Solvent-Free Conversion of N,N-Dimethylhydrazones to Nitriles Under Microwave Irradiation

A variety of aldehyde N,N-dimethylhydrazones are rapidly converted into the corresponding nitriles using oxone supported on wet Al₂O₃ under microwave irradiation in dry media.     

Study on the Regioselectivity of Rhodium-Catalyzed Ring Opening Reactions of C1-Substituted 7-Oxabenzonorbornadienes with Boronic Acids

An optimized condition for the rhodium-catalyzed ring-opening reaction of C₁-substituted oxabicyclic alkenes with aryl boronic acids was developed and the effect of aryl boronic acid as well as the effect of C₁ substitution on the oxabicyclic alkenes was studied. Aryl boronic acids carrying electron-donating substituents provided the ring-opened products in excellent yields regardless of the position, while electron-withdrawing substituents were more susceptible to steric interactions. Although two different regioisomers are possible, all the rhodium-catalyzed ring-opening reactions of C₁ substituted oxabicyclic alkenes studied with aryl boronic acids were found to be highly regioselective, giving single regioisomers in all cases.     

CeCl3·7H2O-Catalyzed Synthesis of 1-Oxo-hexahydroxanthene Derivatives in Aqueous Media

Cerium(III) chloride heptahydrate (CeCl₃·7H₂O) catalyzes the reaction of substituted salicylaldehydes with 1,3-cyclohexane dione or dimedone in aqueous medium at reflux temperature to afford the corresponding 1-oxo-1,2,3,4,9,10-hexahydroxanthene derivatives4 0 in high yields.     

Synthesis of Alkyl and Aryl Substituted Benzo[h]Naphtho[1,2-b][1,6]naphthyridines

The reaction of 4-chloro-2-methylquinolines and 1-naphthylamine under neat conditions yielded 2-methyl-N-(1-naphthyl)quinolin-4-amines. These potential intermediates on reaction with aliphatic and aromatic carboxylic acids yielded the respective 7-alkyl and -aryl substituted benzo[h]naphtho[1,2-b][1,6]naphthyridines. The highly deshielded protons in the final compounds were assigned on the basis of 2D NMR studies.     

Cerium(III)-Catalyzed Synthesis of Schiff Bases: A Green Approach

The reaction of primary aromatic amines with aryl aldehydes is found to be catalyzed by cerium chloride heptahydrate under solvent-free conditions to give the corresponding Schiff bases in good yields.     

Chemoselective Reduction and Transesterification of α-Keto Propargylic Esters Mediated by NaBH4 and CeCl3 · 7H2O

An efficient one-pot synthesis of α -hydroxy propargylic esters by chemoselective reduction followed by transesterification using NaBH₄ in combination with CeCl₃ · 7H₂O is described.

Synthesis of Metal‐Free Phthalocyanines in Functionalized Ammonium Ionic Liquids

A convenient, fast, efficient, and ecofriendly synthesis of metal‐free phthalocyanines from various substituted phthalonitriles in different hydroxyalkylammonium ionic liquids in the presence of 1,8‐diazabicyclo‐[5,4,0]‐undec‐7‐ene (DBU) is reported in moderate yields. The effect of concentration of DBU and temperature on the synthesis of phthalocyanine in N‐(2‐hydroxyethyl)‐N,N‐dimethylbutylammonium bromide ionic liquid has been examined, and the ionic liquid has been recovered and reused conveniently.     

Oxidative Addition of 4-Hydroxycoumarin to Alkenes. An Expeditious Entry to 2,3-Dihydro-4H-furo-[3,2-c][1]benzopyran-4-ones1

In the presence of one-electron metal oxidants (CAN, MAH), 4-hydroxycoumarin (1) adds to alkenes to give 2,3-dihydro-4H-furo[3,2-c][1]benzopyran-4-ones.     

Synthesis of 7‐Alkoxy/Hydroxy‐α‐methyltryptamines

Abstract

A simple method for the preparation of 7‐alkoxy/hydroxy‐α‐methyl‐DL‐tryptamines is reported. The key steps of the synthesis are the Japp–Klingemann coupling of 2‐piperidone‐3‐carboxylic acid 3 with diazonium salts 4, the Fischer‐type cyclization of hydrazones 5 to β‐carboline derivatives 6 and their hydrolysis to title compounds 8.     

Improved synthesis of (R)-7-hydroxycarvone from (S)-α-pinene

A three-step synthesis of (R)-7-hydroxycarvone (1), which is anticipated to be a valuable building block for the versatile preparation of natural products, is described. Optimization of the reaction conditions for photooxygenation and migration of (S)-α-pinene 2, tetrapropylammonium perruthenate (TPAP) oxidation of the generated alcohol, and a subsequent ring-opening reaction in the presence of Cu(OTf)₂ led to the synthesis of 1 with good reproducibility. The desired product 1 was thus obtained in 46% yield over three steps.