Hakjune Rhee

Hexanuclear manganese metallamacrocycles with tripled hydrophobic tails

A series of hexanuclear manganese(III) metallamacrocycles were synthesized using N-acylsalicylhydrazides (H3xshz) (where H3xshzH3ashz, N-acetylsalicylhydrazide; H3pshz, N-propionylsalicylhydrazide; H3hshz, N-hexanoylsalicylhydrazide; H3lshz, N-lauroylsalicylhydrazide), where the pentadentate ligands bridged the metal ions. The triple deprotonated N-acylsalicylhydrazidate (xshz 3 ) could bridge the metal ions by using a hydrazide NN group and form the hexanuclear manganese metallamacrocycle with a hole in the center. Depending on the ligands used, the tripled hydrophobic tails of different lengths are attached at both chiral faces of the metallamacrocycles. In the complex [Mn6(ashz)6(DMF)6 ]( 2), both sides of the hole are closed by the three methyl groups of the ligands. In the complex [Mn6(pshz)6(DMF)6 ]( 3a), one ethyl side chain of the ligands is located inside the hole. In complexes [Mn6(hshz)6(DMF)6 ]( 4) and [Mn6(lshz)6(MeOH)6 ]( 5), three alternating long alkyl side chains aligned at an approximately right angle to the plane of the metallamacrocycle in one direction, while the other three alkyl side chains aligned in the opposite direction. The stability of the metallamacrocycles in the solution was addressed using 1 H NMR spectroscopy. Three phenyl protons of the bridging ligands in the metallamacrocycles were observed in the upfield region.

Formal synthesis of teleocidin a via indole-Cr(CO)3 complexes

Abstract The addition of a cyano-stabilized anion to a 4-aminoindole-Cr(CO) 3 complex can be directed to selective C-7 substitution, and the resulting intermediate is part of a formal total synthesis of teleocidin A1/A2.

Oxidation of aldimines to amides by m-CPBA and BF3.OEt2

Abstract Several amides were obtained in high yields by an efficient method from the corresponding imines which are readily prepared from aldehydes. This procedure involves the oxidation of aldimines with m -CPBA and BF 3 ·OEt 2 . In this reaction, the product is strongly influenced by the electron releasing capacity of the aromatic substituent.

Homocoupling of Aryl Iodides and Bromides Using a Palladium/Indium Bimetallic System

Abstract Homocoupling of aryl iodides and bromides using catalytic amounts of palladium and stoichiometric amounts of indium proceeded smoothly to afford the corresponding biaryls in good to high yields.

New efficient method for the synthesis of the antiviral agent carbovir

Abstract An efficient synthesis of (±)-carbovir 1 and simple des(hydroxymethyl) analogues, e.g., 5 , is reported which uses a new approach for attaching nucleoside bases to cycloalkene systems.

Efficient Synthesis of Carbocyclic Nucleoside, (±)-Homocarbovir Via π-Allylpalladium Complex Formation from the Allyl N,N-Ditosylimide Substrate

Abstract The synthesis of a carbovir analogue, (±)-homocarbovir (3) was achieved from norbornadiene (4) in seven steps and 27% overall yield. This route involves a Meinwald-type rearrangement, an acid-hydrolysis of N-tosyl bicyclic enamine 5, and a Pd(0)-catalyzed coupling reaction.

Palladium-Catalyzed Benzylation of Arylboronic Acids with N,N-Ditosylbenzylamines

The palladium-catalyzed coupling of N,N-ditosylbenzylamines with arylboronic acids has been investigated, and the resulting diarylmethanes were obtained in high yields. Conversion of the amine to a N,N-ditosylimide group provided an efficient leaving group for the Pd-catalyzed benzylation of arylboronic acids.

Colloidal Palladium Nanoparticles with In Situ H2: Reducing System for α,β-Unsaturated Carbonyl Compounds

Abstract A new reducing system comprising Pd(OAc)2 and NaBH4 in methanol to generate palladium nanoparticles has been efficiently utilized to reduce a variety of unsaturated carbonyl compounds. These were reduced to their corresponding saturated alcohols and fully saturated compounds in selected cases. This protocol presents alternative and mild reaction conditions for reduction.

A FACILE SYNTHESIS OF CIS-4-AMINO-2-CYCLOPENTENE-1-METHANOL, A KEY INTERMEDIATE FOR THE SYNTHESIS OF CARBOCYCLIC NUCLEOSIDES

ABSTRACT A number of carbocyclic nucleosides can be synthesized from (±)-cis-4-amino-2-cyclopentene-1-methanol (3). Carbocyclic amino alcohol 3 is a key intermediate that makes possible the efficient synthesis of the carbocyclic nucleosides. In this study we wish to report an efficient synthesis of carbocyclic amino alcohol 3 from inexpensive and readily available starting material. The synthetic route employed cyclopentadiene (4) as a starting material and proceeded in 38% overall yield through 6 steps involving a hetero Diels-Alder reaction and an aza-Claisen rearrangement.

Catalytic allylic arylation of cinnamyl carbonates over palladium nanoparticles supported on a thermoresponsive polymer in water

Poly(NIPAM-co-4-VP) undergoes a phase transition at the low critical solution temperature with a change from the hydrophilic to the hydrophobic core in a hydrophilic solvent. Palladium nanoparticles supported on such a thermoresponsive polymer support were demonstrated to catalyze the Tsuji–Trost reaction for the arylation of various cinnamyl carbonates by arylboronic acids. Therefore, a protocol developed using mild reaction conditions demonstrates the recyclability of the catalyst in an eco-friendly solvent such as water.