Novel copper(I) chloride-assisted coupling reaction of 1-chloro-1-aryloyl-3,3-diarylallene to afford 3,7-dioxa-2,6-diaryl-4,8-bis(diarylmethylene)bicyclo[3.3.O]octa-1,5-diene and 1,1,4,4-tetraaryl-3,6-diaryloylhexa-1,2-diene-5-yne,and thermal cyclization of the latter to a fulvene

A novel CuCl-assisted coupling reaction of 1-chloro-1-aryloyl-3,3-diarylallene ($\text{5}$) and two new thermal cyclization reactions of 1,1,4,4-tetraaryl-3,6-diaryloylhexa-1,2-diene-5-yne ($\text{7}$) are described.     

Wittig and horner-wittig coupling reactions of 2-substituted cyclic ethers and their application to spiroketal synthesis

Wittig and Horner-Wittig coupling reactions of tetrahydropyran or tetrahydrofuran 2-triphenylphosphonium salts or 2-diphenylphosphine oxides with aldehydes and lactols affords good yields of the corresponding enol ethers. In selected examples these enol ether products may be further converted to spiroketals some of which are natural pheromones derived from $\text{Dacus oleae}$ and $\text{Paravespula vulgaris}$.     

19F-19F Coupling constants in the azole series. Synthesis of 3,4-, 4,5-, and 3,5-difluoropyrazoles

Stepwise syntheses of difluoroazoles $\text{1}$, $\text{2}$, and $\text{3}$ have been performed. The J_FF coupling constants are reported for the first time. Surprisingly, no coupling between F₄ and F₅ is observed.     

Nucleophilic reaction of fluoroolefins. V. Regioselectivity and stereochemistry in the reactios of 1-phenylpentafluoropropenes with lithium dialkylamides

1-Phenylpentafluoropropenes $\text{1}$ readily react with lithium dialkylamides to give, in most cases, mixtures of 1-aminosubstituted alkenes $\text{2}$ and 2-amino-substituted alkenes $\text{3}$, with the latter being the favoured products. The reactions with bulky lithium diethylamide and lithium 2-methylpiperidinoamide gave exclusively 1-amino-substituted products $\text{2}$. The effect of the increased bulk of N-nucleophiles is opposite to that observed for the reactions of alkenes $\text{1}$ with C-nucleophiles Increasing electronegativity of the phenyl ring substituents in alkenes $\text{1}$ shifts the regioselectivity of the attack of lithium amides towards the C2 carbon atom. The E to Z isomer ratios of enamines $\text{2}$ were found to be time dependent and the slow isomerisation of the kinetic isomers E to the thermodynamic isomers Z was observed, while the ratio of isomers of enamines $\text{3}$ did not change with time.A concerted, single-step process is suggested for the reactions of alkenes $\text{1}$ with lithium dialkylamides, and a tentative explanation of the different stereochemistry of enamines $\text{2}$ and $\text{3}$ is given.     

Total synthesis of clavulones

Total synthesis of clavulones in naturally occurring form has been accomplished by the aldol coupling of the hydroxy-cyclopentenone $\text{2}$ efficiently obtainable from 1,2-bis-trimethylsilyloxycyclopentene ($\text{4}$) by using 1,3-hydroxy transposition via the allylic methanesulfonate $\text{11}$ and the α,β-unsaturated aldehyde $\text{3}$.     

Substituent effects on carbohydrate coupling reactions promoted by insoluble silver salts

Coupling reactions were performed in the α-D-glucopyranosyl bromide series (i.e. compounds $\text{1}$ a–c, $\text{2}$ a, b, $\text{3}$ and $\text{4}$) and the α-D-mannopyranosyl bromide series (i.e. compounds $\text{7}$ a–c, $\text{8}$ a, b, $\text{9}$) with aglycons $\text{5}$ or $\text{10}$ in the presence of insoluble silver salt promotors. (i.e. silver silicate and silver zeolite). The insoluble silver salt promotes the formation of the β-glycosidic linkage, while a non-participating group is present at C-2 of the glycon. It was found that in both series 4-O-acyl functions increase the β/α ratio of the glycosidic bond formation relative to 4-O-alkyl functions, whereas 3-O and 6-O-acyl functions decrease this ratio. We assume that inductive effects are responsible for the influence exerted by 3-O-substituents, but that through-bond interactions are essential for the effects exerted by 4-O and 6-O substituents. Another unexpected finding was that coupling of α-D-mannopyranosyl bromide derivatives gave much higher β/α ratios than the corresponding reactions of α -D-glucopyranosyl bromides.     

