No abstract

No abstract

Macrocyclic bisindolylmaleimides 1−4 have been identified as competitive reversible inhibitors of PKC β1 and β2 and are being advanced to the clinic for evaluation as a treatment of retinopathy associated with diabetic complications. Highly convergent and stereoselective syntheses of 1−4 have been developed. The key synthetic step involves intermolecular alkylation of symmetrical bisindolylmaleimide 9 with chiral bisalkylating agent 8c and is amenable to the preparation of multikilogram quantities of these compounds. The synthetic sequence to 1, the most active compound, proceeds in 11 steps and 26% overall yield (>98% ee) from (R)-1-chloro-2,3-propanediol. No chromatographic purifications are required throughout the process and the final product is isolated in >97% purity after crystallization from DMF/MeOH. Synthesis of 1−4 by intramolecular alkylation proved less efficient, requiring 17 steps and affording 1−4 in lower overall yields of 6.0−8.5%.

Glycosylated 7-chloroindole-3-acetamide 9, prepared in four steps and 26% yield from 7-chloroindole (1), was condensed with methyl 7-chloroindole-3-glyoxylate 11 and methyl indole-3-glyoxylate 12 to provide bisindolylmaleimides 7 and 8 in 86% and 84% yield, respectively. Oxidation of 7 and 8 followed by debenzylation provided a new approach to the synthesis of rebeccamycin and completed for the first time a synthesis of 11-dechlororebeccamycin.

No abstract