Delivery of a BET protein degrader via a CEACAM6-targeted antibody-drug conjugate inhibits tumour growth in pancreatic cancer models.

Pancreatic ductal adenocarcinoma (PDAC) has the worst prognosis of all cancers. To improve PDAC therapy, we establish screening systems based on organoid and co-culture technologies and find a payload of antibody-drug conjugate (ADC), a bromodomain and extra-terminal (BET) protein degrader named EBET. We select CEACAM6/CD66c as an ADC target and developed an antibody, #84.7, with minimal reactivity to CEACAM6-expressing normal cells. EBET-conjugated #84.7 (84-EBET) has lethal effects on various PDAC organoids and bystander efficacy on CEACAM6-negative PDAC cells and cancer-associated fibroblasts. In mouse studies, a single injection of 84-EBET induces marked tumor regression in various PDAC-patient-derived xenografts, with a decrease in the inflammatory phenotype of stromal cells and without significant body weight loss. Combination with standard chemotherapy or PD-1 antibody induces more profound and sustained regression without toxicity enhancement. Our preclinical evidence demonstrates potential efficacy by delivering BET protein degrader to PDAC and its microenvironment via CEACAM6-targeted ADC.

Fe-Catalyzed C-C Bond Construction from Olefins via Radicals.

This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C-C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl and aryl groups, additional efforts culminated in the expansion of the scope of the substitution to various heteroatom-based functionalities, providing a unified olefin reactivity. A vinyl sulfone acceptor olefin was developed, which allowed for the efficient synthesis of sulfone adducts that could be used as branch points for further diversification. Moreover, this reactivity was extended into an olefin-based Minisci reaction to functionalize heterocyclic scaffolds. Finally, mechanistic studies resulted in a more thorough understanding of the reaction, giving rise to the development of a more efficient second-generation set of olefin cross-coupling conditions.

Stainless-Steel Ball-Milling Method for Hydro-/Deutero-genation using H2O/D2O as a Hydrogen/Deuterium Source.

A one-pot continuous-flow method for hydrogen (deuterium) generation and subsequent hydrogenation (deuterogenation) was developed using a stainless-steel (SUS304)-mediated ball-milling approach. SUS304, especially zero-valent Cr and Ni as constituents of the SUS304, and mechanochemical processing played crucial roles in the development of the reactions.

Gold-Catalyzed Benzylic Azidation of Phthalans and Isochromans and Subsequent FeCl3-Catalyzed Nucleophilic Substitutions.

The benzylic positions of the phthalan and isochroman derivatives (1) as benzene-fused cyclic ethers effectively underwent gold-catalyzed direct azidation using trimethylsilylazide (TMSN3) to give the corresponding 1-azidated products (2) possessing the N,O-acetal partial structure. The azido group of the N,O-acetal behaved as a leaving group in the presence of catalytic iron(III) chloride, and 1-aryl or allyl phthalan and isochroman derivatives were obtained by nucleophilic arylation or allylation, respectively. Meanwhile, a double nucleophilic substitution toward the 1-azidated products (2) occurred at the 1-position using indole derivatives as a nucleophile accompanied by elimination of the azido group and subsequent ring opening of the cyclic ether nucleus produced the bisindolylarylmethane derivatives.

Functionalized olefin cross-coupling to construct carbon-carbon bonds.

Carbon-carbon (C-C) bonds form the backbone of many important molecules, including polymers, dyes and pharmaceutical agents. The development of new methods to create these essential connections in a rapid and practical fashion has been the focus of numerous organic chemists. This endeavour relies heavily on the ability to form C-C bonds in the presence of sensitive functional groups and congested structural environments. Here we report a chemical transformation that allows the facile construction of highly substituted and uniquely functionalized C-C bonds. Using a simple iron catalyst, an inexpensive silane and a benign solvent under ambient atmosphere, heteroatom-substituted olefins are easily reacted with electron-deficient olefins to create molecular architectures that were previously difficult or impossible to access. More than 60 examples are presented with a wide array of substrates, demonstrating the chemoselectivity and mildness of this simple reaction.

Palau'chlor: a practical and reactive chlorinating reagent.

