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By applying carbonyl compounds as sources of alkyl groups to the indium-catalyzed reductive alkylation of indoles, a reliable and practical method capable of offering a wide range of alkylindoles with structural diversity has been developed. An important feature of this method is that the loading of the indium catalyst can be reduced by more than that of the original alkyne-based system.

Key step in the synthesis of D-desosamine and analogs (V) is the chromatography-free procedure for the coupling of chiral nitrobutanols (I) with glyoxal to give pure 3-nitro sugars by crystallization.

Synthesis of aryl phosphinates was achieved through cross-coupling reactions of aryl iodides with H -phosphinates catalyzed by nickel under mild conditions. The method was applicable to various aryl iodides and H -phosphinates having defined stereochemistry at the phosphorus atom.

The synthesis of isoindolinones via copper-catalyzed sp3 C–H functionalization of 2-alkyl-N-substituted benzamides is described. This process does not require the preparation of halogenated substitutes, expensive transition metals, or toxic Sn or CO gas. This method provides an efficient approach to generate various functionalized isoindolinones.

The stereochemistry of inuloidin (1), which was a sesquiterpenoid that was characterized as a plant growth inhibitory substance from Heterotheca inuloides, was investigated. The modified Mosher's method coupled with a total synthetic study using osmium oxidation and Burgess dehydration as key steps were performed to clarify the stereochemistry of 1, which was determined to be a 2S,4R isomer.

This method was successfully applied in the synthesis of compound (XV), an important segment of atazanavir.

The total synthesis of the proposed structures (Ia) and (IIa) of Incargutines A and B reveals significant differences in their spectral properties compared to the natural products.

We examined In(OTf)3-catalyzed enolization and intramolecular Alder-Rickert reactions of cyclohexenone derivatives. The 3-aryl substituted cyclohexenone derivatives bearing an ethoxycarbonyl-substituted alkyne moiety could be converted into the corresponding phenols in comparatively good yield.

The α-fluorovinyl diphenyl sulfonium salt 1 is attractive due to its high potential for the synthesis of mono-fluorinated cyclopropanes and aziridines as useful three-membered rings. The synthetically useful salt 1 is readily prepared from α-fluorovinyl phenyl sulfide and diphenyl iodonium salt in one step.

The ring-opening reaction of 2-trifluoromethyl-N-tosylaziridine with a variety of heteroatom- and carbon-centered nucleophiles is achieved under basic conditions in good to high yields with excellent regioselectivity.

This highly efficient reaction for the allylation of a variety of carbonyl derivatives is the first synthetic method using catalytic amounts of a zinc amide.

The Pictet-Spengler reaction is performed as a one-pot procedure by condensing thienylethylamine (I) with carbonyl compounds (II), followed by treatment of the in situ formed imines with acetic-formic anhydride (III) to produce a formyliminium ion, which upon treatment with TFA cyclizes into tetrahydrothienopyridines (IV).

Lipid-bound macrocycles, prepared by dispersing an aqueous solution of lipophilic polyamine ligand and a vesicle-forming lipid, showed specific binding abilities for transition metal cations., the resulting complex being instantly precipitated by addition of perchlorate anion and easily recovered, as for insoluble immobilized systems.

The enantioselective hydrophosphonylation of aromatic aldehydes with silylphosphite ( 1 ) or diethyl phosphonate ( 5a ) assisted by chiral titanium alkoxides as catalyst is examined. Titanium alkoxide ( 7 ), derived from L -tratrate and Ti(O-iPr) 4 , was found to be an effective catalyst and induce modest enantioselectivity in the reaction.

The reaction of cyclopentadienyl anions with Fe(CO)5 in the presence of acyl chlorides or carboxylic anhydrides gave cyclic acyliron complexes [η5-C5H4C(OCOR)=C(OCOR)CO]Fe(CO)2 via triple carbonylation of the anions and a double acylation. The structure of [η5-C5H4C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)2 thus obtained was confirmed by the X-ray analysis. Diastereomers of indenyl derivative [η5-C9H6C(OCOCH2CH3)=C(OCOCH2CH3)CO]Fe(CO)(P(OCH3)3) were prepared by substitution of CO ligand with trimethyl phosphite and the structure of the diastereomers were characterized by NMR spectroscopy using 2D technique. Treatment of cycloheptatrienyl anion with Fe(CO)5 and acyl chloride resulted in double carbonylation to give [η5-C7H6C(OCOR)=C(OCOR)]Fe(CO)2. The mechanism of the reaction is proposed.

Photolysis of 9α-azido-3β,20β-diacetoxy-5α-pregnan-11-one in methanol gave the N-acyl imine 11-aza-3β,20β-diacetoxy-C-homo-5α-pregn-9,11-en-12-one 4 and the aminoketone 9a-aza-3β,20β-diacetoxy-9-me...

