Three novel non-nitrogenous cassane diterpenoids from Erythrophleum suaveolens (Guill. et Perr.) Brenan (Fabaceae).

During our research to contribute to the elucidation of the chemical composition of the root bark of E. suaveolens, six non-nitrogenous cassane diterpenoids (1-6) were isolated and identified. Of these secondary metabolites, three have never been previously described: Cassan-13,15-dien-3-oxo-17-oic acid (2), Cassan-15-en-[7,17]-γ-lactone (3) and 6α-hydroxy-cassamic acid (5). The other are known but, never isolated from the root barks of E. suaveolens (Fabaceae): Cassan-13,15-dien-17-oic acid (1), 6α-hydroxy-cassamic acid methyl esther (4) and cassamic acid (6). Their structures were established according to the spectroscopic data (NMR 1D and 2D, HR-ESI-MS and IR), in comparison with those of literature. The originality of this study lies in the fact that three new natural molecules were isolated and identified. In addition, all the isolated compounds (1-6) were reported for the first time from the root barks of E. suaveolens.

Spectroscopic data of new cassane diterpenoids from the root bark of Erythrophleum suaveolens.

The data are related to the research article entitled ''New cassane diterpenoids from the root bark of Erythrophleum suaveolens'' (Jacques et al., 2019). The article provides method of purification and data to determine structure of two novel cassane diterpenoid amines: 3ß-hydroxy-3-methylbutanoyloxy-6α-hydroxy-nor-cassamine (1) and 3ß-hydroxy-3-methylbutanoyloxy-erythrosuamine (2). This data in brief provides IR, NMR and Q-TOF-MS spectra, along with fragmentation pathways that allowed to the identification of both new compounds.

Total Synthesis of γ-Indomycinone and Kidamycinone by Means of Two Regioselective Diels-Alder Reactions.

An efficient access for the synthesis of pluramycinones is described. Total syntheses of racemic γ-indomycinone and kidamycinone were achieved by means of two Diels-Alder reactions. A first Diels-Alder condensation followed by a Stille cross-coupling is used for the elaboration of the desired substituted dienes which will be involved in the second pericyclic reaction with juglone to construct the tetracyclic core of pluramycinones.

1-(2-Methyl-imidazo[1,2-a]pyridin-3-yl)-3,3-bis-(methyl-sulfan-yl)prop-2-enone monohydrate.

The title compound, C(13)H(14)N(2)OS(2)·H(2)O, appears in the form of bimolecular aggregate in which mol-ecular components are linked by O-H⋯N hydrogen bonding. The nine-membered imidazo[1,2-a]pyridine system is almost planar, with a mean deviation of 0.026 (1) Å. An intra-molecular C-H⋯O hydrogen bond forms within the imidazo[1,2-a]pyridine system. The crystal packing is consolidated by O-H⋯O and C-H⋯O hydrogen bonds, forming a supra-molecular structure consisting of perpendicular infinite mol-ecular chains running along the a and c axes.

Concise and efficient synthesis of calothrixin B.

A convergent synthesis of the naturally occurring alkaloid Calothrixin B is presented, which used a regioselective hetero-Diels-Alder reaction between a "push-pull" 2-aza-diene and a N-protected 3-bromo-9H-carbazole-1,4-dione to construct the five-ring skeleton of the molecule. Protection of the indole motif with a benzyl group was unattractive for delivery of sufficient target material because the removal of the protecting group had not been high yielding. We therefore elected to temporarily protect the indole motif with a more labile benzyloxycarbonyl group. Accordingly, the synthesis of calothrixin B proceeded in 17% overall yield over 9 steps from the commercially available 1,2,3,9-tetrahydro-4H-carbazol-4-one.