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We demonstrated the intermolecular [2+2+2] cycloaddition of aryl- and trifluoromethyl-substituted internal alkyne and ethyl cyano­formate, and succeeded in constructing the pyridine derivatives using the CoI2/dcype/Zn catalyst system. The reaction proceeded with a high regioselectivity, and two trifluoromethyl-substituted ethyl picolinate derivatives were obtained as a single regioisomer.

Difluoromethylated oxazolidines and 2-imidazolines were synthesized regioselectively by the reaction of 2-(difluoromethyl)-1-tosylaziridine with various aldehydes or nitriles in the presence of silver(I) hexafluoroantimonate or titanium(IV) fluoride, respectively.

The direct arylation of furans at a sterically congested C−H bond are accomplished. Although there are many methods for catalytic C−H arylation, direct C−H arylation at bulky reaction sites is one of the most problematic issues in this area. In this study, we found that a PdCl2-1,2-bis(dicyclohexylphosphino)ethane (dcype) or PCy3 and silver salt system enables arylations at a sterically congested C−H bonds to produce “highly congested” and “very congested” triarylfurans.

The copper-catalyzed regioselective intermolecular hydroamination of the aryl and trifluoromethyl group or electron-withdrawing group substituted internal alkynes with amines has been accomplished. The reaction was effectively catalyzed by the ligand-free Cu(OTf)2 and afforded the intended amine derivatives in good yields after treatment of NaBH3CN.

A concise two one-pot synthesis of WIN 64821, eurocristatine, 15,15'-bis-epi-eurocristatine, ditryptophenaline, ditryptoleucine A, WIN 64745, cristatumin C, asperdimin, naseseazine A, and naseseazine B is detailed, based on a unique bioinspired dimerization reaction of tryptophan derivatives in aqueous acidic solution and a one-pot procedure for the construction of diketopiperazine rings. Total yields of these alkaloid syntheses were from 10 up to 27 %. In addition, 1'-(2-phenylethylene)-ditryptophenaline was synthesized by using three one-pot operations. The studies detailed herein provided synthesized natural products for inhibitory activities of ubiquitin-specific protease 7 (USP7) and foam cell formation in macrophages. The newly listed biological evaluation for tryptophan-based dimeric diketopiperazine alkaloids discovered 15,15'-bis-epi-eurocristatine, 1'-(2-phenylethylene)-ditryptophenaline, and WIN 64745 as new drug candidates.

A series of 6,13-diamino-substituted pentacenes 1 a-d has been prepared and characterized as a new class of pentacene derivatives with strong donor ability and enhanced solubility in common organic solvents. The spectroelectrochemical and DFT studies revealed that the two-electron oxidation process was accompanied by the substantial structural change into a butterfly-like conformation of the pentacene moiety. More importantly, the extent of deformation from the planar pentacene moiety in the dications of 6,13-diaminopentacene is tunable by varying the N-substituents.

The synthesis and reactions of 3,4-benzo-1,2-disilacyclobut-3-enes and benzo[1,2:4,5]bis(1,2-disilacyclobut-3-ene)s developed by our group are reported in this review. The palladium-, platinum- and nickel-catalyzed reactions of benzodisilacyclobutenes and benzobis(disilacyclobutene)s with unsaturated compounds afford various types of products. The structures of the products are dependent upon the nature of the transition metal used as a catalyst. The reactions of cis- and trans-benzodisilacyclobutenes with alkenes and alkynes in the presence of a transition-metal catalyst proceed with high stereospecificity to give the respective adducts. The thermal reactions of cis- and trans-benzodisilacyclobutenes with various substrates also proceed stereospecifically to give adducts. The results of theoretical calculations for the platinum-catalyzed reaction of disilacyclobutene with acetylene, the nickel-catalyzed reaction of benzodisilacyclobutene and the thermal reaction of benzobis(disilacyclobutene) are discussed in this review.

