Ball-milling Synthesis of Tetrahydroquinolines via ‘One-pot’ Three-component Diels-Alder Reaction Catalyzed by Phosphotungstic Acid

We reported an economic and practical ball-milling method for the synthesis of tetrahydroquinoline derivatives via a ‘one-pot’ three-component Diels-Alder reaction of anilines, aldehydes and alkenes catalyzed by phosphotungstic acid at room temperature. For this reaction, a simple ‘one-pot’ ball-milling operation was conducted, readily available starting materials were employed, ‘one-pot’ conditions were applied, and the most important was to use inexpensive and environmentally friendly catalyst phosphotungstic acid. Various tetrahydroquinolines, which might be potentially applicable in the pharmaceutical and biochemical areas, were conveniently synthesized in mo-derate to excellent yields.     

One-pot Synthesis of Divalent and Trivalent Cluster Mannosides via Ugi Four-component Reaction

The Ugi four-component reaction (U-4CR) was utilized to prepare divalent and trivalent cluster mannosides. Thus, two target compounds 6 and 8 were obtained efficiently using carboxymethyl 2, 3, 4, 6-tetra-O-acety-α-D-mannopyranoside 4 as acid component, and 1, 6-hexanediamine or tris(2-aminoethyl)amine as the multivalent scaffolds.     

Facile Synthesis of Ophipogonin C＇ and its Three Analogues

Three natural diosgenyl glycosides： Ophipogonin C （A）, Polyphillin C （B）, diosgenyl α-L-rhamnopyranosyl-（1→4）-β-D-glucopyranoside （DRG） （C） and one of their analogue diosgenyl α-L-rhamnopyranosyl-（1→6）-β-D-glucopyranoside （D） were first systemic synthesized in a facile way in high yields.     

Facile Synthesis of Ophipogonin C′ and its Three Analogues

Among the huge number of glycoconjuates, the steroidal glycosides are often found as the major components in traditional Chinese medicine. Steroidal glycosides constitute a structurally and biologically diverse class of molecules which have been isolated from a wide variety of both plant and animal species 1. Because of the variety of promising pharmaceutical properties2, the large family of steroidal glycosides has received considerable attention of chemist. Figure 1 OOOOR4R3OR2OOR1O …     

Synthesis of Novel Bisoxazoline Ligands for the Enantioselective Diels-Alder Reaction

The Diels-Alder reaction is the most useful method for six-membered ring formation1. As a consequence, a number of effective enantioselective processes have been developed over the years 2-4. Of particular interest, metal bisoxazoline complexes formed fro…     

Synthesis of 2-Acyl-2H-1,2,3-diazaphospholes and Their Diels-Alder Reaction with Cyclopentadiene

2H-1,2,3-Diazaphospholes 3a-3h were prepared from various ketone acylhydrazones and phosphorus trichloride in the presence of triethylamine. Compounds 3 underwent feasible hetero-Diels-Alder reactions with cyclopentadiene to afford the respective anellated [1,2,3]diazaphospholes 4a--4d as well as 4a‘--4d‘ in moderate yields. The endo rule in the reaction was observed under kinetic control conditions.     

A Facile and Green Synthesis of Sulforaphane

Sulforaphane (1, SFN), 4-methylsulfinylbutyl isothiocyanate, was considered as the most potent inducer of phase II enzymes proteins [glutathione transferases (GSTs) and NAD(P)H: quinone reductase (QR)] selectively, and strong inhibitor of phase I enzymes …     

Samarium Triflate as Mild and Efficient Catalyst for Aza-Diels–Alder Reaction: A Facile Synthesis of cis-Fused Pyrano- and Furanoquinolines

Three-component coupling reactions of aldehydes, amines, and cyclic enol ethers have been carried out in the presence of samarium triflate to afford the corresponding pyrano and furanoquinolines in excellent yields with high endo-selectivity. The reaction conditions are mild and amenable to scale-up.     

Facile Synthesis of Isoamericanol and Isoamericanin A

A number of benzodioxane compounds were synthesized using the palladium-catalyzed etherification of aryl halides by employing triphenylphosphane ligands. This method was used as key step in the synthesis of isoamericanol A and isoamericanin A.     

Reaction of Perfluoroalkanesulfinyl Chlorides with Enamines: A Facile Synthesis of α-Perfluoroalkanesulfinyl Ketones and Aldehydes

The reaction of perfluoroalkanesulfinyl chlorides with enamines was achieved in the presence of triethylamine, and α-perfluoroalkanesulfinyl carbonyl compounds were obtained in moderate to good yields after hydrolysis of the reaction intermediates with dilute hydrochloric acid.     

A Novel Synthesis of 1-Isochromanols via Hetero Diels-Alder Reaction of Carbonyl Compounds with 1-Trimethylsilyloxy-benzocyclobutene as a Precursor of α-Oxy-o-Quinodimethane Under Mild Condition

Reaction of 1-trimethylsilyloxybenzocyclobutene(1) with carbonyl compounds catalyzed by tris(dimethylamino)sulfur (trimethylsilyl)difluoride (TASF) at room temperature gave 1-isochromanol derivatives as corresponding hetero Diels-Alder adducts in good yields.     

