Total Synthesis of (±)‐1‐Acetylaspidoalbidine and (±)‐1‐Methylaspidospermidine

Abstract

(AE)-1-Acetylaspidoalbidine and (AE)-1-methylaspidospermidine were synthesized from protected tryptamine through the combination of an organocatalytic Diels-Alder reaction, a tandem stereoselective ring-opening reduction, and a double Michael addition.

Activation of a Cryptic Gene Cluster in Lysobacter enzymogenes Reveals a Module/Domain Portable Mechanism of Nonribosomal Peptide Synthetases in the Biosynthesis of Pyrrolopyrazines

“…Comparison of the NMR data of 2 and 1 (Table S5) indicated that 2 had the same pyrrolo[1,2-α]pyrazine-4-one moiety, but the side chain of 2 was replaced by an isobutyl group. On the basis of assignments of the proton-bearing carbon and corresponding proton resonances (Table S5) in the NMR spectra by gHSQC, gCOSY cross-peaks, and HMBC correlations (Figures S13, S23–S27), the structure of 2 was established to be 1-benzoyloxy-3-isobutyl-7,8-dihydro-6 H -pyrrolo[1,2-α] pyrazine-4-one, which is consistent with the literature, 13 and 2 was named Le-pyrrolopyrazine B.…”

N‐Alkoxyacrylamides in Domino Reactions: Catalytic and Stereoselective Access to δ‐Lactams

“…In that context, we hypothesized that an expedient entry to δ‐lactam (δ‐valerolactam or piperidin‐2‐one) compounds might be conceivable by a novel aza‐MIRC process using bifunctional secondary acrylamide derivatives, which bear both a nucleophilic nitrogen atom and an electrophilic double bond (Scheme ) . Curiously, in spite of their inherent ambivalent reactivity, and promising synthetic potential thereof, acrylamides have been largely neglected as formal dipolar building blocks for the synthesis of nitrogen heterocycles . Thus, to the best of our knowledge, no direct aza‐MIRC sequence using acrylamides to synthesize δ‐lactams has been described to date .…”

Total Synthesis of Aspidosperma and Strychnos Alkaloids through Indole Dearomatization

“…As ar esult, severalc atalytic asymmetric conjugate additions of C2-substitutedt ryptamines to propargylic aldehydes and ketones have been developed. [57] As an alternative to the biomimetic Diels-Alder approach, Kraus et al have developed an intramolecular [4+ +2]-cycloaddition (Scheme 25). [58] Diels-Alder substrate 223 was obtained efficientlyf rom 3-acetylindole, by first tethering the dienophile followed by conversion of ketone 222 to silyl enol ether 223.…”