Rate Study of Proton Catalyzed SmI2 Reduction of 2‐Heptanone and 1,2‐Epoxydecane

Rate constants directly measured from the GC‐analyzed method for SmI₂ reduction of 2‐heptanone and 1,2‐epoxydecane in the presence of various proton sources were obtained. Water exhibits much stronger catalytic effect than methanol and t‐butanol. Dependence of reaction rates on concentration of SmI₂ and temperature were studied.     

Synthesis of Functionalized 2,3-Dihydropyrroles Promoted by Samarium Diiodide

Abstract

The intermolecular reductive coupling of 1,1-diaryl-2,2-dicyanoethylenes or 1,1-diaryl-2-cyano-2-ethoxycarbonylethylenes with substituted benzalazines induced by samarium diiodide was studied. Functionalized 2,3-dihydropyrroles were prepared in good yields under neutral and mild conditions.     

Synthesis of Substituted 4‐Aroyl‐1‐indanone and 5‐Aroyl‐1‐tetralone

Several substituted 4‐aroyl‐1‐indanones 2 and 5‐aroyl‐1‐tetralones 3 were prepared in good yields from 1‐indanones 1 via a series of reasonable transformations.     

Synthesis of Functionalized Tetrahydro‐4‐oxoindeno[1,2‐b]pyrroles from Ninhydrin,Acetylenedicarboxylates, and Primary Amines

A one‐pot synthesis of dialkyl 1,3a,4,8b‐tetrahydro‐3a,8b‐dihydroxy‐1‐alkyl‐4‐oxoindeno[1,2‐b]pyrrole‐2,3‐dicarboxylates via three‐component reaction from indan‐1,2,3‐trione hydrate (ninhydrin), primary amines, and dialkyl acetylenedicarboxylates is described.     

A Convenient Reduction-Oxidation Procedure for the Selective Epimerization at Sulfur of Highly Functionalized,Optically Active Sulfoxides

A convenient method is described for the selective epimerizatin at sulfur of highly functionalized, optically active sulfoxides. The approach followed involves a sulfoxide reduction (with 2-phenylene phosphochloridite) - oxidation (with m-chloroperoxybenzoic acid) - separation of diastereomers sequence of steps. It was applied for the conversion of 3a, 3b and 3c into 2a, 2b and 2C, respectively, key intermediates in the total synthesis of the antitumor antibiotic sparsomycin and derivatives. Overall yields range from 26% to 37%.     

Diastereoselective Synthesis of Functionalized δ‐Lactones

Abstract

An efficient and diastereoselective synthesis of functionalized δ‐lactones, based on silyl‐cupration of dimethyl‐2‐alkylidene glutarates, is described. Unmasking of the silicon group and lactonization afford the title compounds with good to excellent diastereocontrol depending on the size of the R substituent on the glutarate.     

Synthesis,molecular, and morphological characterization of initial and modified diblock copolymers with organic acid chloride derivatives

Six well defined PS‐b‐PB_1,2 diblock copolymers (PS: polystyrene and PB: polybutadiene) with almost 100% of 1,2 microstructure for the PB segment were synthesized. Size exclusion chromatography (SEC), membrane osmometry (MO) and proton nuclear magnetic resonance spectroscopy (¹H NMR) were used for verification of the molecular characteristics and the 100% ‐1,2 addition for the PB blocks. Modification with heptanoyl or pentadecafluorooctanoyl chloride was accomplished via hydroboration and subsequent oxidation, leading to hydroxylated PB blocks and was verified with ¹H NMR and Fourier transform infrared (FTIR) spectroscopy. Only two samples were modified with both organic acid chloride derivatives. Structural characterization was accomplished via transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) in all cases. The self‐assembly was more evident in the modified copolymers with the corresponding halides due to the increase of the molecular weight of the modified PB block. Taking into consideration the χN values in each case and comparing the results with those of PS‐b‐PI copolymers already reported in the literature the discrepancies with the theoretical predictions are very small or minimal. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A New Approach to the Synthesis of Dithienylethanediones and Dithienylacetylenes

1,2-Dithienylethanediones were synthesized by modified acylation of thiophene and its homologs in the presence of aluminum chloride and pyridine. The bishydrazones of the products were converted into dithienylacetylenes by oxidation with atmospheric oxygen in pyridine in the presence of CuCl.     

Stereo- and regiospecific four-molecule reaction of aroyl chlorides with iso-pentylene: direct formation of (E)-β,γ-unsaturated carbonyl compounds promoted by samarium metal in DMF

Promoted by samarium metal in DMF, aroyl chlorides react readily with iso-pentylene in a four-molecule manner, which offers an efficient stereo- and regiospecific synthesis of (E)-β,γ-unsaturated carbonyl compounds and also provides a facile method for the construction of monoterpene skeleton. The reaction is an additional example of organic reactions mediated by direct use of unactivated metallic samarium.     

Gold(I)‐Catalyzed Furan‐yne Cyclizations Involving 1,2‐Rearrangement: Efficient Synthesis of Functionalized 1‐Naphthols and Its Application to the Synthesis of Wailupemycin G

Gold‐catalyzed cascade cyclization/1,2‐rearrangement of 1‐(2‐furanyl)phenyl propargyl alcohols has been developed, which provides a rapid and efficient access to multisubstituted 1‐naphthols bearing an enal or enone moiety with high stereoselectivity. The (Z)‐ or (E)‐stereochemistry can be easily controlled by choosing protected‐ or non‐protected substrates. The utility of the methodology has been illustrated in the first total synthesis of wailupemycin G.     

Stereoselective Synthesis of Functionalized 1,3-Dienes in Water

An efficient synthesis of functionalized 1,3‐dienes via one‐pot reactions between dialkyl acetylenedicarboxylates?, 1,3‐dicarbonyl compounds and secondary amines in ?water as the solvent is described. The mild reaction condition high yields and the ?new products are advantages of our method.     

A Novel Synthesis of Vinyl Dithiocarbamates via Phosphonium Ylides

In the presence of potassium carbonate, N, N-dimethylamino thio-carbonyl thiomethyl triphenylphosphonium bromide can form the corresponding ylide in situ, which can undergo Wittig reaction with aldehydes to give vinyl dithiocarbamates in high yields. If the esters were hydrolysized in the presence of mercuric chloride, a new method to lengthen aldehydes by one carbon atom was accomplished.     

Practical Synthesis of Functionalized 2‐Thioxoimidazolidine Derivatives

High‐yielding syntheses of an unpublished series of 2‐thioxo‐imidazolidin‐4‐ones 6 bearing an N‐ethoxycarbonyl and amidyl moieties an N₁ and C₅, respectively, are reported. These derivatives were obtained by intramolecular cyclization of 3‐ethylhydrazinoacetate 3,4‐dihydro maleimides 4 in the presence of ethyl or phenylisothiocyanate 2 under neutral conditions.     

Samarium reagent-promoted formation of benzoins from diarylmethanones and DMF via a carbene rearrangement reaction

Prompted by samarium metal in DMF with TMSCl or iodine as an activator, or by SmI₂/THF system, diarylmethanones react readily with DMF to afford benzoins in moderate to good yields via rearrangement of aryl groups. As for asymmetric diarylmethanones, products resulting from the migration of either aryl group were obtained, where the migration of aryl groups shows certain priority.