Exp115-ii.JPG

Objective

To monitor the synthesis of a Ugi adduct from furfural, methylamine, benzylisocyanide and α,4-dimethylphenylacetic acid by NMR spectroscopy.

Procedure

To a 2.0M solution of methylamine in methanol (250ul, 0.5 mmol) was added methanol-d4 (250uL) and furfural (41.5uL, 0.5 mmol) in an NMR tube. The imine formation was monitored by proton magnetic resonance spectroscopy. After twenty four hours α,4-dimethylphenylacetic acid (82.1mg, 0.5 mmol) and benzylisocyanide (60.5uL, 0.5 mmol) was added to it. The reaction was further monitored.

Results


Furfural
HNMR
CNMR
Methylamine (1.0M Solution in 1:1 CH3OH : CD3OD)
HNMR
α,4-dimethylphenylacetic
HNMR
CNMR
Benzylisocyanide
H NMR
C NMR

Exp115A
t = 5min
t = 7min
t = 4h 56min
t = 24h 39min
Exp115B
t = 8min
t = 18min
t = 29min
t = 43min
t = 1h 3min
t = 2h 32min
t = 23h 53min
t = 48h 10min

Discussion

1. Imine formation was fast (Complete within 5 min). Some imine reversal (how much) was observed upon the addition of acid and isocyanide.
2. After 2 days the reaction is about x% complete, based on the aldehyde peak at 9.5 ppm and isocyanide (CH2 t) at 4.68 ppm.
3. New peaks between 1.36-1.45 (2 doublets) ppm are consistent with the desired product, indicating that there are two NMR recognizable stereochemical configurations (out of 4 possible diasteromers) of the ugi product.

Conclusion


Log

2007-07-26

16:40 Measured out a solution of methylamine (250uL, 2.0M in CH3OH) in an NMR tube
16:45 Added 250uL of CD3OD to the NMR tube containing methylamine (50% CH3OH and 50%CD3OD)
16:47 Added furfural (41.5uL) to the NMR tube to obtain 115A
16:52 Obtained HNMR of 115A (t = 5min)
16:54 Obtained HNMR of 115A (t = 7min)
21:43 Obtained HNMR of 115A (t = 4h 56min)

2007-07-27

17:26 Obtained HNMR of 115A (t = 24h 39min)
17:39 Added α,4-dimethylphenylacetic acid (82.1mg) and benzylisocyanide (60.6uL) in the NMR tube containing 115A, to obtain 115B
17:47 Obtained HNMR of 115B (t = 8min)
17:57 Obtained HNMR of 115B (t = 18min)
18:08 Obtained HNMR of 115B (t = 29min)
18:22 Obtained HNMR of 115B (t= 43min)
18:42 Obtained HNMR of 115B (t = 1h 3min)
20:11 Obtained HNMR of 115B (t = 2h 32min)

2007-07-28

17:32 Obtained HNMR of 115B (t = 23h 53min); the solution in the NMR tube has turned deep brown in color..it does not appear that there is any solid in the tube

2007-07-28

17:57 Obtained HNMR of 115B (t = 48h 10min).. A small amount of a dark (brown/green) precipitate had settled down at the bottom of the tube, which dissolved back upon vigorous shaking.