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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]

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.

A new cleavage reaction of carbon-carbon triple bonds proceeds efficiently with NIS and TMSN3, giving the corresponding nitriles in moderate to good yields.

Covering: 2010-2011. Previous review: Nat. Prod. Rep. 2010, 27, 1630-1680This review covers the literature on simple indole alkaloids and those with a non-rearranged monoterpenoid unit from the beginning of 2010 up to the end of 2011, which includes newly isolated alkaloids, structure determinations, total syntheses and biological activities.

The concise total synthesis of calothrixins A and B has been accomplished by utilizing the one-pot formation of hexatriene as a key intermediate via the palladium-catalyzed tandem cyclization/cross-coupling reaction of triethyl(indol-2-yl)borate. In another key transformation, the indolo[3,2-j]phenanthridine core was prepared in high yield via Cu(I)-mediated 6π-electrocyclization.

The preparation of 2',3'-epimino-carbocyclic analogues of adenosine is reported. The reaction of p-tosyl azide with N-substituted 2-azabicyclo[2.2.1]hept-5-en-3-one (ABH) (1a) provided aziridine-fused ABH (2), which was converted to 2',3'-epimino-carbocyclic nucleosides (11).