Generation and cycloaddition reactions of indole-2,3-quinodimethanes

N-methyl and N-tert-butoxycarbonylindole-2,3-quinodimethanes ($\text{2}$ and $\text{3}$) have been generated and observed to undergo intermolecular cycloaddition reactions with dienophiles.     

Hydrolysis of very reactive methylation agents - a rapid injection N. M. R. investigation.

By use of the recently described Rapid Injection N. M. R. technique it has been possible to measure the hydrolysis rates of $\text{1}$, $\text{2}$, and $\text{3}$ at various temperatures; the activation parameters for these rapid reactions have been determined and discussed.     

The palladium(II)-assisted syntheses of (±)α-(methylenecyclopropyl)glycine and (±)trans-α-(carboxycyclopropyl) glycine,two bioactive amino acids.

Title compounds $\text{1}$ and $\text{2}$ have been synthesized efficiently from β-hydroxyallylglycine derivative $\text{3}$ via the Pd(II)-catalyzed reactions.     

Triplet-mediated coupling of 5-bromo-1,3-dimetrhyluracil to Nb-methoxycarbonyltryptamine involving a double electron transfer

On acetone-sensitization, 5-bromo-1,3-dimethyluracil ($\text{1}$ reacts with N^b-methoxycarbonyltryptamine ($\text{4}$ under the assistance of an electron carrier such as 2-methoxynaphthalene to give a coupling product $\text{6}$. A mechanism involving a double electron transfer via the triplet state of $\text{1}$ is proposed.     

Stereochemistry of organic sulphur compounds. part 13. Configurational assignment of diastereoisomers of 2-methylsulphinyl-1,2-diphenylethanol and of their O-methyl and O-acetyl derivatives

The synthesis, isolation and conformational analysis of the diastereomeric 2-methylsulphinyl-1,2-diphenylethanol and of its $\text{O}$-methyl and $\text{O}$-acetyl derivatives are reported. Chemical correlations and the study of the influence of solvent polarity changes on the coupling constants have permitted the configurational assignment. Lanthanide shift reagents have been used also. to this effect. The role of hydrogen bonding in the hydroxysulphoxides has been evaluated in diluted solutions by IR and NMR spectroscopy. A donor-acceptor interaction between oxygen and sulphur has been invoked to explain the differences in conformational behaviour between epimeric sulphoxides at sulphur atom.     

Synthesis and intramolecular cyclisation of ortho-hydroxy-2,3,3,3-tetrafluoropropiophenone. Formation of 3-fluoro-4-hydroxycoumarin

Acidic hydrolysis of 1-(o-methoxyphenyl)pentafluoropropene $\text{1}$ gave o-hydroxy-2,3,3,3-tetrafluoropropiophenone $\text{2}$ and o-methoxy-2,3,3,3-tetrafluoropropiophenone $\text{3}$. Compound $\text{2}$ when treated with aqueous potassium hydroxide or methanolic sodium methoxide gave 3-fluoro-4-hydroxycoumarin $\text{4}$. Structure of $\text{4}$ has been established by spectral means and some chemical reactions. The cyclisation mechanism of $\text{2}$ is discussed.     

Chemistry of ketene acetals II. A simple route to 2,2-dialkoxytetrahydrofurans, γ-butyrolactones, 2-(5H)-furanones and 2-alkoxy-4,5-dihydrofurans

2,2-Dialkoxytetrahydrofurans $\text{3}$ (a,b) have been synthesized from epoxides $\text{1}$ and ketene acetals $\text{2}$ using ZnCl₂ as a catalyst. By simple reactions compounds $\text{3}$ were converted into γ-butyrolactones $\text{5}$, 2-(5H)-furanones $\text{7}$ and 2-alkoxy-4,5-dihydrofurans $\text{8}$.     