Recent developments of crystalline Mo3VOx catalysts (MoVO), a new type of oxidation catalysts for selective oxidations of ethane to ethene and of acrolein to acrylic acid, are reviewed. MoVO are formed by the building unit assembly of polyoxomolybdates under hydrothermal conditions. These catalysts are composed of a network arrangement based on a {Mo6O21}6− pentagonal unit and a {MO6} (M = Mo, V) octahedral unit to form a hexagonal channel and a heptagonal channel. Between these channels, the heptagonal channel acts as a micropore of 0.40 nm in diameter which can adsorb small molecules such as CO2, N2, methane, ethane, etc. The size of the heptagonal channel micropore is reversibly and continuously tunable by redox treatment. Interestingly, the heptagonal channel activates ethane inside and acrolein on the channel located over the external surface. Tuning of the heptagonal channel size significantly modifies the catalytic performance for the selective oxidation of ethane. Strong relationships among crystal structure, microporosity, and catalytic performance were observed here.

Chiral piperidines which contain an alkyl group at C4 positions are one of the important architectures because it is appeared in several natural products. An efficient protocol for the preparation of C4-alkyl substituted chiral piperidines using secondary amine catalyzed formal aza [3+3] cycloaddition reaction with aliphatic α,β-unsaturated aldehydes and thiomalonamate derivatives is reported. In our reaction system, thiomalonamate is an excellent nucleophile and the addition of suitable acid and its amount is an important factor for the acceleration effect in organocatalytic reaction. Furthermore, water and MeOH also have an acceleration effect. These efforts lead to only 0.1 mol % catalyst loading in multigram scale synthesis for suitable reaction time. In addition, the efficient enantioselective total synthesis of (+)-α-skytanthine by using our developed reaction as key step was achieved in total 15 % yield. All carbon and nitrogen units were introduced by one step with high enantioselectivity.

Over the last decade, several excellent enantioselective total syntheses of important alkaloids using asymmetric reactions mediated by chiral secondary amine organocatalysts as a key step have been accomplished. This perspective article examines the full strategies of these alkaloid syntheses, especially the application of the organocatalytic reaction to construct the alkaloid scaffolds.

N-Tosyl-2-(difluoromethyl)aziridine was easily prepared from p-toluenesulfonamide (TsNH2) and β-(difluoromethyl) vinyl sulfonium salt in excellent yield. The reaction of the aziridine and a wide range of indoles in the presence of Et2Zn proceeded smoothly to give the corresponding difluoromethyl-β-tryptamine analogues in good to excellent yields and with excellent regioselectivity.

A tartaric acid derivative catalyzes the conjugate addition of diboron (III) to α,β-unsaturated ketones with moderate to good enantioselectivities.

The title compound (δ ≈ 0.08) is hydrothermally synthesized from a mixture of NaF, MoO3, MoO2, guanidinium carbonate, and HF in H2O (autoclave, 160 °C, 3 d).

Tetraarylfurans are highly efficiently obtained starting with a formal [3+2]-cycloaddition of various widely available styrenes and bromo keto esters affording diaryl-substituted dihydrofurans followed by oxidation to give diarylfurans and sequential arylations.

The synthesis and reactions of silacyclopropenes are summarized. Addition of silylenes to acetylenes and photochemical isomerization of alkynyldisilanes are known as two major routes for the synthesis of silacyclopropenes. Silacyclopropenes had been thought to be highly reactive and difficult to handle until the first crystal structure of a stable one was reported in 1980. Currently, however, it is commonly accepted that those molecules are stable under ambient conditions when sufficiently bulky substituents are introduced onto the strained three-membered ring system to stabilize it kinetically. The reactivity of silacyclopropenes is interesting and depends on the nature of substituents. They, indeed, undergo a variety of reactions, such as photolysis, thermolysis, and transition-metal-catalyzed reactions, leading to the formation of reactive intermediates including silylenes and silapropadienes, and their transition-metal complexes, through which numerous transformations into silicon-containing cyclic and acyclic compounds are possible.

Zero-valent nanoporous gold is shown to be a robust and green heterogeneous catalyst for α-C—H functionalization of various tertiary amines.

A new class of C2 chiral materials was easily prepared by the photodimerization reaction of (R)-N-phenethyl-2-chromonecarboxamide followed by recrystallization. Reduction of the photodimer gave the corresponding alcohol stereoselectively. Both C2 chiral materials worked effectively as ligands for enantioselective ethylation of arylaldehydes using diethylzinc.

The title reaction proceeds through a radical addition, followed by a ring closure process.

2-Vinyl-substituted phenol and an alpha-bromoester undergo a tandem esterification–alkylation reaction in the presence of a Cu–amine catalyst system to produce benzene-fused lactone. Z-Alkylated styrene is obtained after hydrolysis of the lactone with perfect selectivity. The simple protocol developed in this work opens a new avenue in the multi-substitution chemistry of alkenes.

