How Can Academia Help Industry Reduce the Footprint of Chemicals Manufacture?

Industrial representatives from the Swiss chemistry ecosystem met to formulate unmet needs in the field of sustainability and share the content of the exchange. The aim is to spark inspiration and trigger ambitious and pre-competitive projects collectively at the interface of the academic and industrial worlds, with the hope to profoundly change the current practices and provide an answer to some of the most urgent environmental challenges.

Swiss Women in Chemistry - Two Years Later ...

The SCS Swiss Women in Chemistry network was launched in September 2019. Under the umbrella of the Swiss Chemical Society, its aim is to create visibility, facilitate networking and provide a supportive community for female chemists in Switzerland across all career stages both in industry and academia. The current article provides an overview on the platform's activities over the past two years.

From Pine to Perfume.

CST (Crude Sulfate Turpentine) is an upcycled, biomass raw material derived from pinewood, obtained as a by-product of the Kraft process from the pulp and paper industry. The current article provides an overview of major renewable perfumery ingredients obtained from CST-derived alpha- and beta-pinene to-date and part of the Firmenich manufacturing portfolio, post DRT acquisition.

Microscale High-Throughput Experimentation as an Enabling Technology in Drug Discovery: Application in the Discovery of (Piperidinyl)pyridinyl-1H-benzimidazole Diacylglycerol Acyltransferase 1 Inhibitors.

Miniaturization and parallel processing play an important role in the evolution of many technologies. We demonstrate the application of miniaturized high-throughput experimentation methods to resolve synthetic chemistry challenges on the frontlines of a lead optimization effort to develop diacylglycerol acyltransferase (DGAT1) inhibitors. Reactions were performed on ∼1 mg scale using glass microvials providing a miniaturized high-throughput experimentation capability that was used to study a challenging SNAr reaction. The availability of robust synthetic chemistry conditions discovered in these miniaturized investigations enabled the development of structure-activity relationships that ultimately led to the discovery of soluble, selective, and potent inhibitors of DGAT1.

Discovery of Novel Indoline Cholesterol Ester Transfer Protein Inhibitors (CETP) through a Structure-Guided Approach.

Using the collective body of known (CETP) inhibitors as inspiration for design, a structurally novel series of tetrahydroquinoxaline CETP inhibitors were discovered. An exemplar from this series, compound 5, displayed potent in vitro CETP inhibition and was efficacious in a transgenic cynomologus-CETP mouse HDL PD (pharmacodynamic) assay. However, an undesirable metabolic profile and chemical instability hampered further development of the series. A three-dimensional structure of tetrahydroquinoxaline inhibitor 6 was proposed from (1)H NMR structural studies, and this model was then used in silico for the design of a new class of compounds based upon an indoline scaffold. This work resulted in the discovery of compound 7, which displayed potent in vitro CETP inhibition, a favorable PK-PD profile relative to tetrahydroquinoxaline 5, and dose-dependent efficacy in the transgenic cynomologus-CETP mouse HDL PD assay.

Oxidative cyclization of beta-hydroxyenones with palladium(II): a novel entry to 2,3-dihydro-4H-pyran-4-ones.

[reaction: see text] A palladium(II)-mediated oxidative cyclization was found to be effective for the preparation of structurally diverse 2,3-dihydro-4H-pyran-4-ones from the corresponding beta-hydroxyenones. Attractive features of this transformation include the ready availability of the starting enones, the regiocontrol, and the easy access of enantiopure 2,3-dihydro-4H-pyran-4-one from the corresponding enantiopure enone.

The organocatalytic three-step total synthesis of (+)-frondosin B.

The frondosins are a family of marine sesquiterpenes isolated from the sponge Dysidea frondosa that exhibit biological activities ranging from anti-inflammatory properties to potential application in anticancer and HIV therapy. Herein, a concise enantioselective total synthesis of (+)-frondosin B is described which requires a total of three chemical steps. The enantioselective conjugate addition of a benzofuran-derived boronic acid to crotonaldehyde in the presence of an imidazolidinone organocatalyst builds the critical stereogenic center of frondosin B in the first operation, while the remaining two ring systems of this natural product are installed in the two subsequent steps. A combination of X-ray crystallographic data, deuterium labeling, and chemical correlation studies provides further evidence as to the correct absolute stereochemical assignment of (+)-frondosin B.

Intramolecular hetero-Michael addition of beta-hydroxyenones for the preparation of highly substituted tetrahydropyranones.

