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A novel approach for the synthesis of 1,1,4,5-tetrasubstituted phthalans is developed via a tandem palladium-catalyzed Sonogashira coupling/propargyl-allenyl isomerization/pentadehydro-Diels-Alder cyclization/regioselective nucleophilic addition sequence. The reaction shows good functional tolerance and provides a wide variety of substituted phthalans in moderate to high yields from haloarenes, triynes, and protic nucleophiles, such as amines and alcohols, under very mild conditions.

Cucurbit[7]uril (CB[7]) is a supramolecular binding host for peptides and proteins with N-terminal Phe. However, the low occurrence of such peptides and proteins limits broader applications of this unique host-guest interaction. Here, we report a strategy to expand the scope of CB[7]-peptide interaction by site-specifically introducing N-terminal substitutions (e.g. benzyl groups) using reductive alkylation. N-terminal benzylated peptides have similar affinity to CB[7] as native peptides with N-terminal Phe and even stronger interactions can be achieved using better ligands. We further expanded this host-guest interaction to be stimuli responsive. By introducing benzyl carboxylate substituents, the CB[7]-peptide interaction shows pH-dependent binding. Furthermore, benzyl boronate substituents led to saccharide-dependent CB[7]-peptide interactions. We demonstrated that using this strategy to introduce stronger CB[7] binders to the N-terminus of human calcitonin (hCT) results in increased aggregation stability in the presence of CB[7]. This strategy to expand CB[7]-peptide interaction scope opens opportunities for future applications in peptides and proteins.

Aspidodasycarpine and lonicerine are a pair of epimeric aspidophylline-type alkaloids bearing vicinal quaternary C7 and C16. The first and enantioselective total syntheses of these molecules are described here. A Ru-catalyzed asymmetric transfer hydrogenation established the first stereocenter. An Au-promoted Toste cyclization was exploited to assemble the bridged tetracyclic core and define the geometry of the exocyclic olefin; electron deficient (p-CF3C6H4)3P was a suitable ligand for this transformation. An aldol condensation followed by an intramolecular indole C3 alkylation constructed the adjacent quaternary C7 and C16 diastereoselectively, leading to a pentacyclic lactol as an advanced common intermediate for synthesizing both alkaloids. The proposed structure of lanciferine, a highly oxidized congener of aspidodasycarpine, was synthesized from the lactol by tuning the oxidation states of various carbons.

A cationic gold(I)-catalyzed decarboxylative etherification of propargyl carbonates to selectively produce propargyl ethers is reported. In the reaction the gold(I) catalyst shows a distinct σ-Lewis acidity rather than the commonly observed π-Lewis acidity, and thus catalyzes the decarboxylation of a variety of propargyl carbonates to give the corresponding propargyl ethers with high selectivity. This reaction represents a rare example of the tunable reactivity of cationic gold(I) complexes between σ-Lewis acidity and π-Lewis acidity.

A gold-catalyzed cyclization of 3-(2'-azidoaryl)-1-arylpropargyl carbonates to generate substituted quinolines via a sequence of 3,3-rearrangement, 6-endo-trig cyclization and denitrogenation has been developed. Similar products could be obtained from 3-aryl-1-(2'-azidoaryl)propargyl carbonates under different gold catalytic conditions via a sequential 6-endo-dig cyclization, denitrogenation, and 1,2-H shift process.

Trioxacarcins DC-45-A2, DC-45-A1, A, D, C7″-epi-C, and C have been synthesized through stereoselective strategies involving BF3·Et2O-catalyzed ketone-epoxide opening and gold-catalyzed glycosylation reactions, and the full structural assignment of trioxacacin C was deciphered via the syntheses of both of its C7″ epimers. The gathered knowledge sets the foundation for the design, synthesis, and biological evalution of analogues of these natural products as potential payloads for antibody-drug conjugates and other delivery systems for targeted and personalized cancer chemotherapy.

In this paper, we report a novel sequential reaction sequence consisting of a series of processes including Sonogashira coupling, propargyl-allenyl isomerization, [3 + 2] cycloaddition, denitrogenation, and highly selective biradical coupling reaction, providing an efficient synthesis of fused polycyclic pyrrole derivatives. The reaction features one C-C bond and two C-N bonds formed to construct the pyrrole unit, together with two rings efficiently assembled in one stroke.

In the catalyzed decarboxylative etherification of propargyl carbonates the gold(I) catalyst shows a distinct σ-acidity and propargyl ethers are furnished.

An interesting sequential reaction consisting of Sonogashira coupling, propargyl–allenyl isomerization, allenyl–benzyl Claisen rearrangement and [4 + 2] cycloaddition was developed. This reaction provides an efficient synthesis of fused tricyclo[3.2.1.02,7]oct-3-enes.

A gold-catalyzed cyclization of 3-(2′-azidoaryl)-1-arylpropargyl carbonates to generate substituted quinolines via a sequence of 3,3-rearrangement, 6-endo-trig cyclization and denitrogenation has been developed. Similar products could be obtained from 3-aryl-1-(2′-azidoaryl)propargyl carbonates under different gold catalytic conditions via a sequential 6-endo-dig cyclization, denitrogenation, and 1,2-H shift process.