The synthesis, and spectroscopic and magnetic properties of quadruple-decker phthalocyanines (Pcs) have been reviewed. While the presence of stacked mercury Pc oligomers was proposed as early as 1992, the isolation of a quadruple-decker Pc was first achieved in 2010. Herein, we review how the synthetic strategy for quadruple-decker Pcs has come to be conceived from the recent development of cadmium Pc oligomers, which will be followed by illustration of unique physicochemical properties originating from the structure of the quadruple-decker frameworks. In the spectroscopy section, the electronic structures of the quadruple-decker Pc are discussed based on the theoretical and experimental results. A simple molecular orbital (MO) method predicts that energy gaps among the occupied frontier MOs of the quadruple-decker Pc become smaller than those of double- or triple-decker Pcs, leading to the observation of exceptionally low-lying electronic transitions for the oxidized quadruple-decker Pcs. It has been confirmed that the corresponding lowest π–π* electronic transitions reach the infrared region for the one-electron oxidized quadruple-decker Pcs. In the magnetic property section, a clear evidence of the long-range magnetic dipole–dipole f–f interactions between two f-electronic centers of diterbium quadruple-decker Pc is provided, and its magnetic relaxation phenomena arising mainly from quantum tunneling magnetizations (QTMs) will be discussed by using the alternate current (ac) magnetic susceptibility data, and the numerically calculated Zeeman diagram of the f-electronic centers in the quadruple-decker Pc.

We demonstrate the first preparation of difluoromethyl (CF2H) vinyl sulfonium salt as a new difluoromethylated building block, followed by its application to the synthesis of CF2H-containing cyclopropanes in one step. The salt itself is readily prepared from 3-bromo-3,3-difluoropropene in three steps, in high overall yields, and is stable. A wide range of active methylene compounds participated in the cyclopropanation reaction using this salt, providing the corresponding products in high-to-excellent yields.

There are a few reports on the reaction of tertiary alkyl halide and alkene to produce an alkyl-substituted alkene. To establish tertiary alkylation of a C–C double bond, radical reaction is found to be one of the most promising protocols. In this paper, we highlight tertiary alkyl substitutions on C–C double bonds via atom-transfer radical substitution (ATRS) catalyzed by a copper salt and introduce the corresponding M–H reactions. 1 Alkylation via the Mizoroki–Heck Reaction 2 Tertiary Alkylative M–H-Type Reaction 3 Regioselective Double-Bond Formation 4 Summary and Perspectives

In this study, for distal-selective β-hydride elimination to produce exomethylene compounds with a newly formed Csp3–Csp3 bond between tertiary alkyl halides and α-alkylated styrenes, a combination of a Cu(I) salt and a pyridine-based amine ligand (TPMA) is found to be a very efficient catalyst system. The yields and regioselectivities were high, and the regioselectivity was found to be dependent on the structure of the alkyl halide, with bulky alkyl halides showing the highest distal selectivities.

The title reaction affords the corresponding trifluoromethyl group substituted benzene derivatives in high yield with excellent selectivity.

The diastereo- and enantioselective formation of 3-arylaziridine-2-carboxylates from aryl aldehydes and guanidinium ylides is investigated.

The reaction of (I) and aliphatic alkenes other than (IIf), such as hex-1-ene, methyl acrylate, and ethenyl acetate, yields the corresponding cyclopropanated products in trace amounts only.

The title compounds (V) are efficiently obtained in a two-step procedure starting from readily available aryl(2-bromophenyl)methanones (I).

The asymmetric total synthesis of hedyotol A is accomplished via proline-catalyzed aldol reaction and the use of a quinomethide intermediate for the furofuran skeleton construction.

The nanoporous AuPd (AuPdNPore) alloy catalyst showed superior chemoselectivity and high catalytic activity for the direct 1,4-hydrosilylation of the conjugated cyclic enones with hydrosilane in comparison with the monometallic nanoporous Au and Pd catalysts. The enhanced catalytic properties of AuPdNPore arise mainly from the nanoporous structure and the synergistic effect of the AuPd alloy.