Unlike its other halogen atom siblings, the utility of chlorinated arenes and (hetero)arenes are twofold: they are useful in tuning electronic structure as well as acting as points for diversification via cross-coupling. Herein we report the invention of a new guanidine-based chlorinating reagent, CBMG or "Palau'chlor", inspired by a key chlorospirocyclization en route to pyrrole imidazole alkaloids. This direct, mild, operationally simple, and safe chlorinating method is compatible with a range of nitrogen-containing heterocycles as well as select classes of arenes, conjugated π-systems, sulfonamides, and silyl enol ethers. Comparisons with other known chlorinating reagents revealed CBMG to be the premier reagent.

C-H methylation of heteroarenes inspired by radical SAM methyl transferase.

A practical C-H functionalization method for the methylation of heteroarenes is presented. Inspiration from Nature's methylating agent, S-adenosylmethionine (SAM), allowed for the design and development of zinc bis(phenylsulfonylmethanesulfinate), or PSMS. The action of PSMS on a heteroarene generates a (phenylsulfonyl)methylated intermediate that can be easily separated from unreacted starting material. This intermediate can then be desulfonylated to the methylated product or elaborated to a deuteriomethylated product, and can divergently access medicinally important motifs. This mild, operationally simple protocol that can be conducted in open air at room temperature is compatible with sensitive functional groups for the late-stage functionalization of pharmacologically relevant substrates.

A practical and catalytic reductive olefin coupling.

A redox-economic method for the direct coupling of olefins that uses an inexpensive iron catalyst and a silane reducing agent is reported. Thus, unactivated olefins can be joined directly to electron-deficient olefins in both intra- and intermolecular settings to generate hindered bicyclic systems, vicinal quaternary centers, and even cyclopropanes in good yield. The reaction is not sensitive to oxygen or moisture and has been performed on gram-scale. Most importantly, it allows access to many compounds that would be difficult or perhaps impossible to access using other methods.

Karlotoxin synthetic studies: concise synthesis of a C(42-63) B-ring tetrahydropyran fragment.

Starting from natural D-mannose, a C(42-63) B-ring tetrahydropyran fragment in karlotoxin 2 has been prepared via a common THP intermediate in a concise manner. E-selective Julia-Kocienski olefination efficiently assembled a C(51-63) chlorodiene subunit and a C(42-50) tetrahydropyran segment.

Chemoselective hydrogenation reaction of unsaturated bonds in the presence of an o-nitrobenzenesulfonyl group.

Chemoselective hydrogenation of unsaturated compounds bearing an o-nitrobenzenesulfonyl (Ns)-amide moiety, affording the corresponding saturated compounds, was accomplished efficiently without loss of the nitro group by using the Pd/MS3A catalyst and a H2 balloon. Partial hydrogenation of alkynes bearing an Ns group to corresponding cis alkenes was achieved with the combination of the Pd/BN catalyst and an additive (diethylenetriamine or acetic acid).

Iron-catalyzed chemoselective azidation of benzylic silyl ethers.

Azidation: siloxy groups derived from secondary and tertiary benzyl alcohols can be transformed into azide groups at room temperature using TMSN(3) in the presence of an iron catalyst (TMS=trimethylsilyl). Secondary and tertiary benzylic silyl ethers can be transformed in the presence of primary silyl ethers, and other reactive functional groups, such as alkyl chlorides, α,ß-unsaturated esters, and aldehydes, are stable under the reaction conditions.

Stereo- and regioselective direct multi-deuterium-labeling methods for sugars.

Deuterium-labeled sugars can be utilized as powerful tools for the architectural analyses of high-sugar-containing molecules represented by the nucleic acids and glycoproteins, and chiral building blocks for the syntheses of new drug candidates (heavy drugs) due to their potential characteristics, such as simplifying the (1)H NMR spectra and the stability of C-D bonds compared with C-H bonds. We have established a direct and efficient synthetic method of deuterated sugars from non-labeled sugars by using the heterogeneous Ru/C-catalyzed H-D exchange reaction in D(2)O under a hydrogen atmosphere with perfect chemo- and stereoselectivities. The direct H-D exchange reaction can selectively proceed on carbons adjacent to the free hydroxyl groups, and the deuterium labeling of various pyranosides (such as glucose and disaccharides), as well as furanosides, represented by ribose and deoxyribose was realized. Furthermore, the desired number of deuterium atoms can be freely incorporated into selected positions by the site-selective protection of the hydroxyl groups using acetal-type protective groups because the deuterium exchange reaction never proceeds on positions adjacent to the protected hydroxyl groups.

