Exp087.JPG

Objective

To obtain the Boc-deprotected free amine of the ugi product (086B) from Exp086

Procedure

Dissolved 92.8mg (0.202mmol) of the Ugi product 86B from Exp086 in 700uL CDCl3 in an NMR tube. Then 700uL of trifluoroacetic acid was added to the above solution (50% solution in CDCl3). The removal of the boc group was monitored by HNMR. After 10min the solution was transferred in 50mL erlenmeyer flask placed in a dry ice-acetone icebath. Then a saturated NaOH solution (~10ml)) was added to neutralize the acid. A pH of ~11 was obtained .Then dichloromethane (10 mL) was added to it, the brown oily contents were mixed well by squirting. The contents were then transferred to a separatory funnel, mixed well, and the organic layer was separated out. To the aqueous layer dichloromethane (5 mL)was added again to extract the remaining free amine. The organic layers were combined, washed with water (10mL) again and dried using anhydrous MgSO4. The solid MgSO4 was removed by suction filteration and the dry organic layer was then rotovaped / vacuumed to remove the solvent. The product was weighed and analyzed by NMR spectroscopy. Yield - 78%. Add characterization info.

Results

87A
HNMR -500MHz
HNMR -300MHz
CNMR
DEPT
All protonated carbons
Overlay of CNMR and All protonated carbons
FAB
87A' (After TFA addition to 87A)
t = 02min
t = 07min
t = 10min
87B
HNMR- 500MHz
CNMR -500MHz

Discussion

  1. Can the furan/benzylic region (5-6 ppm) be clarified with irradiation experiments?

Conclusion


Log

2007-04-09

14:40 Obtained a HNMR of a solution of 87A (92.8mg) [86B of the previous Exp 086] in 700uL CDCl3.
15:07 Added TFA (700uL) to 87A to obtain 87A'
15:09 Obtained HNMR to 87A', within a few minutes the reaction mixture in the NMR tube turned deep red t = 02min
15:14 Obtained HNMR of 87A' t = 07min
15:17 Obtaind HNMR of 87A' t = 10min
15:18 Poured the solution from the NMR tube in to an erlenmeyer flask, and placed it in dry ice-acetone bath
15:20 Added a saturated solution of NaOH (~10ml) to the erlenmyer flask in dry ice, the solution solidied shortly
15:24 Added another 5ml of NaOH to the TFA / CDCl3 / 87A, mixed the solution my squirting the reaction.
15:35 Added dichloromethane to the now basic (checked with a litmus paper) solution (pH~11) and poured it out into a clean separatory funnel.
15:45 Separated the bottom organic layer from the aqueous layer, washed the aqueous layer again with 5ml dichloromethane.
16:00 Collected the organic layers together and poured them back into the empty sep. funnel and washed it distilled water (10mL), obtained the organic layer and dried it with anhy. MgSO4.
16:30 Set dry organic layer on a rotovap connected to a high vac. to remove the solvent.
18:00 Obtained 56mg of 87B, brown oil.

Tags

87B InChI=1/C20H27N3O3/c1-14-10-11-16(26-14)13-23(17(24)12-21)18(15-8-6-5-7-9-15)19 (25)22-20(2,3)4/h5-11,18H,12-13,21H2,1-4H3,(H,22,25)
TFA InChI=1/C2HF3O2/c3-2(4,5)1(6)7/h(H,6,7)