Generation of alkyl and acyl radicals by visible-light photoredox catalysis: direct activation of C–O bonds in organic transformations

• Mithu Roy,
• Bitan Sardar,
• Itu Mallick and
• Dipankar Srimani

Beilstein J. Org. Chem. 2024, 20, 1348–1375, doi:10.3762/bjoc.20.119

• [28] introduced the photoredox-catalyzed hydroacylation of styrene derivatives via deoxygenation of challenging aliphatic carboxylic acids (Scheme 1). The deoxygenation was promoted by phosphine reagents to form acyl radicals. The acyl radicals reacted with the C=C bond and formed the expected product

• hydroacylation of azobenzenes employing acids as hydroacylating reagents (Scheme 4). The reaction progressed smoothly, involving the cleavage of the C–O bond using a photogenerated phosphoranyl radical. The methodology demonstrated an excellent compatibility with a wide range of azobenzenes and carboxylic acids

• photocatalytic mechanism. Photoredox-catalyzed hydroacylation of olefins with aliphatic carboxylic acids. Acylation–aromatization of p-quinone methides using carboxylic acids. Visible-light-induced deoxygenation–defluorination for the synthesis of γ,γ-difluoroallylic ketones. Photochemical hydroacylation of

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• hydroacylation on alkynyl compound 124 to construct the cyclooctanone unit. Despite several attempts, no cyclization occurred (Scheme 24). 3 Pd-mediated cyclization 3.1 Pd-promoted intramolecular alkenylation of methyl ketone: synthesis of cotylenin A (130) Nakada exploited the usefulness of a Pd-promoted

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• iridium-catalyzed hydroacylation of C1-substituted oxabenzonorbornadienes with salicylaldehyde is reported. Utilizing commercially available [Ir(COD)Cl]2 in the presence of 5 M KOH in dioxane at 65 °C, provided a variety of hydroacylated bicyclic adducts in up to a 95% yield with complete stereo- and

• regioselectivity. The mechanism and origins of selectivity in the iridium-catalyzed hydroacylation reaction has been examined at the M06/Def2TZVP level of theory. The catalytic cycle consists of three key steps including oxidative addition into the aldehyde C–H bond, insertion of the olefin into the iridium

• hydride, and C–C bond-forming reductive elimination. Computational results indicate the origin of regioselectivity is involved in the reductive elimination step. Keywords: C–H activation; density functional theory; hydroacylation; iridium catalysis; regioselectivity; Introduction Organic synthesis is

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• corresponds to the observed major isomer product (Figure 15). In a related transformation, Hong realized the exclusively α-selective hydroacylation of ynones, ynoates, and ynamides via photoredox nickel catalysis. Thus, the combination of nickel and iridium catalysts efficiently catalyzed the regioselective α

Aldehydes as powerful initiators for photochemical transformations

• Maria A. Theodoropoulou,
• Nikolaos F. Nikitas and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76

• hydroacylation of Michael acceptors under irradiation with 80 W household bulbs [59]. 4-Cyanobenzaldehyde (53) exhibited the highest yield (86%) among 25 substituted benzaldehydes in the reaction between diethyl maleate (154) and octanal (155) (Scheme 36). During the optimization, different solvents, catalyst

• products yielded by the photochemical alkylation reaction of N-containing molecules. C(sp3)–H functionalization of thioethers. Proposed mechanism for the C(sp3)–H alkylation/arylation of N-containing molecules and thioethers. Hydroacylation using 4-cyanobenzaldehyde (53) as the photoinitiator. Selectivity

• for the formation of the α,α-disubstituted aldehydes. Substrate scope for the photochemical addition of aldehydes to Michael acceptors. Proposed mechanism for the hydroacylation of Michael acceptors using 4-cyanobenzaldehyde (53) as the photoinitiator. Catalytic arylation of aromatic aldehydes by aryl

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• mild electron-rich ligand resulted in hydroacylation product (Scheme 33b) [94]. A plausible mechanism for the hydroarylative cyclization of enynes was shown in Scheme 34. The reaction begins with the reduction of Co(II) to Co(I) by Zn dust. The enyne compound underwent oxidative addition with Co(I) to

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

• Ken Takaki,
• Makoto Hino,
• Akira Ohno,
• Kimihiro Komeyama,
• Hiroto Yoshida and
• Hiroshi Fukuoka

Beilstein J. Org. Chem. 2017, 13, 1816–1822, doi:10.3762/bjoc.13.176

• convert aldehydes to nucleophilic species, which react with activated alkenes to yield hydroacylation products [10][11][12][13][14]. When the carbonyl compounds I other than aldehyde behave similarly, functionalized 1,4-diketones IV would be produced (Scheme 1). Previously, we reported that benzils I (G

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• obtained from the reaction of o-phthalaldehyde (86) with acetophenone 87 (Scheme 28). Iron(III) complexes of 88a–d turned out to be promising candidates for potential photovoltaic or luminescence applications. An intramolecular hydroacylation, catalyzed by nickel(0)/N-heterocyclic carbenes leading to the

• formation of a variety of 1-indanones and 1-tetralones has been proposed by Ogoshi et al. [53]. Thus, hydroacylation of o-allylbenzaldehyde derivatives 89 in the presence of [Ni(cod)2] and the N-heterocyclic carbene with an It-Bu substituent gave 1-indanones 90a–i in high yields (Scheme 29). In the case of

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• . Using a cationic rhodium(I)/QuinoxP* 154 complex, Tanaka and co-workers achieved the enantioselective hydroacylation of α-substituted acrylamides 153 using aliphatic aldehydes 32 to provide 1,4-ketoamides 155 in high yields and excellent enantioselectivity (Scheme 36) [64]. A variety of aliphatic

• cyanation–enantioselective protonation of N-acylpyrroles. Tanaka’s hydroacylation of acrylamides with aliphatic aldehydes. Ellman’s enantioselective addition of α-substituted Meldrum’s acids to terminally unsubstituted nitroalkenes. Ellman’s enantioselective addition of thioacids to α,β,β-trisubstituted

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• ]. Remarkably, the competing hydroacylation reaction was not observed under these reaction conditions. A variety of aliphatic and aromatic aldehydes functioned as acyl donors, whereas several α-ketoesters could be employed as the electrophilic coupling partner to afford the desired products in moderate to good

Metal-free aerobic oxidations mediated by N-hydroxyphthalimide. A concise review

• Lucio Melone and
• Carlo Punta

Beilstein J. Org. Chem. 2013, 9, 1296–1310, doi:10.3762/bjoc.9.146

• role of these initiators in promoting the formation of PINO, performing several selective transformations under aerobic or anaerobic conditions. The combination of NHPI with tiny amounts of dibenzoyl peroxide (BPO) under an atmosphere of argon led to the hydroacylation of simple alkenes by addition of