Interrupted Carbonyl‐Alkyne Metathesis

Carbonyl‐olefin metathesis and carbonyl‐alkyne metathesis represent established reactivity modes between carbonyls, alkenes, and alkynes under Lewis and Brønsted acid catalysis. Recently, an interrupted carbonyl‐olefin metathesis reaction has been reported that results in tetrahydrofluorenes via a distinct fragmentation of the reactive intermediate. We herein report the development of an analogous transformation interrupting the carbonyl‐alkyne metathesis reaction path resulting in dihydrofluorene products relying on Lewis acidic superelectrophiles as active catalytic species.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153682/1/adsc201901358.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153682/2/adsc201901358_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153682/3/adsc201901358-sup-0001-misc_information.pd

Charting a course for chemistry

To mark the occasion of Nature Chemistry turning 10 years old, we asked scientists working in different areas of chemistry to tell us what they thought the most exciting, interesting or challenging aspects related to the development of their main field of research will be — here is what they said

Functionalized Azetidines Via Visible Light-Enabled Aza Paternò-Büchi Reactions

Azetidines are four-membered nitrogen-containing heterocycles that hold great promise in current medicinal chemistry due to their desirable pharmacokinetic effects. However, a lack of efficient synthetic methods to access functionalized azetidines has hampered their incorporation into pharmaceutical lead structures. As [2+2] cycloaddition reaction between imines and alkenes, the aza Paternò-Büchi reaction arguably represents the most direct approach to functionalized azetidines. Currently, competing reaction paths accessible upon photochemical excitation of the substrates greatly restrict the synthetic utility of these transformations. We herein report the development of a visible light-enabled aza Paternò-Büchi reaction that surmounts existing limitations and represents a general solution for the direct formation of functionalized azetidines from imine and alkene containing precursors.</p

Iron-Catalyzed Synthesis of Tetrahydronaphthalenes via 3,4-Dihydro‑2<i>H</i>‑pyran Intermediates

The development of an iron­(III)-catalyzed synthetic strategy toward functionalized tetrahydronaphthalenes is described. This approach is characterized by its operational simplicity and is distinct from currently available procedures that rely on [4 + 2]-cycloadditions. Our strategy takes advantage of the divergent reactivity observed for simple aryl ketone precursors to gain exclusive access to tetrahydronaphthalene products (23 examples). Detailed mechanistic investigations identified pyrans as reactive intermediates that afford the desired tetrahydronaphthalenes in high yields upon iron­(III)-catalyzed Friedel–Crafts alkylation

8-Step Enantiodivergent Synthesis of (+)- and (-)-Lingzhiol

An 8-step enantioselective synthesis of lingzhiol is described herein. The sense of an asymmetric Michael reaction is reversed by the choice of metal source, enabling facile access to both enantiomers. A spontaneous semipinacol ring contraction enables mild construction of the lingzhiol core, and radical-mediated benzylic oxidation proceeds in the presence of an unprotected secondary alcohol. This represents the shortest enantioselective synthesis of lingzhiol to date, and the only enantiodivergent approach to both enantiomers of this meroterpenoid natural product. </div

Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl–Olefin Metathesis

Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron­(III)-catalyzed carbonyl–olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl₃ as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl–olefin ring-closing metathesis has been obtained

Aluminum Chloride-Mediated Dieckmann Cyclization for the Synthesis of Cyclic 2‑Alkyl-1,3-alkanediones: One-Step Synthesis of the Chiloglottones

Cyclic 2-alkyl-1,3-alkanediones are ubiquitous structural motifs in many natural products of biological importance. Reported herein is an AlCl₃·MeNO₂-mediated Dieckmann cyclization reaction of general synthetic utility that enables direct access to complex 2-alkyl-1,3-dione building blocks from readily available dicarboxylic acid and acid chloride substrates. This new strategy enables direct synthetic access to the chiloglottone plant pheromones from commercial material in a single synthetic transformation

Aluminum Chloride-Mediated Dieckmann Cyclization for the Synthesis of Cyclic 2‑Alkyl-1,3-alkanediones: One-Step Synthesis of the Chiloglottones

Cyclic 2-alkyl-1,3-alkanediones are ubiquitous structural motifs in many natural products of biological importance. Reported herein is an AlCl₃·MeNO₂-mediated Dieckmann cyclization reaction of general synthetic utility that enables direct access to complex 2-alkyl-1,3-dione building blocks from readily available dicarboxylic acid and acid chloride substrates. This new strategy enables direct synthetic access to the chiloglottone plant pheromones from commercial material in a single synthetic transformation