06.06.2013 Views

Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

Solution and Solid Phase Synthesis of Unusual a-Amino Acids From

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Cbz-L-Glu(Z-B,y-dehydro)(OMe)OBO 499 (0.150 g, 0.40 rnmol) <strong>and</strong> N-methylrnorph-<br />

oline (0.049 g, 0.42 rnmol) were combined <strong>and</strong> dissolved in acetone:water (4: 1,s mL) to<br />

which Os04 (1 grain) was added. After the mixture had stined for 48 hours at room<br />

temperature the solvent was reduced in vacuo, dissolved in methanol (20 mL), reduced<br />

again then dissolved in a minimum <strong>of</strong> methanol to which an equal amount <strong>of</strong> Et0Ac:Hex<br />

(2: 1) was added <strong>and</strong> then flash chromatographed to give 0.074 g (45% yield) <strong>of</strong> 4.101 as<br />

a light coloured oïl.<br />

[al2'o = +4.4 (c = 0.9, CH5Cl2); TLC (2: 1, EtOAc:Hex), Rr = 0.21; 'H NMR (Acetone-Q,<br />

300 MHz) 6 7.40-7.26 (m, 5H, ArH), 6.09 (d, IH, J = 10.3Hz. NH), 5.07 (s, 2H,<br />

CbzCH20), 4.66 (br d, lH, J = 7.3Hz, yrCH), 4.16 (dd, IH, J = 9.8, 10.3Hz, a-CH), 3.91<br />

(s, 6H, OB0 ester CHB), 3.83 (dd, lH, J = 7.3, 9.8Hz, p-CH) 3.66 (s, 3H, C02CH3),<br />

0.80 (s, 3H, OB0 ester CC&); I3c NMR (Acetone-4, 75 MHz) 6 172.8 C=O), 156.7<br />

(CONH), 137.4 (Cbz*), 128.4, 127.8, 127.8 (Cbz=CJI=), 108.6 (OB0 ester -O),<br />

72.4 (OB0 ester cH20), 71.5 (PSH), 70.8 (y=, 66.1 (CbzÇ&O), 53.8 (a-CH), 50.9<br />

(COS&), 30.4 (OB0 ester CCH3), 13.2 (OB0 ester CcH3); IR (cast from CHzClz)<br />

3447,2953,2883, 1734, 1717, 1521, 1228, 1048; ESI-MS (M + 412.15; Anal. cdcd<br />

for ClgHsNQ: C, 55.47; H, 6.12; N, 3.04. Found: C, 55.69; H, 6.24; N, 3.06.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!