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Covering: 2012 to 2013. Previous review: Nat. Prod. Rep., 2013, 30, 694–752 This review covers the literature on simple indole alkaloids and those with a nonrearranged monoterpenoid unit from the beginning of 2012 up to the end of 2013, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities. [ABSTRACT FROM AUTHOR]

Abstract: Investigation of the palladium-catalyzed tandem cyclization-cross-coupling reaction using indolylborate (2) as a transfer agent has been carried out. Furthermore, the cross-coupling reaction performed under carbon monoxide led to the generation of indolyl ketones. [Copyright &y& Elsevier]

Abstract: A novel one-pot protocol for the preparation of cycloalkano[1,2-a]indoles by way of an intramolecular alkyl migration reaction in cyclic indolylborates is described. NaOMe was found to act as a successful trialkylboryl-protecting group against to the lithiation at the C2 of the indole ring. Treatment of cyclic indolylborates with electrophiles produced cycloalkano-[1,2-a]indoles. [Copyright &y& Elsevier]

The intramolecular alkyl migration reaction in indolylborates was developed for the one-pot construction of carbazoles via intramolecular cyclization in which π-allylpalladium complexes were successfully adopted as an acceptor for the indole nucleophile. [Copyright &y& Elsevier]

Studies the palladium-catalyzed carbonylative cross-coupling reaction with triethyl(1-methylindol-2-yl)borate. Indolylborate intermediate; Transformation of borate; Ketone synthesis.

A new cleavage reaction of carbon–carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields. [ABSTRACT FROM AUTHOR]

Cu(I)-mediated dimerization of skatoles (I) provides indoloquinazolinones (II). [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "One-Pot Access to 3,3'-Bisindolylmethanes through the Intermolecular Pummerer Reaction" by M. Ishikura and others published in the periodical "Heterocycles" in 2014.

Review: 265 refs. [ABSTRACT FROM AUTHOR]

Concise and efficient syntheses of various trans-2,3-disubstituted-2,3-dihydro-4-quinolones have been achieved via tandem Hofmann-type rearrangement of 2-alkynylbenza-mides, nucleophilic addition of alcohols to the isocyanate intermediates, intermolecular [2+2]-cycloaddition with carbon--carbon triple bonds and aldehydes, and intramolecular aminocyclization of nitrogen of carbamates to the α/β-unsaturated ketones. [ABSTRACT FROM AUTHOR]

Abstract: Direct, efficient syntheses of the benzimidazo[2,1-a]isoquinoline ring system have been achieved with 2-bromoarylaldehydes, terminal alkynes, and 1,2-phenylenediamines by a microwave-accelerated tandem process in which a Sonogashira coupling, 5-endo cyclization, oxidative aromatization, and 6-endo cyclization can be performed in a single synthetic operation. [Copyright &y& Elsevier]

The syntheses of 2,3-dihydro-4-quinolones from 2-propargylphenylcarbamates by one-pot tandem process that involves Meyer-Schuster rearrangement or arylative Meyer-Schuster rearrangement/Michael addition of carbamate nitrogen to the resulting vinyl ketones have been developed. Phenylcarbamates tethering tertiary propargyl alcohols underwent arylative Meyer-Schuster rearrangement/Friedel-Crafts alkylation to produce 2,3-dihydroindenones. [ABSTRACT FROM AUTHOR]

We developed a concise protocol for the synthesis of ellipticine quinone from the appropriate 3-iodoindole-2-carbaldehydes in four steps. The key step is the construction of carbazole-1,4-quinone through tandem Ring-Closing Metathesis (RCM) and dehydrogenation under oxygen atmosphere. Therefore, the ellipticine quinone analogs possessing substitution at the 8- and/or 9-positions were synthesized using this method. In total, 14 compounds were evaluated for antiproliferative activity against HCT-116 and HL-60 cell lines; 9-nitroellipticine quinone was found to have superior activity compared to calothrixin B. [ABSTRACT FROM AUTHOR]

We report a convenient synthesis of carbazole-1,4-quinone alkaloid koeniginequinones A and B using a tandem ring-closing metathesis with the dehydrogenation reaction sequence under an O 2 atmosphere as an important step. Using this method, carbazole-1,4-quinones substituted at the 5-, 6-, 7-, and/or 8-positions have been synthesized. Moreover, 24 compounds, including koeniginequinones A and B, have been evaluated for their antiproliferative activity against HCT-116 and HL-60 cells, and the 6-nitro analog exhibited the most potent activity against both tumor cell types. [ABSTRACT FROM AUTHOR]

Concise syntheses of 9-methoxyellipticine, 3,4-dihydroellipticine (µ-alkaloid D), 1,2,3,4-tetrahydroellipticine, 2-methyl-1,2,3,4-tetrahydroellipticine, olivacine, 3,4-dihydroolivacine, (±)-guatambuine, and (±)-janetine were developed starting from hexatriene intermediates readily obtained by Pd-catalyzed tandem cyclization/cross-coupling reaction of indolylborates. The route enables the facile construction of pyrido[4,3- b]carbazoles by Cu-catalyzed 6π-electrocyclization and subsequent transformation of the pyridocarbazole intermediates into pyrido[4,3- b]carbazole alkaloids. [ABSTRACT FROM AUTHOR]

A new approach to form iminoisocoumarins from readily available and stable 2-alkynylbenzamides was developed by using a tandem copper-catalyzed N-arylation and regioselective 6- endo- dig cyclization in the presence of diaryliodonium salts, a copper catalyst, and 2,6-di- tert-butylpyridine. The arylation occurred at the nitrogen atom rather than the oxygen atom of the amide group, the alkynyl carbon, or the benzene ring of the benzamide. Cyclization occurred through a preferential nucleophilic attack by the oxygen rather than the nitrogen atom of the amide group to produce iminoisocoumarin derivatives in good to moderate yields. [ABSTRACT FROM AUTHOR]