Facile and Efficient One-Pot Synthesis of β-Carbolines

Initial formation of tetrahydrocarboline 3 from tryptophan methyl ester 1 and aldehyde 2 by Pictet–Spengler reaction, followed by treatment with trichlorocyanuric acid, provides a facile and efficient route for a one-pot synthesis of β-carbolines with excellent yields.     

o-Benzenedisulfonimide as a Recyclable Homogeneous Organocatalyst for an Efficient and Facile Synthesis of 4-Amidotetrahydropyran Derivatives Through Prins–Ritter Reaction

A highly diastereoselective synthesis of 4-amidotetrahydropyran derivatives has been achieved using a catalytic amount of o-benzenedisulfonimide under mild conditions involving sequential allylation and Prins–Ritter amidation. The oxo-carbenium ion formed in Prins cyclization could be successfully trapped with nitriles through Ritter amidation. The catalyst is highly efficient in promoting both allylation and Prins cyclization with a net addition of nitrile. The catalyst can be easily recovered and reused in subsequent reactions.     

A Facile and Efficient Synthesis of Substituted Pyrroles by Three Component Coupling Reaction of Amines, Aldehydes and Nitroalkanes

A facile and efficient synthesis of highly substituted pyrroles has been achieved by a one-pot three-component coupling reaction of aldehyde, amine and nitroalkane by triethyl orthoformate.     

Facile and Versatile Route to the Synthesis of Fused 2‐Pyridones: Useful Intermediates for Polycyclic Sytems

The reaction of various heteroaromatic amino nitriles with diethyl malonate under basic conditions is reported. This reaction affords a series of different highly functionalized 2‐pyridone condensed systems, which can be suitable intermediates in the construction of polyheterocyclic structures.     

α-Phosphoryl Cyclopentanones as Possible Intermediates in the Total Synthesis of Sarkomycin

Abstract

In an effort to synthesize sarkomycin 1 trans-2-diphenylphosphinoyl-3-tris (methylthio) methyl-cyclopentanone 7 and trans-2-diphenylphosphinoyl-3-carbo-methoxy-cyclopentanone 8 were prepared. The Horner-Wittig reaction of the latter with formaldehyde failed. (±)-Sarkonycin 1 was prepared by a sequence of reactions starting from diethyl 2-oxopropanephosphonate. The key steps in this synthesis involve the intramolecular carbenoid cyclization of 1-diazo-2-oxopropanephosphonate 10 and the Horner-Wittig reaction of 2-diethoxyphosphoryl-3-carboxy-cyclopentanone 12 with formaldehyde.     

Energetics of C–C Bond Scission in Ethane Hydrogenolysis: A Theoretical Study of Possible Intermediates and Reaction Pathways

C–C bond scission steps, which are often considered as rate-determining in ethane hydrogenolysis, are studied by the Unity Bond Index–Quadratic Exponential UBI–QEP method. The binding energies of atomic carbon with Group VIII and IB metal surfaces Ni(111), Pd(111), Pt(111), Rh(111), Ru(001), Ir(111), Fe(110), Cu(111), and Au(111) are estimated using experimental data on the adsorption of various species on these surfaces. These estimates are corrected using data from density functional theory (DFT) on the adsorption heats of the CH _x species. Metal surfaces are arranged in the following series according to the binding strength of a carbon atom: Cu(111) < Au(111) < Pd(111) < Ru(001) Pt(111) < Ni(111) Rh(111) < Ir(111) < Fe(110). The values of chemisorption heats range from 121 kcal/mol for Au(111) to 193 kcal/mol for Fe(110). The activity of these surfaces toward C–C bond scission increases in the same series. The results of this work suggest that the most probable C–C bond scission precursors are ethyl, ethylidyne, adsorbed acetylene, CH₂CH, CH₂C, and CHC. Theoretical data obtained by different methods are compared and found to agree well with each other. An overview of experimental data on ethane hydrogenolysis mechanisms is given.     

Studies of the Total Synthesis of Epothilone B and D:A Facile Synthesis of C7-C14 and C15-C21 Fragments

A mild and highly efficient synthesis of C7-C14 and C15-C21 fragments of epothilone B and D is described in which racemic C7-C14 fragment is prepared from nerol through four steps and C15-C21 fragment is obtained from 1,3-dichloroacctone.thioacetamide and propionaldehyde.     

Efficient and Facile Synthesis of ( ± )-Salvirecognine

Salvirecognine (7) is a diterpene isolated from Salvia recognita[1] which has been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family. [2] In order to study further relationships between the structure and biological activity of the diterpene compounds and as an extension of diterpenoid synthesis in our laboratory, [3,4] the first total synthesis of the title compound was achieved by an efficient and facile route (Scheme 1).