A novel Pd-catalyzed sequential reaction for the synthesis of fused tricyclic compounds with a dihydrofuran or isobenzofuranone unit was developed.

We describe a total synthesis of (±)-chlorovulone II that is 10 steps shorter than the best alternative currently available (nine vs 19 steps). The key event of the synthesis is an aldol addition of the enolate of ethyl acetate into 4-cyclopentene-1,3-dione, a substance that has received little attention as an educt for prostanoid synthesis and for which little is known about carbonyl 1,2-addition with enolates. In addition, we provide chemical and stereochemical details of a route to a key intermediate toward the title compound that involves a carbonyl−ene reaction and a radical addition to an aldehyde carbonyl.

A catalytic ene-like reaction of aldehydes with those vinyl ethers that display the oxygen functionality at the central carbon of an allylic system, e.g., 2-methoxypropene, is discussed in detail. The reaction is promoted by 0.05 equiv. of the 1:1 complex of Yb(fod)3 and acetic acid, and it is forms the centerpiece of our synthesis of chlorovulone II, mitomycinoids and phyllanthocin.

A highly efficient, facile, and mild synthesis of the title compounds is developed from easily available starting materials.

We report in this paper an interesting sequential reaction involving sequential Sonogashira coupling, propargyl–allenyl isomerization, [4 + 2] cycloaddition and aromatization reaction, which provides a facile method for the synthesis of a variety of polycyclic isoindoline derivatives from easily accessible starting materials.

A convenient sequential method for the facile and efficient synthesis of the title compounds (II) and (IV) from easily accessible starting materials is developed under mild conditions.

Homo-Michael addition of Li selenolates to cyclopropyl ketones and subsequent reaction with electrophiles leads to allenyl or alkynyl ketones or furans.

A catalytic ene-like reaction of aldehydes with those vinyl ethers that display the oxygen functionality at the central carbon of an allylic system, e.g., 2-methoxypropene, is discussed in detail. The reaction is promoted by 0.05 equiv. of the 1:1 complex of Yb(fod)3 and acetic acid, and it is forms the centerpiece of our synthesis of chlorovulone II, mitomycinoids and phyllanthocin.

We describe a total synthesis of (±)-chlorovulone II that is 10 steps shorter than the best alternative currently available (nine vs 19 steps). The key event of the synthesis is an aldol addition of the enolate of ethyl acetate into 4-cyclopentene-1,3-dione, a substance that has received little attention as an educt for prostanoid synthesis and for which little is known about carbonyl 1,2-addition with enolates. In addition, we provide chemical and stereochemical details of a route to a key intermediate toward the title compound that involves a carbonyl−ene reaction and a radical addition to an aldehyde carbonyl.

In this paper, we report a novel sequential reaction sequence consisting of a series of processes including Sonogashira coupling, propargyl-allenyl isomerization, [3 + 2] cycloaddition, denitrogenation, and highly selective biradical coupling reaction, providing an efficient synthesis of fused polycyclic pyrrole derivatives. The reaction features one C-C bond and two C-N bonds formed to construct the pyrrole unit, together with two rings efficiently assembled in one stroke.

An interesting sequential reaction involving Pd-catalyzed coupling, propargyl−allenyl isomerization, and Alder−ene cycloaddition is reported, providing a facile synthesis of some not readily available 2,3-dihydrofurans from electron-deficient vinyl or aromatic halides and 1-aryl-prop-2-ynyl 3′-methylbut-2′-enyl ethers.

A novel Pd-catalyzed sequential reaction for the synthesis of fused tricyclic compounds with a dihydrofuran or isobenzofuranone unit was developed.

A series of dicationic porphyrins were found to specifically recognize loop structures of oligodeoxynucleotides, and to selectively oxidize guanine residues upon photo-irradiation at micromolar concentrations. These compounds could, thus, be employed as promising structural probes for specific secondary DNA structures. The production of singlet oxygen ((1)O2) is responsible for the DNA-modification profiles. Both UV-titration and thermal-melting experiments indicate that the strong affinity of the charged porphyrins towards DNA loops is responsible for these molecular-recognition phenomena.

A homo-Michael addition reaction of lithium selenolates with 1-(1-alkynyl)cyclopropyl ketones and the subsequent reaction with electrophiles such as PhSeBr, NFSI and NCS is reported. Based on the nature of electrophiles, this reaction may afford highly substituted 1,2-allenyl ketones or furans (E(+) = PhSe(+)) and 2-alkynyl ketones (E(+) = F(+), Cl(+), active halides) as the final products, respectively.

We report in this paper an interesting tandem reaction involving sequential palladium(0)-catalyzed decarboxylation of diynylic carbonates, intramolecular nucleophilic cyclization and Schmittel reaction, which provides a facile method for the synthesis of a variety of polycyclic benzo[b]fluorene derivatives from easily accessible starting materials.