DIBAL-mediated reductive transformation of trans-dimethyl tartrate acetonide into ε-hydroxy α,ß-unsaturated ester and its derivatives.

Stepwise, selective DIBAL reduction of the acetonide diester derived from tartaric acid followed by the Horner-Emmons reaction effectively provided desymmetrized hydroxy mono-olefination products in a one-pot operation.

Geranylgeranylacetone induces cyclooxygenase-2 expression in cultured rat gastric epithelial cells through NF-kappaB.

Geranylgeranylacetone (GGA) effectively protects the gastric mucosa against noxious agents. The precise mechanisms underlying the gastroprotective actions of GGA are not known. To elucidate the precise mechanism of GGA, the effect of GGA treatment on COX-2 expression in rat gastric epithelial (RGM1) cells was investigated. We used a prostaglandin E2 (PGE2) enzyme-linked immunoassay kit and Western blot analysis to measure PGE2 production and COX-2 induction by GGA treatment in serum-starved RGM1 cells. Gel-shift assay, Western blot analysis, and a reporter assay were performed to determine which COX-2 promoter was involved in GGA-induced COX-2 expression. GGA treatment dose dependently increased COX-2 expression and PGE2 production. The nuclear factor (NF)-kappaB sites of the COX-2 gene promoter were critical for GGA-mediated COX-2 expression. GGA induces COX-2 expression and increases PGE2 production in serum-starved RGM1 cells via activation of the NF-kappaB sites of COX-2 gene promoters.

(2E,6Z,10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol (Plaunotol) increases cyclooxygenase-2 expression via nuclear factor kappaB and cyclic AMP response element in rat gastric epithelial cells.

Plaunotol, [(2E,6Z,10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetraen-1-ol], a gastroprotective agent, increases the prostaglandin production in the gastric mucosa and accelerates ulcer healing. The precise mechanisms underlying the gastroprotective actions by plaunotol are not known. On the other hand, cyclooxygenase (COX)-2 is a key enzyme in PGE(2) production and its induction is thought to have an important role in ulcer healing. We investigated the mechanism of plaunotol-mediated COX-2 induction in rat gastric epithelial (RGM1) cells. We used a PGE(2) enzyme-linked immunoassay kit and Western blot analysis to measure PGE(2) production and COX-2 induction with plaunotol treatment in serum-starved RGM1 cells. In addition, gel-shift assay, Western blot analysis and a reporter assay were performed to observe which Cox-2 promoter was involved in plaunotol-induced Cox-2 expression. The findings indicated that plaunotol treatment dose-dependently increased COX-2 expression and PGE(2) production. The nuclear factor kappaB (NF-kappaB) and cyclic AMP response element (CRE) sites of the COX-2 gene promoter were critical to plaunotol-mediated COX-2 expression. In conclusion, plaunotol induced COX-2 expression and increased PGE(2) production in serum-starved RGM1 cells via activation of the NF-kappaB and CRE sites of Cox-2 gene promoters.

Gastro-protective agent rebamipide induces cyclooxygenease-2 (COX-2) in gastric epithelial cells.

Cyclooxyngease-2 (COX-2) is a key enzyme in prostaglandin (PG) synthesis, and COX-2 induction plays an important role in the healing of gastric ulceration. Rebamipide is a gastro-protective agent and attenuates the activity of neutrophils. A number of reports have shown that rebamipide treatment increases PG production in the gastric mucosa {in vivo}. Although its clinical significance in ulcer healing has been demonstrated, {in vitro} evidence remains to be accumulated. Non-transformed rat gastric mucosal cells (RGM1 cells) were stimulated with rebamipide. RT-PCR and Western blot analysis revealed time and dose-dependent transcriptional and translational stimulation of COX-2. PGE(2) was also produced dose-dependently. However, marked COX-2 induction by rebamipide was transient and lasted less than 24 hr. COX-1 expression was unaltered by rebamipide. Reporter assay results confirmed the stimulation of Cox-2 promoter activity by rebamipide. In conclusion, this study provides {in vitro} evidence that rebamipide transcriptionally induces COX-2 and supports the rationale for its clinical use.