A convenient One-Pot Synthesis of an Unsymmetrical Propane-1,3-diamine BRL 61010A

The one-pot condensation of N-methylhomoveratrylamine with acrolein followed by in situ reductive amination with 3,4-dimethoxyaniline to give an unsymmetrical propane 1,3-diamine in excellent yield is described.     

Synthesis of alkyl-H-phosphinic acid alkyl esters from red phosphorus and alkyl bromides

Alkyl-H-phosphinic acid alkyl esters are synthesized in 65–71% yield via chemoselective reaction of alkyl bromides with available alkyl-H-phosphinic acids (60–65 °C, Et3N). The latter are prepared, in turn, by direct phosphorylation of alkyl bromides with red phosphorus under phase-transfer conditions.     

Alkylation of Allyl/Alkenyl Sulfones by Deoxygenation of Alkoxyl Radicals

A challenging deoxygenation of alkoxyl radicals from readily accessible alcohol derivatives was developed, affording facile synthesis of functionalized alkenes with good functional group tolerance under mild reaction conditions. Because alkoxyl radicals can easily undergo β-fragmentations or hydrogen abstractions, this new strategy for deoxygenation of alkoxyl radicals is highly valuable. Moreover, mechanistic studies revealed that the electron-neutral phosphine acts as the deoxygenation reagent.     

Use of allylzinc halide as a source of halide: Differential addition of nucleophiles to Ts-aziridines and aldehydes under similar reaction conditions

We have observed that the allylic zinc halide under identical reaction conditions acts in different modes for different electrophiles. For Ts-aziridines the halide part of the allylic halide has been introduced as a nucleophile and for the carbonyl compounds the simple allylation reaction occurs. To the best of our knowledge this is the first report where the allylic zinc halide is the source of halide acting as nucleophile. The main advantages of the present procedure are easy to handle, no need of inert atmosphere, mild reaction conditions, and applicability to a wide variety of substrates for aziridines and carbonyl compounds.     

Unveiling the relevance of the redox character of nitroaromatic and nitroheteroaromatic compounds as potential medicines

This review discusses the state of the art, challenges, and perspectives in recent applications of nitroaromatics and nitroheteroaromatics, which are redox-bio-activated drugs or leads, in Medicinal Chemistry. It deals mainly with the electrochemical approach toward the electron transfer-based molecular mechanisms of drug action, drug design, estimation and measurement of redox potentials, correlation of physicochemical and pharmacological data, and electrochemical studies of the main representatives of nitro-containing prodrugs, along with approaches to combat their toxicity issues, aiming at a better therapeutic profile. Electrochemical investigation plays essential roles, being strategic in the design and discovery of potential medicines.     

The catalytic performance study of polymerized ionic liquid synthesized in different conditions on alkylation of o‐Xylene with styrene

In this work, a series of novel acidic polymerized ionic liquids were used as heterogeneous catalyst for alkylation of o‐Xylene with styrene. And the effect of the amount of initiator and the type of acid used for ion exchange on catalyst structure and the catalytic performance of catalysts for alkylation were studied thoroughly. The experiment results show: when the percentage of the amount of initiator in the total material is 3%, the polymerized ionic liquid catalyst MPM‐SO₃H‐[C₃V][SO₃CF₃] has the most uniform with a specific surface area of 97.30 m²/g and a pore volume of 0.35 cm³/g. Benefiting from the unique structure features, MPM‐SO₃H‐[C₃V][SO₃CF₃] manifested an excellent catalytic performance for alkylation of o‐Xylene with styrene, along with the conversion of styrene was 96.8% and the yield of 1‐Phenyl‐1‐ortho‐xylene ethane was 94.7%. Therefore, this work provides a novel reference to the synthesis of polymerized ionic liquids and clearly explains the advantage of novel acidic polymerized ionic liquids on alkylation.     

Macrocyclic Polyethers as Enolate Activators in Homogeneous and Heterogeneous Systems

Abstract

The ability of macrocyclic polyethers to activate enolates has been studied in the alkylation of de-oxybenzoin (1) with butyl derivatives nBuY (Y = Br, I, OMes) catalyzed by crown ether PHDB18C6 (7) or cryptand [2.2.2,C10] (8) under phase-transfer catalysis (PTC) and homogeneous (chlorobenzene) conditions. The enolate reactivity is mainly determined by the ligand (cryptand > crown ether) and solvent (increasing with the polarity, in the order: toluene < chlorobenzene < 1,2dichlorobenzene). Regioselectivity of the reaction is also remarkably affected by ligand and alkylating agent.     

NEW SYNTHETIC ROUTE TO DIALKYLPHOSPHINIC ACIDS

Abstract

The dialkylphosphinic acids, 5a-5e, can be obtained by reacting bis(trimethylsiloxy)phosphine with the highly reactive alkyl halides, 2a-2e, in the presence of chlorotrimethylsilane and triethylamine, followed by ethanolysis of the resulting trimethylsilyl dialkylphosphinates, 4a-4e.     

SELECTIVE ALKYLATION/ACYLATION OF DI- OR TRIANIONS: EXPEDITIOUS DERIVATIZATION OF ENDOTHELIN ANTAGONISTS[1]

ABSTRACT

Sitaxsentan sodium (1, TBC11251Na) is an ET_A selective endothelin antagonist under clinical development for pulmonary arterial hypertension and congestive heart failure. Second generation compounds, as exemplified by TBC2576 (2) are currently under development in our laboratories. To rapidly access analogs of 1 and 2, a route was developed for the selective alkylation or acylation of the corresponding di- or trianions derived from these two highly functionalized compounds. We report here on this straightforward, yet effective, procedure consisting of treating the di- or trianions with an excess amount of electrophiles, followed by a rapid quench. In this manner, selective alkylation or acylation of 1 and 2 was achieved with satisfactory yields.     

Total synthesis of attenols A and B

A concise approach for the total synthesis of attenols A and B is described involving MacMillan’s α-aminooxylation, Evan’s asymmetric alkylation, Brown’s allylation, and spiro-ketalization as key steps. This approach has successfully demonstrated the α-aminooxylation protocol for the construction of the anti-1,3-diol unit.