4-ethylbenzaldehyde

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:90.01; pressure:0.00; stir:

Conditions: temp:90.01; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The same method but starting from racemic tryptophan methyl ester and 4-ethylbenzaldehyde gave the cis and trans isomer of the title compound. Cis isomer: white solid 1H NMR (CDCl3) δ(ppm): 7.65-7.1 (m, 9H, H aromatic); 5.25 (brs, 1H, H-1); 4(dd, 1H, H-3); 3.9 (s, 3H, CO2CH3); 3.4 (ddd, 1H, H-4); 3.1 (m, 1H, H-4); 2.7 (q, 2H, CH2CH3) 1.4 (t, 3H, CH2CH3). Trans isomer: white solid m.p.: 187° C.