Asymmetric [4+2] annulations to construct norcamphor scaffolds with 2-cyclopentenone via double amine–thiol catalysis

Antifungal Natural Products Originating from Endophytic and Rhizospheric Microbes Isolated from Coastal Vegetation

Candida infections severely impact patients who are immunocompromised. Currently, there are limited options to treat fungal infections, especially drug-resistant-fungal infections. Therefore, investigating alternative or repurposed antifungals is paramount. Endophytic microbes (EMs) and rhizospheric microbes (RMs) emerge as promising reservoirs of bioactive natural compounds. Interestingly, plants that have adapted to various environmental conditions harbour a plethora of microbes producing a variety of bioactive natural products that can be assessed for potential antifungal activity. To date, EMs and RMs residing in coastal plants and their associated antifungals have not been extensively studied or reviewed. Therefore, this comprehensive review will focus on antifungal natural products, extracted from coastal-vegetation-associated microbiota to draw the attention of research in this field. A comprehensive literature search was conducted by examining both Scopus and Google Scholar databases during the period of 2013-2024 related to the following coastal vegetation: mangroves, sand dune plants, salt marsh plants, and seagrasses. To date, 65 novel antifungal compounds derived from coastal-plant EMs and RMs have been identified. Mangroves were found to be the most prominent host harbouring antifungal-producing EMs and RMs compared with other coastal plants. Coastal-plant-associated fungal partners were the most prominent producers of antifungals compared to their bacterial counterparts. Fifty-four fungal-EM/RM derived antifungals have been reported to demonstrate activities against plant pathogenic fungi as well as human fungal pathogens. Most of the bacterial-derived antifungals (11 antifungals) have previously been reported to have antifungal activity against Candida albicans.

Tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles: construction of vicinal quaternary carbon centers

A novel tandem 1,6-addition/cyclopropanation/rearrangement reaction of vinylogous para-quinone methides with 3-chlorooxindoles has been developed, providing dispirooxindole–cyclopentane–cyclohexadienones with vicinal quaternary carbon centers.

Exploring the Role of Aminocatalysis in the Dearomatization and Regioselectivity of Heteroaromatic Aldehydes

Heteroaromatic aldehydes have recently received a lot of attention as a scaffold for aminocatalytic functionalization as they allow for the construction of remote stereocenters and highly complex heterocyclic compounds. In this paper, we employ computational methods (M06-2X/cc-pVTZ//M06-2X/6-31 + G(d,p) and MP2/cc-pVTZ//M06-2X/6-31 + G(d,p)) to examine the abilities of secondary amines to activate several model heteroaromatic aldehydes by promoting loss of aromaticity and formation of the reactive trienamine intermediate. The hyperhomodesmotic equations used to assess the energy penalty for dearomatization show that the formation of the iminium ion decreases the energy cost for dearomatization, especially when X = O and S. Furthermore, we also investigated the role that the catalyst and heteroatom may have on the orbital coefficients of the various positions of the trienamine intermediary in order to better understand and/or predict the regioselectivity these systems may showcase. Synergistic effects between the catalyst and the heteroatom of the aromatic ring were observed to increase electron density at the most remote positions of several of the model systems studied.

Asymmetric Intramolecular Rauhut-Currier Reaction and Its Desymmetric Version via Double Thiol/Phase-Transfer Catalysis

An asymmetric intramolecular Rauhut-Currier reaction of linear bis(enones) has been achieved via double activation catalysis of thiols and phase transfer substances, furnishing both enantioenriched cyclohexene and cyclopentene derivatives (up to 95% ee). Furthermore, the desymmetric version of prochiral substrates was developed under similar catalysis, producing the frameworks bearing an additional tertiary or even quaternary stereogenic center with moderate to excellent diastereo- and enantioselectivity (up to 95% ee, >19:1 dr).

Asymmetric synthesis of highly functionalized furanones via direct Michael reactions mediated by a bulky primary amine

A bulky chiral primary amine catalyzed Michael reaction of 3(2H)-furanones has been realized, leading to the construction of substituted furanone derivatives.

A 1:2 co-crystal of 2,2'-thiodi-benzoic acid and tri-phenyl-phosphane oxide: crystal structure, Hirshfeld surface analysis and computational study

The asymmetric unit of the title co-crystal, 2,2'-thiodi-benzoic acid-tri-phenyl-phosphane oxide (1/2), C14H10O4S·2C18H15OP, comprises two mol-ecules of 2,2'-thiodi-benzoic acid [TDBA; systematic name: 2-[(2-carb-oxy-phen-yl)sulfan-yl]benzoic acid] and four mol-ecules of tri-phenyl-phosphane oxide [TPPO; systematic name: (di-phenyl-phosphor-yl)benzene]. The two TDBA mol-ecules are twisted about their di-sulfide bonds and exhibit dihedral angles of 74.40 (5) and 72.58 (5)° between the planes through the two SC6H4 residues. The carb-oxy-lic acid groups are tilted out of the planes of the rings to which they are attached forming a range of CO2/C6 dihedral angles of 19.87 (6)-60.43 (8)°. Minor conformational changes are exhibited in the TPPO mol-ecules with the range of dihedral angles between phenyl rings being -2.1 (1) to -62.8 (1)°. In the mol-ecular packing, each TDBA acid mol-ecule bridges two TPPO mol-ecules via hy-droxy-O-H⋯O(oxide) hydrogen bonds to form two three-mol-ecule aggregates. These are connected into a three-dimensional architecture by TPPO-C-H⋯O(oxide, carbon-yl) and TDBA-C-H⋯(oxide, carbon-yl) inter-actions. The importance of H⋯H, O⋯H/H⋯O and C⋯H/H⋯C contacts to the calculated Hirshfeld surfaces has been demonstrated. In terms of individual mol-ecules, O⋯H/H⋯O contacts are more important for the TDBA (ca 28%) than for the TPPO mol-ecules (ca 13%), as expected from the chemical composition of these species. Computational chemistry indicates the four independent hy-droxy-O-H⋯O(oxide) hydrogen bonds in the crystal impart about the same energy (ca 52 kJ mol-1), with DTBA-phenyl-C-H⋯O(oxide) inter-actions being next most stabilizing (ca 40 kJ mol-1).