Abstract: A novel one-pot synthesis of carbazole-1,4-quinone by consecutive Pd-catalyzed cyclocarbonylation, desilylation, and oxidation reactions is described. We propose a possible mechanism of the cyclocarbonylation reaction between 3-iodo-2-propenylindole and CO (1 atm) in the presence of a tributyl(vinyl)tin and Pd-catalyst and the resulting acylpalladium species was directly coupled with a terminal alkene to produce the carbazole-1,4-quinone. To our knowledge, this is the first example of this type of reaction. A new formal total synthesis of a carbazole-1,4-quinone alkaloid, murrayaquinone A was established using this reaction. [Copyright &y& Elsevier]

Abstract: 9,10-Phenanthrenequinone (9,10-PQ) is one of the most abundant quinones among diesel exhaust particulates. Recent data have suggested that quinones induce apoptosis in immune, epithelial and tumor cells, leading to respirator illness; however, the mechanisms by which quinones induce apoptosis and the structure required for this remain unknown. We studied the antitumor activity of 9,10-PQ analogs against two human tumor cell lines, HCT-116 colon tumor cells and HL-60 promyelocytic leukemia cells. The loss of the cis-orthoquinone unit in 9,10-PQ abrogated its ability to induce apoptosis in the two tumor cell lines, and the LC50 values of these analogs were indicated over 10μM. An analog of 9,10-PQ in which the biaryl unit had been deleted displayed a reduced ability to induce tumor cell apoptosis, while the analogs 1,10-phenanthroline-5,6-dione (9) and pyrene-4,5-dione (10), which also had modified biaryl units, exhibited increased tumor cell apoptotic activity. The cis-orthoquinone unit in 9,10-PQ was identified as essential for its ability to induce apoptosis in tumor cells, and its biaryl unit is also considered to influence orthoquinone-mediated apoptotic activity. [Copyright &y& Elsevier]

A one-pot approach to 3,3′-bisindolylmethane derivatives from nitrobenzene derivatives through the Bartoli indole synthesis was developed, in which the acid used to quench the reaction markedly affected its outcome. Quenching the reaction with concd HCl produced 3,3′-bisindolylmethane in contrast to the formation of 7-substituted indole by quenching with NH4Cl. [ABSTRACT FROM AUTHOR]

( S)-(-)-Dichotomine A and its enantiomer were synthesized from the key intermediate, methyl 1-(1-hydroxyethyl)-β-carboline-3-carboxylate, by enantioselective esterification with Lipase QLM. The first total synthesis of (+)-dichotomide II and its enantiomer were also achieved from ( S)-(-)-dichotomine A methyl ester and its enantiomer. The absolute configuration of the stereogenic center of the reported (+)-dichotomide II was determined to be R. [ABSTRACT FROM AUTHOR]

The palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate with vinyl bromide was successfully used in the concise total synthesis of the indolophenanthridine alkaloids, calothrixins A and B. [ABSTRACT FROM AUTHOR]

Abstract: A new entry to the total synthesis of isocryptolepine (cryptosanguinolentine), isolated from Cryptolepis sanguinolenta, was achieved by constructing a tetracyclic ring system through a microwave-assisted tandem Curtius rearrangement and electrocyclic reaction of an aza 6π-electron system. The tetracyclic lactam was converted to isocryptolepine in a four-step sequence. [Copyright &y& Elsevier]

Starting from ortho-alkynylbenzaldehydes and ortho-alkynylanilines, In(OTt)3-catalyzed synthesis of ring-condensed heteroaromatic compounds was developed via a domino intramolecular nucleophilic attack/intermolecular cycloaddition/dehydration reaction. [ABSTRACT FROM AUTHOR]

A one-pot approach to indolo[2,1- b ]quinazolines from indole-3-carbaldehydes through the Dakin oxidation was developed. It was shown that the reaction proceeded through the condensation of indole-3-carbaldehydes with isatoic anhydrides, derived in situ from indole-3-carbaldehydes by the Dakin oxidation, and further oxidation/cyclization steps. [ABSTRACT FROM AUTHOR]

Abstract: We synthesized calothrixin B using our developed biomimetic method and derived N-alkyl-calothrixins A and B. The in vitro antimalarial activity of the calothrixin derivatives, including calothrixins A and B, against the Plasmodium falciparum FCR-3 strain was evaluated. All test compounds exhibited antimalarial activity over a concentration range of 6.4×10−6–1.2×10−7 M. [Copyright &y& Elsevier]

Cu-catalyzed 6π-electrocyclization of triene-substrates of type (I) provides a facile access to pyrido[4,3-b]carbazoles, which represent advanced intermediates for the construction of various ellipticine and olivacine alkaloids. [ABSTRACT FROM AUTHOR]

affording a series of iminoisocoumarins [ABSTRACT FROM AUTHOR]

The alkaloid tryptanthrin (IIa) is further converted into the natural products phaitanthrin A (IXa), phaitanthrin B (IXb), and cruciferane (X). [ABSTRACT FROM AUTHOR]

3-Iodo-2-propenylindoles (I) are easily prepared from corresponding indole-2-carbaldehydes and vinyl Grignard reagents. [ABSTRACT FROM AUTHOR]

The synthesis of a wide variety of bisindolylmethanes is achieved via reaction of nitromethanes with vinylmagnesium bromide, followed by quenching with HCl or reaction with aldehydes. [ABSTRACT FROM AUTHOR]