Structurally diverse beta-hydroxyenones are shown to undergo nonoxidative 6-endo-trig ring closure to form highly substituted tetrahydropyranones. Amberlyst-15, Al(ClO(4))(3) x 9 H(2)O and [Pd(MeCN)(4)](BF(4))(2) were found to be suitable catalysts for these intramolecular conjugate additions, preventing side reactions, such as dehydration or retroaldolisation. The use of [Pd(MeCN)(4)](BF(4))(2) is particularly effective, as this palladium-mediated reaction is under kinetic control and generates tri- and tetrasubstituted tetrahydropyranones with high levels of diastereocontrol. In the presence of the Lewis acid Al(ClO(4))(3) x 9 H(2)O, the reaction proceeded with a similar level of diastereocontrol; however, in contrast to [Pd(MeCN)(4)](BF(4))(2), this catalyst can promote enolisation. The palladium-mediated reaction was also found to be compatible with an enantioenriched beta-hydroxyenone substrate, giving no loss of enantiopurity upon ring closure. The most distinctive synthetic development to emerge from this new chemistry is the possibility to access tri- and tetrasubstituted 2,6-anti-tetrahydropyranones from anti-aldol precursors. These compounds are particularly difficult to access by using alternative methodologies. Two modes of activation were envisaged for the ring closure, involving metal coordination to either the C=C or C=O functional groups. Experimental results suggest that C=O coordination was the preferred mode of activation for reactions performed in the presence of Al(ClO(4))(3) x 9 H(2)O or [Pd(MeCN)(4)](BF(4))(2).

Pd(II)-catalyzed cascade Wacker-Heck reaction: chemoselective coupling of two electron-deficient reactants.

A novel palladium(II)-catalyzed oxy-carbopalladation process was developed allowing for the orchestrated union of hydroxy ynones with ethyl acrylate, two electron-deficient reactants. With beta-hydroxy ynones, this cascade Wacker-Heck process gave access to highly functionalized tri- or tetrasubstituted dihydropyranones featuring an unusual dienic system. For diastereomerically pure and for enantioenriched beta-hydroxyynones, these reactions proceed without affecting the stereochemical integrity of the existing stereocenters. In addition, tetrasubstituted furanones can be prepared when alpha-hydroxyynones and ethyl acrylate are used as starting materials. The dihydropyranones and furanones obtained upon cyclization are novel compounds, but structurally related carbohydrate derivatives featuring a similar dienic system have been used as starting materials for the construction of polyannulated products, suggesting that these cascade Pd(II)-mediated oxidative heterocyclizations are of value for various synthetic applications.

Biocatalytic approaches to hetero-Diels-Alder adducts of carbonyl compounds.

Very little information is available on hetero-Diels-Alderases for the assembly of heterocyclic products despite the synthetic value of these [4+2] cycloadditions. Hetero-Diels-Alderase antibodies raised against a bicyclic transition state analogue have been generated for the cycloaddition of ethylglyoxylate with an all-carbon diene. More recently, a conceptually novel biocatalytic approach to hetero-Diels-Alder (HDA) adducts derived from carbonyl dienophiles has been developed mirroring a stepwise aldol Michael mechanism instead of a concerted pathway. In this approach, the two key steps are an antibody-mediated kinetic resolution of beta-hydroxyenones and a subsequent ring-closure process. An attractive feature of this methodology is the possibility to convert the enantioenriched aldol intermediates into tetrahydropyranones or dihydropyranones. This bioorganic route is best applied for the preparation of enantioenriched HDA adducts derived from poorly electrophilic acceptors, therefore complementing existing catalytic routes to these adducts based on the use of small organocatalysts or chiral Lewis acids.

Palladium-catalyzed oxidative cyclizations: synthesis of dihydropyranones and furanones.

A boron-mediated syn- and anti-stereoselective aldol reaction giving rise to various beta-hydroxyenones was coupled to a Pd((II))-mediated oxidative cyclization to give 2,3,6-trisubstituted syn- and anti-dihydropyranones in good yields. The Pd((II))-mediated oxidative cyclization was expanded to alpha-hydroxyenones leading to furan-3(2H)-one derivatives, which include natural product bullatenone and a known precursor of geiparvarin. The sole product of the oxidative cyclization of alpha,beta-dihydroxyenone was a five-membered furan-3(2H)-one derivative, suggesting that the ring closure of these diols is both chemo- and regioselective.

A catalytic asymmetric bioorganic route to enantioenriched tetrahydro- and dihydropyranones.

A conceptually novel approach to hetero Diels-Alder adducts of carbonyl compounds is described using as the key steps an antibody-mediated kinetic resolution of hydroxyenones followed by a ring-closure process. Various beta-hydroxyenones proved to be very good substrates for antibodies 84G3- and 93F3-catalyzed retro-aldol reactions, allowing the preparation of highly enantiomerically enriched (up to 99% ee) precursors of pyranones. An attractive feature of this methodology is the possibility to convert these acyclic-enantioenriched beta-hydroxyenones into tetrahydropyranones by a conventional Michael-type addition procedure or into the corresponding dihydropyranones using an alternative palladium-catalyzed oxidative ring closure. For the palladium-mediated cyclization, a biphasic system has been implemented that allows the direct preparation of enantiopure dihydropyranones from the corresponding racemic aldol precursors using a sequential antibody-resolution/palladium-cyclization strategy, without isolation of the intermediate enantioenriched hydroxyenones. This bioorganic route is best applied to the preparation of hetero Diels-Alder adducts otherwise derived from less nucleophilic dienes and unactivated dienophiles.