Total synthesis of (S)-(+)-curcudiol, and (S)-(+)- and (R)-(-)-curcuphenol

Enantioselective Ir-Catalyzed Hydrogenation of Terminal Homoallyl Sulfones: Total Synthesis of (-)-Curcumene

A novel methodology for the preparation of chiral methyl benzylic compounds is reported. Terminal homoallyl sulfones were prepared from homoallyl alcohols, which are easily accessible through the recently reported Lewis acid isomerization of oxetanes. The iridium-catalyzed asymmetric hydrogenation of homoallylic sulfones afforded γ-chiral sulfones with excellent enantioselectivities (up to 98% ee). The synthetic potential of this novel methodology was demonstrated by the total synthesis of (R)-(-)-curcumene.

In Silico Evaluation of Antifungal Compounds from Marine Sponges against COVID-19-Associated Mucormycosis

The world is already facing the devastating effects of the SARS-CoV-2 pandemic. A disseminated mucormycosis epidemic emerged to worsen this situation, causing havoc, especially in India. This research aimed to perform a multitargeted docking study of marine-sponge-origin bioactive compounds against mucormycosis. Information on proven drug targets and marine sponge compounds was obtained via a literature search. A total of seven different targets were selected. Thirty-five compounds were chosen using the PASS online program. For homology modeling and molecular docking, FASTA sequences and 3D structures for protein targets were retrieved from NCBI and PDB databases. Autodock Vina in PyRx 0.8 was used for docking studies. Further, molecular dynamics simulations were performed using the IMODS server for top-ranked docked complexes. Moreover, the drug-like properties and toxicity analyses were performed using Lipinski parameters in Swiss-ADME, OSIRIS, ProTox-II, pkCSM, and StopTox servers. The results indicated that naamine D, latrunculin A and S, (+)-curcudiol, (+)-curcuphenol, aurantoside I, and hyrtimomine A had the highest binding affinity values of -8.8, -8.6, -9.8, -11.4, -8.0, -11.4, and -9.0 kcal/mol, respectively. In sum, all MNPs included in this study are good candidates against mucormycosis. (+)-curcudiol and (+)-curcuphenol are promising compounds due to their broad-spectrum target inhibition potential.

A look around the West Indies: The spices of life are secondary metabolites

Natural products possess a wide range of bioactivities with potential for therapeutic usage. While the distribution of these molecules can vary greatly there is some correlation that exists between the biodiversity of an environment and the uniqueness and concentration of natural products found in that region or area. The Caribbean and pan-Caribbean area is home to thousands of species of endemic fauna and flora providing huge potential for natural product discovery and by way, potential leads for drug development. This can especially be said for marine natural products as many of are rapidly diluted through diffusion once released and therefore are highly potent to achieve long reaching effects. This review seeks to highlight a small selection of marine natural products from the Caribbean region which possess antiproliferative, anti-inflammatory and antipathogenic properties while highlighting any synthetic efforts towards bioactive analogs.

Stereoselective Synthesis of Terpenoids through Lipase-Mediated Resolution Approaches

This review article focuses on the scientific developments concerning the lipase-mediated synthesis of terpenoids that have been reported in the literature during the last twenty years. More specifically, this review describes in depth the resolution approaches that allow the preparation of the chiral building blocks used for the stereoselective synthesis of bioactive terpenoids. The synthetic methods that have given new and innovative perspectives from a scientific standpoint, and the preparative approaches that possess industrial importance, are described thoroughly.

Highly Enantioselective Asymmetric Hydrogenation of Carboxy-Directed α,α-Disubstituted Terminal Olefins via the Ion Pair Noncovalent Interaction

The t-Bu-Wudaphos was successfully applied into Rh-catalyzed asymmetric hydrogenation of α,α-disubstituted terminal olefins bearing a carboxy-directed group with excellent reactivities and enantioselectivities via the ion pair noncovalent interaction (up to >99% conversion, 98% yield, 98% ee) under mild reaction conditions without base. In addition, control experiments were conducted, and the results demonstrated that the ion pair noncovalent interaction between ligand and substrate played an important role in achieving an outstanding performance in this asymmetric hydrogenation.

