Chemoselective 1,2‐Reduction and Regiodivergent Deuteration of Chromium‐Bound Arenes

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(18)

Опубликована: Фев. 23, 2023

Herein, a general strategy for chemo- and regioselective 1,2-reduction of chromium-bound arenes was developed, thus providing rapid access to 1,3-cyclohexadienes. Selective arene activation via π-complexation along with the use mild hydride Ph3 SiH can overcome inherently low reactivity π-bonds while tolerating various reduction-sensitive functional groups. Its versatility further enables regiodivergent deuteration. Using different sequences (non)deuterated acid reagents, deuterated positions as well degrees deuterium incorporation be controlled precisely, which leads large previously inaccessible chemical space 1,3-cyclohexadiene isotopologues. A reasonable mechanism proposed based on intermediate capture control experiments. The synthetic value this selective demonstrated in formal total synthesis (±)-galanthamine (±)-lycoramine.

Язык: Английский

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Modern Strategies for Carbon Isotope Exchange

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(36)

Опубликована: Апрель 19, 2023

In contrast to stable and natural abundant carbon-12, the synthesis of organic molecules with carbon (radio)isotopes must be conceived optimized in order navigate through hurdles radiochemical requirements, such as high costs starting materials, harsh conditions radioactive waste generation. addition, it initiate from small cohort available C-labeled building blocks. For long time, multi-step approaches have represented sole patterns. On other side, development chemical reactions based on reversible cleavage C-C bonds might offer new opportunities reshape retrosynthetic analysis radiosynthesis. This review aims provide a short survey recently emerged isotope exchange technologies that effective opportunity for late-stage labeling. At present, strategies relied use primary easily accessible radiolabeled C1-building blocks, dioxide, monoxide cyanides, while activation principles been thermal, photocatalytic, metal-catalyzed biocatalytic processes.

Язык: Английский

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Nondirected Pd-Catalyzed C–H Perdeuteration and meta-Selective Alkenylation of Arenes Enabled by Pyrazolopyridone Ligands

ACS Catalysis, Год журнала: 2023, Номер 13(7), С. 4042 - 4052

Опубликована: Март 16, 2023

The development of ligands and the elucidation their roles in catalytic cycle are key to achieving high efficiency selectivity nondirected transition-metal-catalyzed C–H functionalization. In particular, careful ligand design can enable functionalization previously inaccessible substrate positions, which lead regiodivergent transformations common reactants. this study, a series pyrazolopyridone (PzPyOH) that be easily prepared single step was developed for Pd-catalyzed perdeuteration meta-selective alkenylation arenes. system, 2-pyridone moiety incorporated function as an internal base, facilitating cleavage rendering activation reversible, even at challenging sp2 bonds, thus enabling perdeuteration. addition, reversible bonds implies site is determined during migratory insertion reaction, thereby preferentially functionalizing meta-positions rather than typically more reactive ortho- para-positions anisole derivatives. Further, electronic structural properties pyrazole provide flexibility binding Pd, facile coordination alkene coupling partner alkenylation. process, hydrogen bonding between pyridone acetate crucial stabilize intermediates, allowing different types modes, including L,L- L,X-type bidentate monodentate binding. Kinetic computational studies support proposed mechanisms alkenylation, findings reveal factors functionalization, will useful further pyrazole- pyridone-containing transition metal catalysis.

Язык: Английский

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Recent advances in the photocatalytic synthesis of aldehydes

Organic Chemistry Frontiers, Год журнала: 2023, Номер 10(16), С. 4198 - 4210

Опубликована: Янв. 1, 2023

This review summarizes the recently developed photocatalytic strategies for installation of formyl group into various scaffolds.

Язык: Английский

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Skeletal Transformation of Unactivated Arenes Enabled by a Low-Temperature Dearomative (3 + 2) Cycloaddition

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(22), С. 12214 - 12223

Опубликована: Май 24, 2023

Simple aromatic compounds like benzene are abundant feedstocks, for which the preparation of derivatives chiefly begins with electrophilic substitution reactions or, less frequently, reductions. Their high stability makes them particularly reluctant to participate in cycloadditions under ordinary reaction conditions. Here, we demonstrate exceptional ability 1,3-diaza-2-azoniaallene cations undergo formal (3 + 2) unactivated below room temperature, providing thermally stable dearomatized adducts on a multi-gram scale. The cycloaddition, tolerates polar functional groups, activates ring toward further elaboration. On treatment dienophiles, cycloadducts (4 cycloaddition–cycloreversion cascade yield substituted or fused arenes, including naphthalene derivatives. overall sequence results transmutation arenes through an exchange carbons: two-carbon fragment from original is replaced another incoming dienophile, introducing unconventional disconnection synthesis ubiquitous building blocks. Applications this two-step acenes, isotopically labeled molecules, and medicinally relevant demonstrated.

Язык: Английский

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