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The synthesis of campholenic-based fragrances requires the preservation of specific structural elements to capture the desired sandalwood scent. The most critical step of their preparation is the reduction of α,β-unsaturated carbonyl precursors while preserving the campholenic unsaturation. Classical reductions, especially hydrogenations, often lack complete chemoselectivity, leading to the formation of over-reduced byproducts. In addition, the stereochemistry plays a key role in the olfactory perception of these chiral fragrances. However, none of the current industrial syntheses are stereoselective, resulting in wasteful production of non-contributory isomers. Herein, we explore the untapped potential of biocatalytic reductions using ene-reductases (ERs) and alcohol dehydrogenases (ADHs) to enhance the sustainability of four commercial sandalwood fragrances (Brahmanol®, Firsantol®, Sandalore®, and Ebanol®), focusing on the stereoselective synthesis of their most odorant isomers. A comparison of green metrics, including E-factors and EcoScale, between bio- and chemo-based reductions is presented. [ABSTRACT FROM AUTHOR]

The production of essential oils by steam distillation is invariably associated with large amounts of organic waste which is normally disposed of or returned to the fields, although it may still contain some valuable components. In particular, Cannabis sativa essential oil produced by steam distillation of the apical part of industrial hemp plants yields a soaked biomass residue that may contain high-value cannabinoids. From the perspective of sustainable exploitation of agricultural resources, a method to extract cannabidiol (CBD) from such waste was demonstrated and scaled-up, using bioethanol as a renewable bio-based solvent and without requiring chromatographic separation, with an overall yield of 10.1 mg CBD per g waste. The work paves the way to an integrated complete utilisation of industrial hemp byproducts. Furthermore, two alternative lipase-mediated chemo-enzymatic derivatisations have been designed and optimised for the conversion of the recovered CBD into cannabielsoin (CBE), an underexploited cannabinoid with attractive bioactivity. The processes are practical and efficient, with 31--47% isolated yields and green metrics comparing well with the established chemical alternatives. [ABSTRACT FROM AUTHOR]

A sustainable upgrading of renewable bulk materials, obtained by decomposition of biomass lignocellulose, could facilitate their use in the industrial production of chemicals. Homogeneous ruthenium catalysis plays a fundamental role in this area. The review deals with the upgradation of lignocellulosic molecules through the formation of new C−C and C−N bonds. Selected examples of catalytic bond forming reactions reported until mid of 2023, include: (a) dehydrogenative based couplings of alcohols, (b) reductive amination of carbonyl compounds, (c) direct C−H functionalization of (hetero)aromatic compounds. These approaches fulfill the requirements of sustainability: application occurs without any previous substrate activation, thus reducing the production of waste. New chemicals containing the intrinsic molecular structure of lignocellulose substrates, showed a broad range of applications: green fuels, hydrogen carriers, monomers of polymers, intermediates of fine chemicals and pharmaceuticals. The results discussed in the review could inspire the reader to improve the valorization process, in terms of bio‐substrate scope as well as product complexity, through more strategic applications of the catalytic methods. [ABSTRACT FROM AUTHOR]

Late‐Stage Functionalisation (LSF) is an innovative technique that has been successfully applied to the C−H diversification of pharmaceuticals. However, LSF of the pyridine ring in drug‐like molecules is often unselective. As a result, a mixture of structurally related products is obtained, thus making the purification tedious and time‐consuming. This review shines a light on recent strategies addressing the selectivity issue in the LSF of complex natural products or drugs containing the pyridine moiety. Specifically, we have reviewed the efforts reported both in academia and industries with the hope of providing a guide for the LSF of elaborated pyridines. [ABSTRACT FROM AUTHOR]

At the forefront of chemistry and biology research, development timelines are fast‐paced and large quantities of pure targets are rarely available. Herein, we introduce a new framework, which is built upon an automated, online trapping‐enrichment multi‐dimensional liquid chromatography platform (TE‐Dt‐mDLC) that enables: 1) highly efficient separation of complex mixtures in a first dimension (1D‐UV); 2) automated peak trapping‐enrichment and buffer removal achieved through a sequence of H2O and D2O washes using an independent pump setup; and 3) a second dimension separation (2D‐UV‐MS) with fully deuterated mobile phases and fraction collection to minimize protic residues for immediate NMR analysis while bypassing tedious drying processes and minimizing analyte degradation. Diverse examples of target isolation and characterization from organic synthesis and natural product chemistry laboratories are illustrated, demonstrating recoveries above 90 % using as little as a few micrograms of material. [ABSTRACT FROM AUTHOR]

