ugicycdce.JPG

Objective

To cyclize a Ugi product to form a diketopiperazine via a boc-deprotected intermediate . This Ugi product was synthesized here.

Procedure

Prepared 10% TFA solution by adding 80uL TFA to 1 dram vial. Added 720uL1,2 dichloroethane. Took NMR spectra. Added 50mg Ugi Product (62E) to NMR tube and monitored reaction via NMR spectra at specific intervals.

Results

10% TFA Solution
HNMR

62E
HNMR

Ugi/TFA before reflux (T=50 mins)
HNMR

T=24hrs
HNMR

Discussion

1. The de-protection is evident with the appearance of a singlet peak at 1.6ppm (corresponding to t-butyl trifluoroacetate) after 50 mins.
2. After twenty four hours the Ugi product is completely de protected, although this is somewhat unreliable because the reaction evaporated.

Conclusion

The Ugi product was deprotected however the product did not cyclize.

Log

2007-03-28

11:17 Set temperature bath to 80C. Prepared 10% TFA solution.
11:46 Added 400uL TFA solution to NMR tube. Added 400uLdeuterated chloroform to NMR tube. Took NMR spectra.(solution slight yellow)
12:38 Unable to get spectra until 12:30. Weighed out 50mg of 62E. Added to contents of NMR tube. (solution orange-red)
12:46 Took NMR spectra.
13:43 Unable to get spectra until 13:35. Temperature bath at 81C. Placed NMR tube in temperature bath. Solution turned red.
13:57 Noticed condensation in NMR tube. Temperature bath 81C.
14:30 Contents in NMR tube evaporated. Removed from heat.
16:12 Added 500uL deuterated chloroform to NMR tube.

2007-03-29

13:10 Took NMR spectra.

Tags

UgiproductInChI=1/C26H35N3O7/c1-16-8-10-18(35-16)14-29(21(30)13-27-24(32)36-26(5,6)7)22(23(31)28-25(2,3)4)17-9-11-19-20(12-17)34-15-33-19/h8-12,22H,13-15H2,1-7H3,(H,27,32)(H,28,31) (why are there extra characters not in the URL?)
DKP065 InChI=1/C17H16N2O5/c1-10-2-4-12(24-10)8-19-15(20)7-18-17(21)16(19)11-3-5-13-14(6-11)23-9-22-13/h2-6,16H,7-9H2,1H3,(H,18,21)



external image exp065&js=1&rnd=0.24369077888991708