Facile synthesis of γ-alkylidenebutenolides from Morita–Baylis–Hillman adducts

Asymmetric formal synthesis of (+)-cycloclavine

The asymmetric synthesis of Szántay's amine (+)-2, the pivotal precursor for direct access to (+)-cycloclavine (1), is described for the first time in eleven steps with 19.7% overall yield from the commercially available 4-bromoindole.

Essential Oils of Morus alba and M. nigra Leaves: Effect of Drying on the Chemical Composition

Detailed GC and GC/MS analyses of essential-oil samples obtained by hydrodistillation of Morus alba L. and M. nigra L. leaves (four samples) allowed the identification of 131 constituents representing 95.1 – 96.4% of the total GC peak areas. The most abundant compounds classes were alkanes, diterpenoids, carotenoid-derived compounds and fatty acid-related constituents with trans-phytol (7.9 – 71.2%), ( E,E)-geranyl linalool (0.2 – 8.0%), ( Z)-bovolide (8.1%) and n-chain alkanes (in total, 17.5 – 52.4%) as the major constituents of the analyzed samples. In general, there were only quantitative differences noted between M. nigra essential oils from fresh and dry leaves. The most discernable changes included a variation in the content of the major constituents (e.g. the relative amount of trans-phytol and the total amount of alkanes decreased by 5.8% and ≈ 2%, respectively, while that of ( E,E)-geranyl linalool increased by 7.8%). On the other hand, the composition of M. alba essential oil was much more significantly affected by the drying process. The highest quantitative differences were noted for trans-phytol, geranyl acetone, and all isomers of 4,6,8-megastigmatrien-3-one. Also, a rare plant metabolite, ( Z)-bovolide, characteristic of leaf senescence, was only identified (8.1%) in the essential oil of M. alba dried leaves.

Natural product inspired design and synthesis of β-carboline and γ-lactone based molecular hybrids

β-Carboline and γ-lactone moieties have been selected by nature as privileged scaffolds and display a wide range of pharmacological properties. Following nature, we envisaged the preparation of new β-carboline and γ-lactone based molecular hybrids incorporating both the pharmacophores. In this regard, a water-assisted In-mediated environmentally benign and easy to execute single-step tandem Barbier type allylation-lactonisation process has been devised in order to afford the targeted molecular architectures. It is anticipated that aqueous medium plays the key role in allylation as well as in the subsequent lactonisation process for the diastereo-selective synthesis of these conjugates. It is believed that water drives the reaction pathway through dual activation, it increases the electrophilic character of formyl and ester functionalities and simultaneously enhances the nucleophilic potential of the hydroxyl group to facilitate the in situ intramolecular condensation. Importantly, during this synthetic strategy no column chromatographic purification was required at any stage.

Divergent total synthesis of triptolide, triptonide, tripdiolide, 16-hydroxytriptolide, and their analogues

A divergent route was developed for the formal total synthesis of triptolide, triptonide, and tripdiolide, as well as a total synthesis of 16-hydroxytriptolide and their analogues in an enantioselective form. Common advanced intermediate 5 was concisely assembled by employing an indium(III)-catalyzed cationic polycyclization reaction and a palladium-catalyzed carbonylation-lactone formation reaction as key steps. This advanced intermediate was readily converted to the above natural products by using palladium-catalyzed cross-coupling or the Claisen rearrangement reaction as key steps. Additionally, preliminary structure-cytotoxic activity relationship studies of C13 suggested that it might be a new modification site that could still retain the cytotoxicity.

(4R)-3-Hy-droxy-7-isopropyl-4-methyl-5,6-di-hydro-benzo-furan-2(4H)-one

In the title compound, alternatively called α-hy-droxy-γ-alkyl-idenebutenolide, C12H16O3, two independent mol-ecules (A and B) crystallize in the asymmetric unit in each of which the 5,6-di-hydro-benzo ring has an envelope conformation. The torsion angle along the butadiene chain in the γ-alkyl-idenebutenolide core is -177.9 (2)° for mol-ecule A and 179.9 (2)° for mol-ecule B. In the crystal, O-H⋯O hydrogen bonds between hy-droxyl and carbonyl groups of adjacent independent mol-ecules form dimers with R (2) 2(10) loops.

Iron-catalyzed aerobic oxidation of allylic alcohols: the issue of C═C bond isomerization

An aerobic oxidation of allylic alcohols using Fe(NO3)3·9H2O/TEMPO/NaCl as catalysts under atmospheric pressure of oxygen at room temperature was developed. This eco-friendly and mild protocol provides a convenient pathway to the synthesis of stereodefined α,β-unsaturated enals or enones with the retention of the C-C double-bond configuration.

Total synthesis of rugulovasine A

A concise total synthesis of rugulovasine A is achieved by using Uhle's ketone derivative as the key intermediate, which was synthesized by intramolecular cyclization via metal-halogen exchange. Two different routes to construct a spirocyclic butyrolactone subunit involving a Ru-catalyzed cyclocarbonylation and a special Ru-catalyzed double bond rearrangement were studied.