One-pot reactions elaborated around transition metal-catalyzed isomerization of alkenes not only offer the inherent advantages of atom-, step- and redox-economy but also enable the preparation of value-added products that would be difficult to access by conventional methods. In this Review, we cover seminal and recent examples of tandem, sequential and domino processes, which incorporate the most attractive features of olefin isomerization. [ABSTRACT FROM AUTHOR]

Keywords: Functionalisation; Late-stage; N-heterocycle; Pyridines; Selectivity EN Functionalisation Late-stage N-heterocycle Pyridines Selectivity 1 1 1 04/24/23 20230420 NES 230420 B The Front Cover Cover b illustrates how the pyridine ring of the antihistamine loratadine can be selectively functionalised at the I ortho i -, I meta i -, or I para i -position (each of them activated by a thunder). Indeed, the selective functionalisation of this N-heterocycle is often problematic, thus a lighthouse guides the chemists through the late-stage functionalisations of pyridine-containing biomolecules. Functionalisation, Late-stage, N-heterocycle, Pyridines, Selectivity. [Extracted from the article]

Palladium-catalyzed intramolecular asymmetric allylic alkylation was used for the first time to prepare 4-vinyltetrahydrocarbazole 3. Suitable indole-containing allylic carbonates were synthesized and cyclized in the presence of a chiral catalyst formed in situ from Pd(OAc)2 and members of the PhthalaPhos ligand library (i.e., 1,1′-bi-2-naphthol-monophosphites possessing a phthalic acid diamide group). The use of a stable and readily available palladium source such as Pd(OAc)2-reduced in situ by the phosphite to form the Pd0 catalyst-allowed better and more reproducible results to be obtained relative to the results achieved by using [Pd2(dba)3 ·CHCl3] (dba = dibenzylideneacetone) and [Pd(allyl)Cl]2. A ligand screening led to identification of the best ligand [( S)- L1], which, after optimization of the reaction parameters, gave product 3 with 75 % ee. Remarkably, the reaction turned out to be stereodivergent: by using ligand ( S)- L1, the absolute configuration of product 3 was found to depend on the geometry of the substrate's double bond [( E)-substrate → ( S)- 3, ( Z)-substrate → ( R)- 3]. [ABSTRACT FROM AUTHOR]

A detailed investigation is presented concerning the choice of Pd source, PhthalaPhos ligand, solvent, temperature and Pd-ligand ratio. [ABSTRACT FROM AUTHOR]

At the forefront of chemistry and biology research, development timelines are fast-paced and large quantities of pure targets are rarely available. Herein, we introduce a new framework, which is built upon an automated, online trapping-enrichment multi-dimensional liquid chromatography platform (TE-Dt-mDLC) that enables: 1) highly efficient separation of complex mixtures in a first dimension ( 1 D-UV); 2) automated peak trapping-enrichment and buffer removal achieved through a sequence of H 2 O and D 2 O washes using an independent pump setup; and 3) a second dimension separation ( 2 D-UV-MS) with fully deuterated mobile phases and fraction collection to minimize protic residues for immediate NMR analysis while bypassing tedious drying processes and minimizing analyte degradation. Diverse examples of target isolation and characterization from organic synthesis and natural product chemistry laboratories are illustrated, demonstrating recoveries above 90 % using as little as a few micrograms of material., (© 2022 Wiley-VCH GmbH.)

A [Ni/Mg]-catalyzed orthogonal tandem polymerization has been developed starting from enol phosphates. Initial investigations conducted on branched 1,3-dienes as monomers enabled identification of a Mg-initiated polymerization process leading to 1,4- cis -polydienes. When aryl enol phosphates are used as monomers, the [Ni/Mg]-catalyzed tandem polymerization affords 1,4- cis -polydienes with selectivities up to 99%. Elastomeric or crystalline materials were obtained by simple structural modifications of the monomeric unit. This tandem approach appears as a straightforward and efficient way to enforce diversity and selectivity in diene polymerization while retaining a fair degree of control, just as observed for stepwise systems that are accessible through established time- and manpower-consuming synthetic procedures.

A Cu-catalyzed borylative carboxamidation reaction has been developed using vinylarenes and isocyanates. Alkynes, branched 1,3-dienes, and bicyclic alkenes were also found to be competent coupling partners. Using a chiral phosphanamine ligand, an enantioselective variant of this transformation was developed, affording a set of α-chiral amides with unprecedented levels of enantioselectivity. The synthetic utility of the method was demonstrated through a series of representative stereoretentive postcatalytic derivatizations.