Objective

To study the chemical interaction between N-(tert-butoxycarbonyl) glycine and tert-butyl isocyanide in Methanol-D4 by NMR spectroscopy.

Procedure

One molar methanol-D4 solutions of tert-butyl isocyanide (113uL, 1mmol) and Boc-Gly-OH(175mg, 1mmol) in CD3OD are prepared in separate 1 dram vials. 800uL of the solutions are used to obtain initial NMR spectra. Then 400uL of each solution is transfered to a clean nmr tube and shaken vigorously for a few seconds, the reaction is monitored by NMR spectra.

Results

tert-butyl isocyanide
HMR
CMR
Boc-Gly-OH
HMR
CMR
50A (Boc-Gly-OH + tert-butyl isocyanide)
t = 02min
t = 05min
t = 13min C NMR
t = 17min
t = 39min C NMR
t = 46min
t = 49min
t = 61min
t = 85min C NMR
t = 161min C NMR
t = 172 min
t = 322 min
t = 430min
t = 20h 21min C NMR (Overnight run)
t = 24h 07min

Spectral Overlays

Overlay1
Overlay2

Discussion

From the overlays it is obvious that tert-butyl isocyanide does not exhibit chemical reactivity towards Boc-Gly-OH.
All peaks in the starting materials remain unchanged over a 24 hours period .This is in sharp contrast to 2-morpholinoethyl isocyanide which looses its isonitrile identity in the presence of Boc-Gly-OH within a few minutes(Exp049).

Conclusion

Tert-butyl isocyanide like benzyl isocyanide (Exp050) may be used as an isonitrile of choice for performing Ugi reactions involving Boc-Gly-OH.

Log

2007-01-24

11:00 - Obtained a 1H NMR and a 13C NMR of tert-butyl isocyanide and Boc-Gly-OH in methanol-d4.
14:20 - Added Boc-Gly-OH solution to tert-butyl isocyanide solution.
14:22 - Obtained H NMR (t = 2min)
14:25 - Obtained H NMR (t = 5 min)
14:33 - Obtained C NMR (t = 13min)
14:37 - Obtained H NMR (t = 17min)
14:59 - Obtained C NMR (t = 39min)
15:06 - Obtained H NMR (t = 46min)
15:09 - Obtained H NMR ( t = 49min)
15:21 - Obtained H NMR (t = 61min)
15:45 - Obtained C NMR (t = 85min)
17:01 - Obtained C NMR (t = 161min)
17:12 - Obtained H NMR (t = 172min)
19:42 - Obtained H NMR (t = 322min)
21:30 - Obtained H NMR (t = 430min)

2007-01-25

10:41 - Obtained C NMR(t = 20h 21min)
14:27 - Obtained H NMR (t = 24h 07min)

Tags


t-butyl isocyanideInChI=1/C5H9N/c1-5(2,3)6-4/h1-3H3
Boc-Gly-OHInChI=1/C7H13NO4/c1-7(2,3)12-6(11)8-4-5(9)10/h4H2,1-3H3,(H,8,11)(H,9,10)