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

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

238.3; Anal. calcd for Cl2H1&O4Cl: C, 52.66; H, 5.89; N, 5.12. Found: C, 52.90; H,<br />

6.02; N, 5-14.<br />

4.4.48 (2S,4S)-2-~d-hydn,xypentanedioic acià, (2S,4S)-Hydroxy6lutPmieouc acid,<br />

See General Procedure for Removal <strong>of</strong> Rotecting Groups.<br />

[a]*OD = +60.3 (c = 0.9,6N HCI ) (iit." [al2'D = +61 (c = 1,5N HCI); 'H NMR (&O, 300<br />

MHz) 6 4.03 (dd. lH, J = 4.4, 7.8 Hz. YCH), 3.73 (dd, lH, J = 3.4.7.9 Hz, a-CH), 2.14-<br />

2.00 (m, W, fbCH2); 13c NMR (D20. 75 MHz) 6 182.6 ad)), 178.7 (C=O), 69.9 (y-<br />

- CH), 51.8 (a-CH), 39.5 ($-); ESI-MS (M + H+') 163.87. Anal. calcd for CsH&iOsCI:<br />

C, 30.09; H, 5.05; N, 7.02. Found: C, 30.4 1 ; H, 5.35; N, 7.24.<br />

4.4.49 (~~R)-2-amin013-hydroxypentsnedioic acid, 4.7.<br />

Cbz-L-Glu@-OH)(OtBu)OBO ester 4.104 (0.098 g, 0.22 rnrnol) was stirred in fresh<br />

TMSI (500 pL, 3.5 mmol) at 75°C for 24 h. After cooling, Et20 (3 mL) was slowly<br />

added followed by the dropwise addition <strong>of</strong> OSN NaOH (5 mL). The organic layer was<br />

carefully removed by pipette <strong>and</strong> washed with 0.5N NaOH (2 x 3 mL). The aqueous<br />

fractions were combined, washed with Et20 (2 x 5 mL) then acidified to pH

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

Saved successfully!

Ooh no, something went wrong!