Wacker-type oxidative functionalization of β-substituted unsaturated sulfoxides

The Wacker-type oxidation is an important procedure catalyzed by palladium complexes. A mild and general method for the preparation of β-substituted-δ-oxosulfoxides from the corresponding β-substituted-γ,δ-unsaturated sulfoxides is described. The products are versatile synthetic intermediates for the preparation of syn- and anti-1,3-diol and 1,3-aminoalcohol derivatives.     

One-pot easy conversion of Baylis-Hillman adducts into carbamates of unsaturated β-amino acids

An easy, one-pot transformation of Baylis-Hillman adducts into carbamates of unsaturated β-amino acids, for example, 2-(aryl(methoxycarbonylamino)methyl)acrylic acid methyl esters 7 and 2-(methoxycarbonyl aminomethyl)-3-arylacrylic acid methyl esters 8 via reaction with the Burgess reagent is described.     

Advanced procedure for the enzymatic ring opening of unsaturated alicyclic β-lactams

Enantiopure β-amino acids 1a–4a and β-lactams 1b–4b were prepared simultaneously through the lipolase-catalysed enantioselective ring opening of unsaturated racemic β-lactams (±)-1-(±)-4. High enantioselectivities (E>200) were observed when the reactions were performed with 1 equiv of water in iPr₂O at 70 °C. The resolved (1R,2S)-amino acids (yield⩾45%) and (1S,5R)-, (1S,6R)- and (1S,8R)-lactams (yield⩾47%) could be easily separated. The ring opening of lactam enantiomers 1b–4b with 18% HCl afforded the corresponding β-amino acid hydrochlorides 1c·HCl–4c·HCl (ee >95%).     

Enhancement of the luminescence of europium(III) β-diketonates in the ligand series β-diketones-their unsaturated analogues-copolymers

A change in the luminescence intensity of europium compounds was studied for the series of ligands β-diketones-their unsaturated analogues (monomers)-copolymers with styrene (methyl methacrylate). The optimal ratios of comonomers (1 : 2; 1 : 5) providing the maximum luminescence intensity of europium were determined. Europium (n x 10^-3%) was determined in Ce, Pr, Nd, and Ho oxides, which are strong luminescence quenchers, using copolymers containing trifluoroacetylacetone and benzoylacetone.     

Synthesis of β-silyl ketones via reaction of trimethylsilyllthium with unsaturated hydrazones. Application to the synthesis of brevicomin

Trimethylsilyllithium undergoes conjugate addition to dimethylhydrazones of α,β-unsaturated ketones. The resulting metalloenamine intermediates can be alkylated, and the resulting hydrazone products cleaved to give α-substituted-β-silyl ketones. These reactions, together with a silicon-directed Baeyer-Villiger reaction, have been applied to the synthesis of brevicomin.     

Studies in the field of derivatives of unsaturated phosphonic acids 21. Esters and amides of β-ethylhexoxyvinylphosphonic acid

Summary -(-Ethylhexoxy)-vinylphosphonic dichloride, diethyl, dipropyl, dibutyl, di-isobutyl, di-isoamyl, dihexyl, di-2-ethylhexyl, di-(methoxyethyl) and di(ethoxyethyl) esters of -(-ethylhexoxy)-vinylphosphonic acid, tetramethyldiamide, tetraethyldiamide and dipiperidide -(-ethylhexoxy)-vinylphosphonic acid were prepared and characterized.     

A new diastereoselective intramolecular electroreductive coupling of unsaturated β-ketoesters and β-ketoamides in ionic liquids at a tin cathode

The diastereoselective intramolecular electroreductive coupling of several β-ketoesters and β-ketoamides has been accomplished at a tin cathode in ionic liquids and isopropanol (9:1). The ionic liquids used are 1-butyl-3-methylimidazolium bromide [BMIM]Br, 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF₄, 1-methoxyethyl-3-methylimidazolium trifluoroacetate [MOEMIM]CF₃COO and 1-methoxyethyl-3-methylimidazolium mesylate [MOEMIM]Ms. This methodology offers a clean and green process for the synthesis of functionalized carbocycles in good yields with excellent stereochemical control at three stereogenic centres.     

Synthesis of unsaturated phosphatidyl inositol-3,4,5-trisphosphate

Phosphatidylinositol polyphosphate (PIPx) are related with tyrosine kinase activation and cell proliferation and carcinogenesis. PIPx is an important target compound for synthetic organic chemist. PIPx having saturated fatty acid components have been reported. Recently we have succeeded in the synthesis of phosphatydylinositol-3,4,5-trisphosphate with unsaturated fatty acid component by the reaction of diethyl chlorophosphite with l,2-di-O-cyclohexylidene-3,4-O-(tetraisopropyldisiloxane 1,3-diyl)-6-O-(4-oxopentanoyl)-myo-inositol.     

