Total synthesis of maremycins A, B, C1/C2, D1, and D2

The total synthesis of maremycins A, B, C1/C2, D1, and D2 is achieved starting from the natural amino acids l-isoleucine and S-methyl-l-cysteine, in which the total synthesis of maremycins B, C1/C2, and D2 is accomplished for the first time. The synthesis features a position-selective intramolecular bromination process for the synthesis of key chiral building block, a Pd-catalyzed indole synthesis for the preparation of (2S,3S)-β-methyltryptophan and hydroxylation of oxindoles by molecular oxygen. In addition, the protocol for conversion of maremycins A and B to maremycins C and D was improved.