A Wittig reaction on mucochloric and mucobromic acids. Preparation of ethyl (2E, 4Z -4,5-dihalo-2,4-pentadienoates and alkyl 2E -5-bromo-2-penten-4-ynoates

Reaction of mucochloric and mucobromic acid with (ethoxycarbonylmethylene) triphenyl-phosphorane affords the ethyl ester of (2$\text{E}$, 4$\text{Z}$ -4,5-dichloro- and (2$\text{E}$, 4$\text{Z}$) -4, 5-dibromo-2,4-pentadienoic acid respectively; in the latter case ethyl (2$\text{E}$ -5-bromo-2-penten-4-ynoate is formed concomittantly.     

Rotational isomerism between the E and Z forms of o-substituted benzo-N-methyl hydroxamic acids in strong acid

The $\text{E}$∠$\text{Z}$ equilibrium of the cations of benzo hydroxamic acids, in mineral acid, was studied utilizing ¹H NMR spectroscopy, NOEDS and MNDO claculations     

Reaction of superoxo Co(III) complexes with 2,6-di-t-butyl-p-benzoquinone methides

Superoxo Co(III) complexes derived from Co(Salpr) and [Co(CN)₅]^3? reacted with 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone methides to give 2,6-di-$\text{t}$-butyl-$\text{p}$-benzoquinone and 2,6-di-$\text{t}$-butyl-2,5-cyclohexadienonespirooxiranes as the main products, which are considered to result from nucleophilic attack by the superoxo species on the exo double bond of the quinone methides.     

Thermolysis of n-(o-azidobenzoyl)-iminopyridinium ylide: a new route to 3h-indazol-3-one

3$\text{H}$-Indazol-3-one has been generated by thermolysis of $\text{N}$($\text{o}$-azidobenzoyl)iminopyridinium ylide and trapped as its Diels-Alder cycloadducts with several dienes.     

[2+2] Cycloaddition of benzyne to cis,trans- and cis,cis-1,5-cyclooctadiene

The relative rates of formation of $\text{cis}$ and $\text{trans}$ [2+2]cycloadducts of benzyne to $\text{cis}$, $\text{trans}$- and $\text{cis}$, $\text{cis}$-1,5-cyclooctadiene, $\text{trans}$- and $\text{cis}$-cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described.     

Base-induced intramolecular cyclisation of N-(o-azidobenzoyl)-arylamines. A new synthesis of 2-aryl-1,2-dihydro-3H-indazolin-3-ones

In strong base, e.g., sodium hydride in dimethylformamide, $\text{N}$-($\text{o}$-azidobenzoyl)arylamines cyclise in high yield to 2-aryl-1,2-dihydro-3$\text{H}$-indazolin-3-ones.     

Sodium 6-methoxy-(E,E)-3,5-hexadienoate: a useful diene in the aqueous diels-alder reaction

The sensitive dienol ether functionality in sodium 6-methoxy-($\text{E}$,$\text{E}$)-3,5-hexadienoate has been shown to be compatible with the conditions of the aqueous Diels-Alder reaction.     

Synthesis of (1s,5r)-karahana ether and (1s,5r)-karahana lactone,the optically active forms of unique monoterpenes wit

(1$\text{S}$,5$\text{R}$)-(-)-Karahana ether (8,8-dimethyl-2-methylene-6-oxabi-cyclo[ 3.2.1]octane) and (1$\text{S}$,5$\text{R}$)-(-)-karahana lactone (8,8-dimethyl-2-methylene-6-oxabicyclo [3.2.1]octan-7-one) were synthesized from ($\text{S}$)-3-hydroxy-2,2-dimethylcyclo-hexanone. The natural karahana lactone was shown to be almost racemic ($\text{ca}$. 1.3 % e.e.).     

Synthesis and properties of p-C8-bridged hydroquinones and p-benzoquinones

The cycloaddition of the dispiro compound, $\text{2}$, with a variety of 1,3-butadienes affords diacetates of $\text{p}$-C₈-bridged hydroquinones, which are led to the corresponding hydroquinones and $\text{p}$-benzoquinones.     

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).     

Thallium(III) salt-induced olefinic cyclization of o-prenylphenols

Olefinic cyclization of $\text{o}$-prenylphenols ($\text{1}$), ($\text{4}$) and ($\text{6}$) induced by thallium(III) trifluoroacetate was performed.     

