Deuterium-Labeling Studies on the C–H/Olefin Coupling of Aromatic Ketones Catalyzed by Fe(PMe3)4

Deuterium-labeling experiments were performed for the Fe(PMe3)4-catalyzed C–H/olefin coupling using a deuterium-labeled aromatic ketone with various alkenes. While the reactions with a variety of alkenes provided the linear alkylation products formed via 1,2-insertion of alkene into an Fe–H bond, the reversible 2,1-insertion proceeded during the reaction highly depends on the choice of the alkene. No H/D scrambling resulting from 2,1-insertion/β-elimination was detected for the reactions with a vinylsilane and N-vinylcarbazole, but the reactions­ with styrenes are considered to involve rapid 2,1-insertion/ β-elimination processes to cause significant levels of H/D scrambling.

A Facile One-pot Synthesis of Substituted Quinolines via Cascade Friedlander Reaction from Isoxazoles with Ammonium Formate-Pd/C and Ketones

The Friedlander reaction is the most commonly used method to synthesis substituted quinolines, the essential intermediates in the medicine industry. A facile one-pot approach for synthesizing substituted quinolines by the reaction of isoxazoles, ammonium formate-Pd/C, concentrated sulfuric acid, methanol and ketones using Friedlander reaction conditions is reported. Procedures for the synthesis of quinoline derivatives were optimized, and the yield was up to 90.4%. The yield of aromatic ketones bearing electron-withdrawing groups was better than the ones with electron-donating substituents. The structures of eight substituted quinolines were characterized by MS, IR, H-NMR and 13CNMR, which were in agreement with the expected structures. The mechanism for the conversion was proposed, which involved the Pd/C catalytic hydrogen transfer reduction of unsaturated five-membered ring of isoxazole to produce ortho-amino aromatic ketones. Then the nucleophilic addition of with carbonyl of the ketones generated Schiff base in situ, which underwent an intermolecular aldol reaction followed by the elimination of H2O to give production of substituted quinolines. This new strategy can be readily applied for the construction of quinolines utilizing a diverse range of ketones and avoids the post-reaction separation of the o-amino aromatic ketone compounds. The conventionally used o-amino aromatic ketone compounds in Friedlander reaction to prepare substituted quinoline are laborious to synthesize and are apt to self-polymerize. While oxazole adopted in this work can be prepared at ease by the condensation of benzoacetonitrile and nitrobenzene derivatives under the catalysis of a strong base. Moreover, the key features of this protocol are readily available starting materials, excellent functional group tolerance, mild reaction conditions, operational simplicity, and feasibility for scaling up.

Compositional Comparison of Essential Oils Extracted from Flowers and Aerial Parts of Elsholtzia winitiana var. dongvanensis Phuong Harvested in Ha Giang Province, Vietnam

Elsholtzia winitiana var. dongvanensis Phuong is a plant contains an essential oil characterized by an important chemical transformation. Essential oils were isolated from Elsholtzia winitiana var. dongvanensis Phuong flowers and aerial parts by hydrodistillation and analyzed for chemical constituents by GC-MS. Twenty-two components accounting for 99.99% of the total oil of flowers and twenty-three components accounting for 98.72 % of the total oil of aerial parts were identified. The composition of the essential oil contains aldehyde, aromatic ketone, monoterpenoid and secquiterpenoid. Major components found in two essential oil samples were andehyde, terpenoid, ketone benzaldehyde, germacrene D, E-caryphyllene and caryophyllene oxide. Moreover, essential oil sample isolated from flowers and aerial parts of E. winitiana var. dongvannensis was dominated by the high content of rosefuran (75.67%) and rosefuran epoxide (71.33%), respectively.

Metal-Free Air Oxidation in a Convenient Cascade Approach for the Access to Isoquinoline-1,3,4(2H)-triones

Herein we describe a very useful application of the readily available trifunctional aromatic ketone methyl-2-(2-bromoacetyl)benzoate in reactions with primary amines. An unexpected in situ air oxidation that follows a cascade process allowed the access to a series of isoquinoline-1,3,4(2H)-triones, a class of heterocyclic compounds of great interest containing an oxygen-rich heterocyclic scaffold. A modification of the original protocol, utilizing a Staudinger reaction in the presence of trimethylphosphine, was necessary for the synthesis of Caspase inhibitor trione with free NH group.

A review on recent advances and potential pharmacological activities of versatile chalchone molecule

Chalchone is an aromatic ketone and precursors of open chain flavonoids and isoflavonoids present in edible plants and their derivatives have attracted attention due to many potential pharmacological activities. Chalchone are also known as benzalacetophenone and phenyl styryl ketone. Modifications in their structure have offered diverse pharmacological activities that have proven useful for the development of new medicinal agents having improved potency and lesser toxicity. They are also the intermediates in the Auwer's synthesis of flavanoids and in the biosynthesis of flavanoids. Chalchone can be synthesized by various method but the two main methods are Aldol condensation method and Claisen Schmidt method. This review provides an overview of the pharmacological activities of natural and synthetic chalchone derivatives.

Photochemical reactivity of phenyl (methyl-tetrazolyl) ketone – hydrogen atom transfer vs. electron transfer

A novel photochemical electron transfer step is observed when a heteroaromatic substituent is present in an aromatic ketone.