A total synthesis of (−)-antimycin A3b

Antimycin-type depsipeptides: discovery, biosynthesis, chemical synthesis, and bioactivities

“…3) and a diastereomeric mixture of 6 ( Fig. [65][66][67][68][69] These early attempts had low efficiency in the construction of the 9-membered dilactone ring (0.8-20% ring-closure yield) and the stereochemistry at the C7 and C8 positions. 62,63 The synthesis of naturally occurring (+)-6 was then investigated by the same research group a few years later, 64 and this report was followed by the syntheses of 6 and 7 by several other groups.…”

A New Fungicide Produced by a Streptomyces sp. GAAS7310

“…Subsequently Abide et al isolated the mixture of antimycins A into eight hitherto subcomponents, A1a, A1b, A2a, A2b, A3a, A3b, A4a and A4b by HPLC [7] and identified the structure of A1a by 1D, 2D NMR and X-ray [8,9]. Tsunoda et al had accomplished the total synthesis of antimycin A 3b [10]. Compared with known antimycin A series, compound 1 is different at the 7-position.…”

Natural occurrence, biological activities and synthesis of eight-, nine-, and eleven-membered ring lactones

“…68 The synthesis of unnatural (-)-antimycin A 3b (ent-96) reported by Tsunoda et al 69 started from (R)-(+)-methylbenzylamine, which was transformed in the amide 101 in three steps. The aza-Claisen rearrangement of 101 led the expected amide as a mixture of four stereoisomers, from which the main isomers 102a and 102b could be obtained as a unseparable 4:1 mixture, respectively.…”

“…The authors used (S)-(-)-methylbenzylamine for the preparation of the seco acids 108c/108d, following the same sequence of reactions early used for the synthesis of unnatural ent-96. 69 Corey-Nicolaou lactonization 14 of 108c/108d, using Cu(OTf) 2 .PhH complex instead the explosive AgClO 4 metal salt, afforded a separable mixture of the nine-memebered dilactones 109c/109d in 88% yield. Removal of the TIPS-protecting group, followed by esterification of the free hydroxyl group of 109c with (S)-and (R)-2-methylbutanoic acid allowed the establishment of the S-configuration at the C2´ position in the natural (+)-95 (Scheme 18).…”