The synthesis of title compound (I) is achieved via the asymmetric Michael reaction of pentanyloxyacetaldehyde with nitroethenylacetamide as the key step in seven steps and 36% overall yield.

The IKM-159 (XVI) and analogues [(VIII) and (XV)] in racemic form are synthesized via Ugi/Diels-Alder and metathesis reaction with high level of regiocontrol.

A one-pot transformation of aldehydes into α,β-unsaturated aldehydes was developed using both N-benzyl-N-methylamine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as catalysts and MnO2 as a terminal oxidant. An oxidative and enantioselective reaction of aldehydes and nitromethane was established using both diphenylprolinol silyl ether and DDQ as a catalyst with MnO2 as a terminal oxidant, in which synthetically important β-substituted γ-nitro aldehydes were obtained with excellent enantioselectivity.

Guanidines can act as ligands for various organic and inorganic ions. We have previously synthesized polymer-supported aromatic bisguanidine derivatives and evaluated their potential for removing arsenic from polluted water. In this work, we designed and synthesized the corresponding aliphatic bisguanidine derivatives, and we demonstrated that they show greater affinity for arsenic acid than do the previous aromatic ligands. The newly synthesized HypoGel resin-anchored aliphatic bisguanidines might serve as useful recyclable scavengers for the removal of arsenic from polluted water.

Tryptophan-based dimeric diketopiperazine alkaloids such as ditryptophenaline, WIN 64821, naseseazine A, and naseseazine B, exhibit a unique architecture and interesting biological activity. These alkaloids have been the subject of intense study by the synthetic organic chemistry community, and several elegant total syntheses have been discovered, especially using bioinspired strategies. Described herein is a brief overview of these alkaloid syntheses via bioinspired transformations as key steps.

A novel catalytic property of nanoporous gold for activation of bis(pinacolato)diboron has been reported that allows the direct diboration of alkynes to proceed sufficiently in a heterogeneous process. The experimental results revealed that the nanoporous gold catalyst is able to cleave the B–B bond of bis(pinacolato)diboron without using any additives.

The term ‘super base’ is generally applied to ionic metal-containing bases that undergo irreversible proton abstraction. However, non-ionic powerful amine derivatives of amidines, guanidines, phosphazenes, and Verkade’s bases with comparable or higher basicity to that of 1,8-bis(dimethylamino)naphthalene can all be arbitrarily classified as organic superbases. This Cluster contains manuscripts that present recent progress on organic superbases, including their applications in organic synthesis but, before proceeding, let us consider what class of molecule constitutes an organic superbase.

Here we report total synthesis of enantiomerically pure dysibetaine CPa, isolated from Micronesian marine sponge and expected to serve as a neuroactive agent. Starting from meso-cyclopropane triester, the synthesis was achieved in 12.8% overall yield over 10 steps including organocatalytic enantioselective solvolysis of meso-succinic anhydride as a key step. This work established the absolute configurations of the natural product as (3R,4R).

Easy as 1,2,3: Reaction of methyl carbamate, triethyl orthoformate, and readily available alkenes provides a highly practical preparation of protected aminocyclopropanes. The reaction proceeds with preferential cis addition to alkenes, and cleavage of the methyl carbamate gives the free aminocyclopropanes as their HI salts.

The Ugi reaction is a useful four-component coupling reaction for α-(acylamino)amide. However, selective transformation of the two amides is generally difficult. Here, we report 1-hydroxy-2-methyl-2-propyl isocyanide (HMPI) as a new member of a ‘convertible isocyanide’ class used to solve the problem. HMPI is odorless and shows good reactivity in the Ugi reaction to give N -(1-hydroxy-2-methyl-2-propyl) amides, which are smoothly converted into esters upon Zn(OTf) 2 -mediated solvolysis. Overall, structurally diverse α-amino acid esters are readily accessible in two steps by using HMPI.

Photochemical treatment of enyne compounds of type (I) with large excess of disulfide results in convenient and stereoselective formation of pyrrolothiophene derivatives which are of biological interest.

Unlike Fe3O4 which only catalyzes the coupling of nitroalkanes, CuFe2O4 nanoparticles catalyze both the oxidative coupling of aromatic alkynes and nitroalkanes with tetrahydroisoquinolines.

The intramolecular anionic Diels—Alder reaction of diynes (I) and (III) affords arylnaphtalene lignans which are valuable precursors for the synthesis of natural products.