The effect of alkyl substitution on the conformation of intramolecularly hydrogen bonded β-γ (enolic) unsaturated alcohols

The equilibrium between associated (OH ⋯ π) and free OH conformations of β-γ unsaturated alcohols has been found to be highly dependent upon the position of alkyl substitution. Two types of intramolecularly hydrogen bonded conformations can be identified which are separated by a difference in OH stretching frequency of approximately 10 cm⁻¹. The occurence of either conformation is dependent upon methyl substitution at the β carbon and the conformations are mutually exclusive. The intensity ratio of the free and intramolecularly hydrogen bonded OH stretching bands are dependent upon the alkyl chain length and also the primary or secondary nature of the alcohol. In both cases, changes in relative intensity result from steric interactions. Increased alkyl chain length decreases the relative intensity of the intramolecularly hydrogen bonded band, whilst a change from primary to secondary alcohol increases the relative intensity of the intramolecularly hydrogen bonded band.     

Metathesis transformations of unsaturated derivatives of β-diketones

Selected β-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis with selected olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly with good yields and selectivities.      

Friedel—Crafts alkylations of ferrocene with unsaturated lactones. Some unusual reactions caused by the β-ferrocenylcarbenium ion

Friedel—Crafts alkylations of ferrocene with 5- and 6-membered unsaturated lactones have been studied. The expected alkylation products were isolated in the case of 5-membered lactones, while several products such as unsaturated ferrocenyl-lactones, ferrocenyldiketones as well as ferrocenylhydroxylactones were isolated in the case of 6-membered lactones. β-Ferrocenylcarbenium ion was suggested to be the key intermediate in this case.     

Addition of some α-halo ethers to unsaturated compounds

Summary The addition was carried out of 2-acetoxyethyl chloromethyl ether and of 2-chloroethyl chloromethyl ether to isobutene, to allyl chloride, to styrene, and to allyl acetate and also of 2-acetoxyethyl chloromethyl ether to butadiene and to ethyl cinnamate.     

Synthesis of carba-β-d- and l-idopyranosides by rearrangement of unsaturated sugars

The triisobutylaluminium- (TIBAL) and titanium(IV)-promoted conversions of 6-deoxyhex-5-enopyranosides into highly functionalised cyclohexane derivatives provide intermediates for the synthesis of enantiomerically pure carba-sugars. The preparation of enantiomerically pure methyl carba-β-d-idopyranoside 1, methyl carba-β-l-idopyranoside 2 and 5′a-carbadisaccharide 3 is reported.     

Cu(I)- and Cu(II)-catalyzed cyclo- and Michael addition reactions of unsaturated β-ketoesters

The α-alkylidene β-ketoesters 2-carbethoxycyclopentenone (1a) and ethyl 2-benzoylacrylate (1b) react with 1,2-dimethylbutadiene (2) (Diels-Alder), N-benzyl-N-(cyclohexylethynyl)-4-methylbenzenesulfonamide (3) (Ficini reaction), ethynyl(phenyl)sulfane (4) ([2 + 2] cycloaddition), and 1,2,5-trimethyl-1H-pyrrole (5) (Michael addition) in the presence of copper(I) (6) or copper(II) triflate (7) (1-2 mol %) in dichloromethane. This convenient protocol converts 1a and 1b to the corresponding cycloaddition (8-10) or Michael addition (11) products in good yields after reaction times of 0.5-3 h without requiring purified solvents or inert gas atmosphere.     

Stereochemistry in alkylations of dianions of β-hydroxysulfoxides and β-hydroxysulfones

Alkylations of dianions of β-hydroxysulfoxides and β-hydroxysulfones have been found to be affected by chelation of a Li cation with a sulfinyl group and by coordination of the cation with tetrahydrofuran rather than a sulfonyl group, respectively.     

π-Relaxation of the ring strain: design of polycyclic unsaturated silicon molecules

Introduction of a double bond into cyclic silanes lowers the ring strain by the cyclic delocalization of π-electrons through the hyperconjugation with the σ bonds, which is favored by the high π-orbital energy of the SiSi bond and the low σ*-orbital energy of the Si-H bonds. The π-relaxation of strains significantly occurs in the small rings. Unsaturated small silicon ring molecules are less strained than the saturated ones and the unsaturated carbon congeners. We calculated a series of polycyclic silicon molecules to confirm the π-relaxation and suggested that some unknown molecules could be prepared due to the low strain.