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The C-H alkylation of benzyl alcohols with α-ketoacid derivatives was achieved in the presence of thiobenzoic acid with or without Ru or Ir photoredox catalysts. The thiobenzoic acid serves as a photoexcited single-electron reducing reagent and a hydrogen atom transfer catalyst, while addition of the metal photoredox catalyst assists the electron transfer and improves the reaction efficiency. Various functional groups were tolerant of the reaction conditions, and sterically hindered diols were produced in good to high yield.

Asymmetric electrophilic fluorination of difluoroalkenes remains undeveloped because of the poor reactivity of difluoroalkenes with electrophiles. However, such reactions, if feasible, are expected to be useful for the synthesis of chiral heterocyclic compounds with a trifluoromethyl group at the stereogenic center. In this Letter, we disclose the first example of asymmetric fluoroamide cyclization of difluoroalkenes using our dianionic phase-transfer catalyst. This reaction provides unique chiral trifluoromethylated oxazoline derivatives at a synthetically useful level.

Asymmetric dearomatizing fluorocyclization of indole derivatives was investigated using a dicarboxylate phase-transfer catalyst. This reaction proceeds under mild reaction conditions to provide fluoropyrroloindoline derivatives in a highly enantioselective manner. Various substitution patterns on the indole ring are well tolerated. To facilitate the reaction and ensure reproducibility, the addition of water is essential, and its possible role is discussed.

Aliphatic C-H fluorination of phthalimide derivatives with Selectfluor was investigated under photoirradiation conditions. The reaction did not require any additive or catalyst and afforded C-H fluorinated products in moderate to good yields. It is likely that the reaction site depends on the C-H bond energy, and this may be the reason for the good to high regioselectivity.

Photoenols generated in situ from ortho-methyl-substituted phenylketones such as benzophenones and acetophenones were trifluoromethylated with Togni reagent without any additive or catalyst. This trifluoromethylation reaction proceeded smoothly under photoirradiation conditions (365 nm). Various functional groups were tolerant of the reaction conditions. Interestingly, the trifluoromethyl group was exclusively introduced at the ortho-benzylic position. Mechanistic studies suggested that this reaction proceeds via formation of a photoenol, not via a radical pathway.

An efficient total synthesis of TAN1251C was accomplished by employing a Ugi four-component accumulation reaction and a Dieckmann condensation to construct the spiro-fused cyclohexanone and γ-lactam ring. Diastereoselective reduction by side-chain-controlled hydrogenation of enamide 15 or Zn reduction of oxime 23 enabled construction of the amino group with the desired stereochemistry.

The cyclopentane core framework 23 of pactamycin (1) was synthesized in 14 steps from symmetric cyclohexadiene 11. Our synthetic strategy features Rh-mediated catalytic desymmetrization of 10 via aziridination and then regioselective ring-opening reaction of sulfonylaziridine 9 with NaN 3 , ring-contraction of cyclohexene 14 by ozonolysis followed by intramolecular aldol reaction, and stereoselective construction of the sequential tetrasubstituted carbons by dihydroxylation and methylation reaction. Stereospecific incorporation of amine on tetrasubstituted carbon was achieved by Curtius rearrangement and subsequent carbamide formation.

A highly enantioselective bromocyclization of allylic amides with N-bromosuccinimide (NBS) was developed with DTBM-BINAP as a catalyst, affording chiral oxazolines with a tetrasubstituted carbon center in high yield with up to 99% ee. By utilizing the bromo substituent as a handle, the obtained compounds were converted to synthetically useful chiral building blocks.

The total synthesis of hedyotol A (1), a natural product isolated from Hedyotis lawsoniae (DC.) Wight et Arn. (Rubiaceae), was accomplished in a highly stereocontrolled manner. Key steps include an L-proline-catalyzed cross-aldol reaction and the biomimetic construction of a furofuran lignan skeleton through a quinomethide intermediate.

Practical total syntheses of acromelic acids A (1) and B (2), which have potent neuro-excitatory activity, were accomplished in 13 (36% total yield) and 17 steps (6.9% total yield), respectively, from 2,6-dichloropyridine (8). Regioselective transformation of symmetric 8 provided nitroalkenes 15 and 16. The pyrrolidine ring was efficiently constructed by Ni-catalyzed asymmetric conjugate addition followed by intramolecular reductive amination.

A practical total synthesis of kainoid MFPA (5) was achieved in only six steps, via a novel Ni-catalyst-mediated asymmetric conjugate addition reaction. Furthermore, a fluorescein-based fluorescent ionotropic glutamate receptor probe 28 was efficiently synthesized from a precursor derived from a synthetic intermediate of 5.

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).

Asymmetric bromolactonization of prochiral cyclohexadiene derivatives with N-bromosuccimide proceeded in the presence of (DHQD)(2)PHAL as a chiral catalyst to afford the corresponding bromolactones with up to 93% ee. This reaction was also applicable to the kinetic resolution of a racemic cyclic ene-carboxylic acid, where the starting material was recovered with high enantioselectivity.

[reaction: see text] We report here the catalytic asymmetric conjugate reduction of enones using ethanol as a hydride source. The reaction was carried out in the presence of a chiral Pd complex at ambient temperature in ethanol, and the desired products were obtained in high chemical yield and high enantioselectivity. We applied this novel reaction to the catalytic asymmetric synthesis of warfarin (96% ee), and on the basis of d-labeling experiments, the reaction mechanism is proposed.

[reaction: see text] Palladium complexes (1 and 2) were immobilized in ionic liquids, and their applications to catalytic asymmetric fluorination and Michael reaction of beta-ketoesters were successfully demonstrated. This immobilization enabled the reuse of the catalysts no less than 10 times in fluorination and 5 times in Michael reaction with levels of efficiency comparable to those obtained in usual organic solvents.