Reaction Time: 23-03-12 (10.30 IST)
Experimental procedure: Ethyl 2-acetyl-4-oxopentanoate (SBBH-1-1) (3.0 g, 16.12 mmol, 1 equiv.) and solid 5-methylpyridin-2-amine (2.09 g, 19.35 mmol, 1.2 equiv) were mixed in a 50 mL round bottom flask and heated in an oil bath at 90 oC under stirring. After 2 h TLC analysis indicated incomplete reaction. After 7 h, the TLC showed that the reaction was still incomplete and therefore it was continued overnight. Next day in the morning TLC was checked which suggested that the reaction was complete. The reaction mixture was allowed to cool to room temperature. This reaction mixture was observed to be a blackish yellow oil. The mixture was extracted with EtOAc (2× 30 ml) and water (35 mL) and the organic layer was washed with 10% citric acid (20 mL), water: brine (1:1) (2×20 mL). The collected organic layer was dried (Na2SO4) and concentrated under reduced pressure resulting in a dark yellow oil. The oil was purified via column chromatography on silica gel (60-120 mesh) using EtOAc/ hexane (3:97 to 4:96 v/v) as the eluent. The pure fractions were combined and evaporated under reduced pressure to afford the pure product as yellow oil (2.632 g, 52.72%) after sometime yellow oil became white solid.

TLC after 24 hour (40% ethyl acetate in hexane) visualised using UV and I2:
SBBH-1-16 after 24 hr.jpg


1H NMR:
SBBH-1-16 (1H).pdf
Attached Files