Synthesis of functionalized hydroquinones via [Cp*RuCl2]2-catalyzed cocyclization of alkynes, alpha,beta-unsaturated carbonyl compounds, and carbon monoxide

[reaction: see text] Catalytic [2 + 2 + 1 + 1] cocyclization reaction of an alkyne, an alkene, and two molecules of carbon monoxide, leading to functionalized hydroquinones, was studied. Using [Cp*RuCl2]2 as a catalyst, we found that a variety of electron-deficient alkenes, such as alpha,beta-unsaturated ketones, esters, amides, and nitriles, can be employed as an alkene coupling partner to give the corresponding hydroquinones.     

Cationic polymerization of α,β-disubstituted olefins. V. Reactivity of propenyl alkyl ethers in cationic polymerization

To elucidate the effect of the introduction of a methyl group in the β-position of a vinyl monomer, propenyl alkyl ethers were copolymerized with vinyl ethers having the same alkoxy group. Propenyl alkyl ethers with an unbranched alkoxy group (ethyl or n-butyl propenyl ether) were more reactive than the corresponding vinyl ethers. This behavior is quite different from that of β-methylstyrene derivatives. However, propenyl alkyl ethers with branched alkoxy groups at the α carbon atom (isopropyl or tert-butyl propenyl ether) were less reactive than the corresponding vinyl ethers. Also, cis- isomers were more reactive than the trans isomers, regardless of the kind of alkoxy group and the polarity of the solvent.     

Asymmetric sequential Michael reaction: Synthesis of optically active bicyclo[2.2.2]octane derivatives

The sequential Michael reaction of (S)-4,5-di-O-isopropylidenepent-2- enoate and with lithium enolate afforded diastereo- and enantioselectively bicyclo[2.2.2]octane and (or ), respectively. The adducts were efficiently converted into both enantiomeric keto aldehydes (−)- and (+)- .     

Short synthesis of 6-oxoprostaglandin E1 and 6-oxoprostaglandin F1α

6-Oxoprostaglandin E₁ methyl ester was synthesized in a single pot from ($\text{R}$)-4-$\text{t}$-butyldimethylsiloxy-2-cyclopentenone by organocopper conjugate addition with an ω side-chain unit, trapping of the resulting enolate with 6-methoxycarbonyl-2-nitrohex-1-ene, and treatment with aqueous titanium(III) trichloride. Hydrolysis of the methyl ester was accomplished by porcine liver esterase. 6-Oxoprostaglandin F_1α, was obtained from 6-nitroprostaglandin E₁ methyl ester in four steps.     

Di-isotacticity of poly(methyl propenyl ether) and double-bond opening of methyl propenyl ether in cationic polymerization

The di-isotacticity of poly(methylpropenyl ether) obtained by the cationic polymerization has been studied by NMR spectra. The NMR spectra of β-methyl protons of the polymer are decoupled from the β-methine proton spectra to determine the di-isotactic fraction in a polymer. The signals of β-methyl protons at 8.78 and 8.89 τ are estimated as spectra based on threo- and erythro-di-isotactic diads, respectively. With BF₃·O(C₂H₅)₂ as a catalyst, the trans monomer yields a crystalline polymer and its structure is threo-di-isotactic. Otherwise, cis monomer produces an amorphous polymer, and it is a mixture of threo- and erythro-di-isotactic structure. From these results, it is concluded that the double bond in trans monomer is opened exclusively in the cis type, and in cis monomer cis- and trans-openings take place at almost the same rate.     

Electronic spectra of 12-S-CIS conformationally locked retinals

The electronic absorption spectra of the four new 12-$\text{s}$-$\text{cis}$-locked retinals (1a–1d) bearing 7-$\text{trans}$, 11-$\text{trans}$ double bond geometries are described and compared with those of analogous 7-$\text{trans}$, 11-$\text{cis}$-geometries (1e–1h) and parent retinals (2a-h).     

Effects of metal salts on polymerization. VI. Photo and thermally catalyzed polymerization of N-vinylimidazole in the presence of metal salts

Polymerization of 2-methyl-1-vinylimidazole (MVI) and 2-ethyl-1-vinylimidazole (EVI) was found to be markedly photosensitized in the presence of oxidizing metal salts such as UO₂(NO₃)₂, Ce(NH₄)₂(NO₃)₆, Hg(CH₃COO)₂, AgNO₃; non-oxidizing metal salts such as Zn^II did not act as photosensitizers. The interaction of monomer with a metal salt is discussed on the basis of infrared and electronic spectroscopy. This photopolymerization is very specific with respect to the kind of monomer. The polymerization of noncomplexing monomer (styrene) is not photosensitized by these metal salts. Consequently, photosensitized electron transfer between monomer and metal salt via complex formation is considered to be the most probable initiation mechanism. Cupric acetate and sodium chlorolaurate, which have been reported as efficient initiators for the polymerization of vinylpyridine and N-vinylcarbazole, respectively, act as linear terminators of growing radicals. The radical polymerizability of the zinc complex of MVI was studied by means of copolymerization with styrene. The reduction of the reactivity of MVI on complexing was explained by correlating with the spectroscopic observations. Because the polymerization system is heterogeneous, a detailed discussion was not possible.     

Cross-coupling of alkenyl,aryl or allylic selenides and grignard reagents catalyzed by nickel-phosphine complexes

Alkenyl, aryl or allylic selenides smoothly couple with Grignard reagents in the presence of Ni(II)-phosphine complexes as catalysts to afford the corresponding unsaturated compounds in good yields. The reactivity order of coupling reaction with BuMgBr catalyzed by NiCl₂ [Ph₂PCH₂CH₂CH₂PPh₂] was found to be PhSeMe « PhCl > PhSMe by the competitive reactions.     

Cationic polymerization of cyclic olefins

The polymerization and the polymerizabilities of indene, benzofuran, and 1,2-dihydronaphthalene are discussed from the point of view of ring strain, ring stabilization, and steric hindrance in the transition state. Monomer reactivities of these olefins were estimated from copolymerization with styrene and from the rate of addition of iodine bromide in acetic acid. Rates and degrees of polymerization are compared with monomer reactivities and resonance energies of indene, 1,2-dihydronaphthalene, and benzofuran as a measure of ring strain and stabilization. It is found that indence is 1.5–2.0 times more reactive than styrene. This high reactivity of indene is attributed to the ring strain in the monomer state and to the low amount of steric hindrance in the transition state of the coplanar five-membered cyclic olefin. 1,2-Dihydronaphthalene is strained and therefore reactive, but propagation to higher molecular weight products is impeded due to the steric hindrance. The reactivity of benzofuran is decreased by conjugative stabilization of C?C double bonds at the reaction site.     

Biological stereoselective reduction of 3,3,5-trimethylcyclohexanone by Glomerella cingulata

The microbial transformation of 3,3,5-trimethylcyclohexanone was investigated using the plant pathogenic fungus, Glomerella cingulata. With this organism 3,3,5-trimethylcyclohexanone gave the corresponding cis- and trans-3,3,5-trimethylcyclohexanols with the ratio of 20:1 forming the cis-isomer highly stereoselectively, upon 5 days incubation together with 3,3,5-trimethyl-2-cyclohexen-1-one (isophrone) as a minor product.