Substituent influence on the indolization with pcl3 of some o,m,p-substituted phenylhydrazones

The indolization of deoxybenzoin $\text{o}$,$\text{m}$,$\text{p}$ (Me, MeO, Cl), $\text{p}$-NO₂ and $\text{m}$-EtO-phenylhydrazones (1) by the above reaction has been examined. All the reactions are carried out at room temperature and high yields of the corresponding indoles (2) are obtained even when -NO₂ substituent is present. In this case longer reaction time is necessary. Alkoxyphenylhydrazones give the corresponding indoles (2) in high yields without showing collateral reactions which indeed are present in several Fischer routes on these derivatives. $\text{m}$-Substituted phenylhydrazones (1) give a mixture of 4- and 6-substituted indoles in which the 6-isomer is always prevalent, a feature not inherent in the Fischer reactions. The regioselectivity is enhanced by the substituent steric hindrance increasing. The reaction can be also carried out at 0°C with a further improvement of its regioselectivity.     

A biogenetically patterned conversion of palmatine into polycarpine

Oxidation of palmatine ($\text{1}$) choride with $\text{m}$-chloroperbenzoic acid in methylene chloride in the presence of sodium bicarbonate at near ?78° C yields polycarpine ($\text{2}$). A new biogenetic route to the aporphines is proposed which does not involve phenolic oxidative coupling, and proceeds through the intermediacy of protoberberinium salts.     

Stereochemistry of the reactions of pinacol allylboronate with two α,β-dialkoxyaldehydes

The stereochemistry of the reactions of pinacol allylboronate $\text{5}$ with α,β-dialkoxyaldehydes $\text{3}$ and $\text{4}$ is described. The results are contrasted with data for the reactions of crotylboronates $\text{1}$ and $\text{2}$ with the same aldehydes.     

Asymmetric synthesis via acetal templates. 12. Highly diastereoselective coupling reactions with a ketene acetal. An efficient,asymmetric synthesis of R-(+)-α-lipoic acid

TiCl₄ catalyzes the essentially quantitative coupling of chiral acetals $\text{1}$ with 1-$\text{t}$-butoxy-1-$\text{t}$-butyldimethylsilyloxyethene $\text{2}$ to generate β-alkoxycarboxylates in which the new asymmetric center is formed with excellent diastereoselection. β-hydroxycarboxylic acids of high ee result from removal of the chiral auxiliary. The procedure has been applied to the synthesis of R-(+)-α-lipoic acid $\text{10.}$     

Diastereoselective cyclisations of chiral α-acyliminium ions

(R,R)-tartaric acid has been converted into (R,R)-dimethoxysuccinimide which after coupling with Z-3-hexenol and 5-hexynol followed by NaBH₄/H^⊕ reduction can be cyclised to optically pure $\text{2c}$ and $\text{4c}$.     

A highly efficient synthetic route to ketones through sequential coupling reactions of grignard reagents with s-phenyl carbonochloridothioate in the presence of nickel or iron catalysts

The sequential coupling reactions of Grignard reagents with $\text{S}$phenyl carbonochloridothioate in the presence of nickel(II) or iron(III) catalysts provides a very mild and straightforward route to symmetrical and unsymmetrical aliphatic and aromatic ketones.     

Organophosphorus chemistry. Part 19. Free-radical addition of dialkyl phosphites to polyfluoro-olefins

An improved procedure for the peroxide-catalysed addition of dialkyl phosphites to tetrafluoroethylene is described, and the reactions of diethylphosphite with chlorotrifluoroethylene, 1,1-difluoroethylene,perfluoropropene, and 3,3,3-trifluoropropene have been investigated and found to yield diethyl 2-chloro-1,1,2-trifluoroethylphosphonate, diethyl 2,2-difluoroethylphosphonate, an 80:20 mixture of diethyl 2$\text{H}$-hexafluoro-$\text{n}$-propylphosphonate and diethyl 1$\text{H}$-hexafluoropropyl-2-phosphonate, and diethyl 3,3,3-trifluoropropyl-1-phosphonate, respectively.