Sexannulate Orobdella leech, Orobdella ijimai, is redescribed based on newly collected specimens from the type locality, Nikko, Tochigi Pref., Japan, since this species was originally described based on limited number of characters. In addition, two new sexannulate species, Orobdella dolichopharynx sp. nov. from Amamioshima Island in the Ryukyu Archipelago, Japan, and Orobdella shimadae sp. nov...

Phosphotungstic acid (H(3)PW(12)O(40)) was used as an efficient and recyclable catalyst for the synthesis of polysubstituted quinolines through the Friedländer condensation of 2-aminoarylketone with carbonyl compounds, which was achieved by conventional heating under solvent-free conditions.

The dimetallic [M(2)(bpy)(2)(NO(3))(2)](NO(3))(2) moieties (M = Pd(II) or Pt(II)) react preferentially at the pyrazolyl end of the pyridyl-pyrazole ligand, giving rise to dimetallic corners. Subsequently, the dimetallic corner building blocks featuring two pyridine donors are coordinated by monometallic [M(bpy)(NO(3))(2)] moieties (M = Pd(II) or Pt(II)) to form homo- or hetero-metallomacrocycles.

The Pd(TFA)2-catalyzed [4+1] annulation of chained or cyclic α-alkenyl-dicarbonyl compounds and unprotected primary amines for “one-pot” synthesis of pyrroles is reported here. Enamination and amino-alkene were involved in this practical and efficient tandem reaction. The annulation products were isolated in moderate to excellent yields with O2 as the terminal oxidant under mild conditions. In ...

The protecting-group-free asymmetric synthesis of 1,2,4-trideoxy-1,4-imino-L-xylitol is readily achieved in five steps from 2-deoxy-D-ribose and with an overall yield of 48%. Key in this synthesis is the application of our recently developed Vasella-reductive amination and carbamate annulation methodologies to the synthesis of 2-deoxy-aza-sugars. The carbamate annulation occurred with excellent...

A series of benzo-annulated rutaecarpines were prepared from anthranilic acid and 3-aminonaphthalene-2-carboxylic acid by Fischer indole synthesis as key reaction. Cytotoxicity was somewhat increased by the introduction of benzo-annulation, which was not directly related to the inhibitory activity against topoisomerases (topo) I and II. Benzo-annulation on ring A led to significant increase of ...

A sequential Diels-Alder reaction/silicon-directed [4 + 2]-annulation was developed to assemble hydroisochromene-type ring systems from menadione 2. In the first step, a Diels-Alder of the 1-silyl-substituted butadiene 1 with 2 furnished an intermediate cyclic allylsilane. Subsequently, TMSOTf promoted a [4 + 2]-annulation through trapping of an oxonium, generated by condensation between an ald...

The annulation reaction between various indoles and 2-alkoxycyclopropanoate esters is reported. Both high efficiency and complete stereochemical control were observed in some cases with this annulation process. A single stereocenter on the cyclopropane controls the diastereoselective formation of up to four new stereocenters. A different reaction course was observed with 3-substituted indole su...

Part I: The synthesis of 2-vinylindole, the parent of 2-alkenylindoles, has been achieved in three steps (70-76% yield) based on a novel allene cyclization developed in our laboratory. 2-Alkenylindoles have found use as precursors to indole and carbazole alkaloids via the Diels-Alder reaction. The key step of the synthesis involves isomerization of an arylacetylenecarbamate to an arylallenecarb...

x_~xxxx_ A total synthesis of B-cuparenone, which highlights the advantages and disadvantages of the three-carbon annulation process, is described. The cyclopentane ring system is found in numerous naturally occurring products, including such diverse compounds as steroids, prostaglandins, and terpenes. We have recently published a new method for the formation of cyclopentanones from olefins, a ...