Carboxy-directed asymmetric hydrogenation of α-alkyl-α-aryl terminal olefins: highly enantioselective and chemoselective access to a chiral benzylmethyl center

A carboxy-directed asymmetric hydrogenation of α-alkyl-α-aryl terminal olefins was developed by using a chiral spiro iridium catalyst, providing a highly efficient approach to the compounds with a chiral benzylmethyl center. The carboxy-directed hydrogenation prohibited the isomerization of the terminal olefins, and realized the chemoselective hydrogenation of various dienes. The concise enantioselective syntheses of (S)-curcudiol and (S)-curcumene were achieved by using this catalytic asymmetric hydrogenation as a key step.

Bioactive Semisynthetic Derivatives of (S)-(+)-Curcuphenol

New semisynthetic sesquiterpene derivatives (3–7, 10), together with two known ones (8–9) were prepared from ( S)-(+)-curcuphenol (1), isolated from the Caribbean sponge Didiscus oxeata. The natural sesquiterpenes 1 and ( S)-(+)-curcudiol (2), as well as semisynthetic derivatives 3–10, were evaluated against the herbivorous insect species Spodoptera littoralis, Leptinotarsa decemlineata and Rhopalosiphum padi. All compounds had an antifeedant effect on L. decemlineata. With R. padi, a structure-dependent antifeedant response was observed, with 1 being the most active, followed by 4 and 5. Furthermore, compounds 1, 4, 5, 7, 8 and 10 reduced S. littoralis larval weight, with 10 also reducing ingestion by S. littoralis larvae. Of the derivatives studied here, none showed stronger effects (either antifeedant or postingestive) than the parent compound 1. It can, therefore, be concluded that the structure of the side chain and the presence of the phenol ring of curcuphenol are important structural requirements for its insect antifeedant and growth regulation effects.

Chemical transformation and biological studies of marine sesquiterpene (S)-(+)-curcuphenol and its analogs

Chemical transformation studies of the marine sesquiterpene phenol (S)-(+)-curcuphenol (1), isolated from the Jamaican sponges Myrmekioderma styx, were accomplished. In order to optimize the activity and better understand the SAR of (S)-(+)-curcuphenol, nineteen semisynthetic analogs were prepared and evaluated for activity against infectious diseases. A number of analogs showed significant activity against Mtb and Leishmania donovani, while showed good to moderate activities in antibacterial and antifungal assays as well as against Plasmodium falciparium (D6 clone) and (W2 clone). The analogs a, c, h, and r exhibited Mtb activity with MICs of 24.6, 41.2, 6.90, and 50.5 microM, respectively. Analog f showed enhanced activity against L. donovani with an IC50 of 0.6 microM and IC90 of 40 microM respectively.

Stereochemical determination and bioactivity assessment of (S)-(+)-curcuphenol dimers isolated from the marine sponge Didiscus aceratus and synthesized through laccase biocatalysis

Electrospray ionization mass spectrometry-guided isolation of extracts from Didiscus aceratus led to the discovery of several new derivatives of the bioactive bisabolene-type sponge metabolite (S)-(+)-curcuphenol (1). The compounds obtained by this method included a mixture of known (2) and new (3) dihydroxylated analogs as well as a novel family of dimeric derivatives, dicurcuphenols A-E (4-8), and dicurcuphenol ether F (9). Dimers 4-9 were also subsequently obtained through a hemisynthetic method in which 1 was incubated with the enzyme laccase. Atropisomeric dimers 5 and 6 were subjected to vibrational circular dichroism analysis thereby establishing their absolute biaryl axial chirality as P and M, respectively. In contrast to 1, metabolites 2-9 exhibited weak or no cytotoxic or lipoxygenase inhibitory effects.

Enzymatic Resolution of (.+-.)-5-Acetoxy-4-aryl-(2E)-pentenoate Derivatives

Enzymatic resolution of six (+/-)-5-acetoxy-4-aryl-(2E)-pentenoate derivatives, compounds 9, 11, 13, 15, 17, and 19 bearing a different aromatic substitution pattern, using lipase OF-360 from Candida rugosa was carried out. The absolute configurations of all hydrolyzed products and all unchanged acetates were found to be S and R, respectively. Moreover, the enantiomeric excess of the enzymatic resolution products from 9, 11, and 13 with the ortho-methoxyl group in the aromatic ring was higher than that of the substrates with no methoxyl group at the ortho-position in the aromatic ring.