Base-induced intramolecular cyclisation of o-azidophenyl sec-alkyl ketones. A new synthesis of 2,2-dialkylindoxyls

$\text{o}$-Azidophenyl $\text{sec}$-alkyl ketones in ethanolic potassium hydroxide at room temperature cyclise in high yield to 2,2-dialkylindoxyls.     

The synthesis of 3-vinylindoles and 11H-5-cyanobenzol[a]carbazole

The synthesis of 3-vinylindoles through Wadsworth Emmons reactions with 3-formyl and 3-acylindoles is described. Although 3-formylindoles react directly with phosphonate derivatives, 3-acylindoles need prior activation by N-sulphonation. 11$\text{H}$-5-Cyanobenzo[$\text{a}$]carbazole has been prepared by the oxidative cycloaddition of $\text{E}$-3-(indol-3′-yl) propenotrile and benzyne.     

A stereocontrolled synthesis of Z and E terminal dienes from pinacol E-1-trimethylsilyl-1-propene-3-boronate

Pinacol $\text{E}$-1-trimethylsilyl-1-propene-3-boronate reacts with aldehydes to form (±)-($\text{R}$*,$\text{S}$*)-3-trimethylsilyl-4-hydroxy-1-alkenes, which can be deoxysilylated stereoselectively to either 98% $\text{Z}$ or 99% $\text{E}$ 1,3-dienes, including the separate components of the red bollworm moth pheromone.     

A total synthesis of (+)-anhydrocannabisativine.

Racemic anhydrocannabisativine has been efficiently synthesized by employing a β -lactam-imino ether coupling reaction. The key to the formation of the tetrahydropyridine moiety of the natural alkaloid is a stereoselective intramolecular conjugate addition of a secondary amino group to a $\text{Z}$,$\text{E}$ dienone.     

Stereospecific synthesis of Z- and E-1 alkoxy-1,3-butadienes

A stereospecific, highly efficient, generally applicable synthesis of $\text{Z}$- and $\text{E}$-1-alkoxy-1,3-butadienes involving dehydrative decarboxylations of 4,5-unsaturated-2-alkoxy-3-hydroxy-carboxylic acids is described.     

Stereoselective synthesis of β-hydroxy-α-methylketones via z- and e-vinyloxyboranes generated directly from cyclohexyl ethyl ketone

$\text{E}$- and $\text{Z}$-dialkylvinyloxyboranes, prepared directly from cyclohexyl ethyl ketone, undergo stereo-selective aldol condensations to provide $\text{threo}$- $\text{erythro}$-β-hydroxy-α-methylketones, respectively.     

Boat-chair conformational preference of exo, exo-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid

The ¹H and ¹³C nmr spectra of $\text{exo}$, $\text{exo}$-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d₆ or alkaline D₂O, clearly show that it exists in a $\text{boat}$-$\text{chair}$-conformation with $\text{equatorial}$ carboxyl groups, thus being the first case of $\text{boat}$-$\text{chair}$ preference of a bicyclo[3.3.1] nonan-9-one due to the presence of $\text{exo}$,$\text{exo}$-2,4- substituents.     

The generation and photochemistry of indenone o-oxide and fluorenone o-oxide in low temperature matrices

The photolysis of diazoindene and diazofluorene at 12K in N₂ matrices containing O₂ has been studied, using i.r. spectroscopy. The carbonyl oxides, indenone $\text{O}$-oxide and fluorenone $\text{O}$-oxide, were formed by the reaction of O₂ with the corresponding carbenes, and under appropriate conditions could be detected as very photolabile species. Photolysis of indenone $\text{O}$-oxide gave indenone and isocoumarin; similar photolysis of fluorenone $\text{O}$-oxide gave fluorenone and dibenzopyran-6-one.     

Diastereoselective synthesis of N-acetyl-D,L-acosamine and N-benzoyl-D,L-ristosamine

N-Acyl derivatives of $\text{D}$,$\text{L}$-acosamine and $\text{D}$,$\text{L}$-ristosamine were synthesized with high stereo selectivity utilizing intramolecular Michael addition of γ- and δ-carbomoyloxy-α,β-unsaturated esters.