SYNTHESES OF FURTHER ANALOGUES OF NORPHALLOIN. GLY1‐, L‐VAL1‐ AND D‐ABU2‐ NORPHALLOIN AND (β‐TRIDEUTERO)‐ALA5‐ NORPHALLOIN*

The norphalloin analogues with glycine and L-valine instead of L-alanine in position 1, (II and III), with D-α-aminobutyric acid instead of D-threonine in position 2 (IV), and with β-trideutero-L-alanine instead of L-alanine in position 5 (β-D3-I), have been synthesized according to Chart I, mainly using the mixed anhydride method. For the final cyclization step to III the p-nitrophenylester method was employed. Analogue IV showed toxicity in the white mouse with doses <5 mg per kg body weight, whereas II and III were nontoxic. The deuterated norphalloin analogue proved by p.m.r. measurement that in fact the methyl group of alanyl residue no.5 is located above the indole nucleus, as suggested in a former publication (4).