Aroylketene (2) generated by pyrolytic decarbonylation of 5-aryl-2,3-dihydro-2,3-furandione (1) reacted with 1-aryl-1-trimethylsilyloxyethylene (3) in a regioselective manner to give 2,6-diaryl-4H-pyran-4-one (5) and/or 1,5-diarylpentane-1,3,5-trione (6). This reaction provides a simple synthetic method of 2,6-diaryl-4H-pyran-4-one with various substituents in the aryl group

It is thought that metal cluster compounds hold great potential as catalysts for the multiple-electron reduction of small molecules, since they contain several metal atoms in close proximity, available for multiside bonding. However, very few examples of catalysis by metal clusters have been documented so far. In the course of the electrochemical investigation of Nb(5+) in H{sub 2}SO{sub 4} and the mechanism for the formation of the trinuclear cluster anion [Nb{sub 3}O{sub 2}(SO{sub 4}){sub 6}(H{sub 2}O){sub 3}]{sup 5{minus}}, the authors found that the niobium cluster electrocatalyzes the reduction of 12 M H{sub 2}SO{sub 4} to H{sub 2}S on a Hg electrode at room temperature at -1.2 V vs Hg/Hg{sub 2}SO{sub 4} (-0.6 V vs NHE). The reduction of sulfate to sulfide is an important step in the sulfur biological cycle. In plants and some bacteria, the reduction is achieved through several intermediate steps, each requiring a different enzyme. Concentrated H{sub 2}SO{sub 4} can be reduced by a variety of metals at elevated temperatures (>230 {degrees}C) to H{sub 2} and SO{sub 2}. With Zn and Cd, some H{sub 2}S and elemental S depending upon the I{sup {minus}}/I{sub 2} concentrations. This latter reaction, however, required solid KI and was not established tomore » be catalytic.« less

The photoreaction of 2,3-di[(E)-styryl]pyrazine derivatives was carried out in the crystalline state and in solution. Among them, 2,3-di(p-chlorostyryl)pyrazine and 2,3-di(p-cyanostyryl)pyrazine were photoreactive in the crystalline state and gave, upon photoirradiation, [2.2]orthocyclophanes in 76 and 58% yields, respectively. Such a topochemical photo-behavior was interpreted on the basis of X-ray crystallographic analyses of the crystals. The photoirradiation of 2,3-distyrylpyrazine in solution gave [2.2]orthocyclophane and anti head-to-tail type monocyclic dimer as the major products. The yields of the products varied depending on the solvent; with decreasing the polarity of the solvent, the yield of the cyclophane decreased, whereas the yield of the monocyclic dimer increased. In a similar manner, the photoirradiation of the other 2,3-distyrylpyrazine derivatives in acetonitrile/chloroform (10/1) or acetonitrile gave the corresponding [2.2]orthocyclophanes and monocyclic dimers, respectively, as majo...

The previous paper reported on the synthesis and pharmacological evaluation of N-(6-amino-3-pyridyl)-N'-bicycloalkyl-N"-cyanoguanidine derivatives, from among which three compounds were selected as potent potassium-channel openers. In the present study, selected compounds were tested for antagonism of potassium-induced contraction of rat aorta, hypotensive activity in normotensive rats, and diuretic activity in spontaneously hypertensive rats. This led to further evaluation of compound (+/-)-10 and selection of (+)-N-(6-amino-3-pyridyl)-N'- [(1S,2R,4R)-bicyclo- [2.2.1]hept-2-yl]-N"-cyanoguanidine ((+)-10) (AL0670) for development as an antihypertensive agent. Although AL0670 is regarded as a pinacidil-type K(+)-channel opener, it showed different pharmacological and conformational profiles from pinacidil.

An excellent method of preparation of N-aryl-enamino esters (4) was achieved by developing N-N exchange reaction of an N-methyl-enamino ester (6) with di- and trimethoxyanilines (3). Thermolysis of 4 in xylene gave di- and trimethoxy-4-quinolones (7) in excellent yields

The asymmetric dihydroxylation (AD) reaction of vinylphosphonates with AD-mix-α and -β reagents was successfully applied to the enantioselective synthesis of threo - α , β-dihydroxyphosphonates. β-Aryl substituents on the vinyl phosphonates were found to be good directors for the reaction with respect to the yield and enantioselectivity. The utility of chiral α, β-dihydroxyphosphonate 2c was illustrated by the stereocontrolled synthesis of (4 S ,5 S )-4-diethylphosphono-2,2-dimethyl-5-hydroxymethyl-1,3-dioxolane 6 , a potentially useful chiron for asymmetric synthesis of α-heteroatom-substituted phosphonates.

The absolute stereochemistry of cubenene and epicubenol from cultured cells of Heteroscyphus planus was determined as both (+)-isomers by 1H and 13C NMR spectroscopy, GLC using a chiral capillary column, and optical rotations. Incubation of two geometrical isomers of deuteriated farnesyl diphosphate (FPP) with a cell-free extract from cultured cells indicated that both compounds were specifically formed from (2E,6E)-FPP. Gas–liquid chromatography–mass spectrometry (GLC–MS) and 2H NMR analyses of (+)-cubenene and (+)-epicubenol generated from [1,1-2H2]- and [6-2H]-FPP confirmed the presence of 1,2- and 1,3-hydride shifts in their formation.

A Nenitzescu reaction has been used to prepare the indole skeleton 6 having all the functional groups necessary for its conversion into 10a, a key intermediate in a short synthesis of the indolequinone EO 9.