Synthesis and conformational properties of 5,7-disubstituted [3.3] Metacyclo (2,5) thiophenophane-1,12-diones

The title compounds showed unique conformational equilibria which were dependent upon the substituents in the 5,7-positions, the predominant conformers being in a $\text{syn}$ O,S,O-$\text{cis}$,$\text{cis}$ conformation with a highly deformed thiophene-2,5-dicarbonyl moiety.     

Aza [3.1.1] propellane durch diels-alder-addition von bicyclo [1.1.0] but-1 (3)-en-derivaten an isoindole

The reaction of the halobicyclobutane derivatives $\text{1}$ and $\text{2}$ with LDA in the presence of isoindoles afforded the azapropellanes $\text{4}$ and $\text{5}$ via the bicyclobutene intermediates $\text{6}$ and $\text{7}$, respectively.     

Anti-[3.3]metacyclophane quinhydrones: synthesis,charge-transfer absorption and thermal rearrangement to syn-stereoisomers

The synthesis of $\text{anti}$-[3.3]metacyclophane quinhydrones and their thermal rearrangement to $\text{syn}$-stereoisomers are described. Charge-transfer absorptions are discussed under the aspect of different donor-acceptor orientations.     

Acid-catalysed reactions of 3,5-dialkyl-spiro[2.5]Octa-2,5-dien-4-ones

Acid-catalysed ring opening of the spirodienones ($\text{2a}$) and ($\text{2b}$) using p-toluene-sulphonic acid affords the styrène derivatives ($\text{3a}$) and ($\text{3b}$), while treatment with acetic anhydride/H₂SO₄ affords the furan derivatives ($\text{4a}$) and ($\text{4b}$).     

3-Hydroxy-1,4-diphenyl-7-oxabicyclo[4.1.0]hept-3-ene-2,5-dione. A microbial product from streptomyces species (AAA566)

The epoxyenedione 1a has been isolated from a strain $\text{Streptomyces}$ and its structure has been established by nmr spectroscopy and by its conversion to 2,5-diphenyl-3,4-dihydroxyphenol. Selective hetero J-resolved nmr spectroscopy played a pivotal role in the structure elucidation.     

Photocyclization of n-[ω-(cycloalken-1-yl)alkyl]-and n-[ω-(inden-3-yl)alkyl]phthalimides : Synthesis of spiro-nitrogen multicyclic systems

Photolysis of the N-[ω-(cycloalken-1-yl)alkyl]phthalimides 6b-$\text{e}$ in each case gave a pair of stereoisomers of spiro-nitrogen multicyclic systems (9b-$\text{e}$) in moderate yields, whose stereochemistry was determined by means of chemical and spectroscopic analyses. Similarly, in N-[ω-(inden-3-yl)alkyl]-phthalimides (8), spiro-nitrogen macrocycles up to 13-membered 13a-$\text{c}$ were obtained in good yields     

Characterization of 4-(2,3-diphenylcyclopropenylidene)cyclohexa-2,5-dienone. Highly polarized 6,7-diphenyl[3.6]q́uinaren-3-one

The title quinarenone 2 has a pronounced contribution of the dipolar resonance structure to the ground state, and the three-membered ring of $\text{2}$ is more diatropic than that of diphenylcyclopropenone. The quinarenone 2 exists in equilibrium with its oligomer in solution. The excited state properties of 2 have also been described.     

Transposition des oximies de la 2H-naptho [1,8-bc] pyrannone-3 et de la 2H-benzo [b] furannone-3

Refluxing the oximes ($\text{2}$) of naphtho-[1,8-bc] pyran-3(2H)-one and ($\text{6}$) of 3 (2H)-benzofuranone with alcoholic hydrogen chloride give the corresponding α-alkoxy-ketones $\text{3}$, $\text{4}$, $\text{5}$ and α-chloroketone $\text{7}$ respectively. This transformation appears to be related to the acid conversion of N-aryhydroxylamines to o. and p. substituted anilines (BAMBERGER réarrangement.     

[1.1.1.1.1]paracyclophane and [1.1.1.1.1.1]paracyclophane

The first syntheses of [1.1.1.1.1]paracyclophane ($\text{1}$) and [1.1.1.1.1.1]paracyclophane ($\text{2}$) are described, featuring a trifluoroacetic acid promoted Friedel-Crafts cycloalkylation as the final step.     

[2]Paracyclo[2](3,7)-p-tropoquinonophane

The title compound $\text{1}$ a novel cyclophane containing p-tropoquinone, was synthesized starting from 5-methoxytropolone and its physical properties were discussed comparing with those of 3,7-dimethyl-p-tropoquinone and p-benzoquinonophane. The reduced quinone character exhibited by $\text{1}$ was ascribed to the intramolecular CT interaction and the deformation of the quinone ring.     

The 2-(methylthiomethoxy)ethoxycarbonyl [mtmec] protecting group

Alcohols (ROH) may be converted into their MTMEC derivatives ($\text{6}$) by acylation with 2-(methylthiomethoxy)ethoxycarbonyl chloride ($\text{5}$); the MTMEC “protected protecting group” may be removed by treatment first with Hg(II) perchlorate in the presence of 2,4,6-collidine or pyridine in acetone-water solution, followed by hydrolysis under very mild basic conditions.     

Stereochemistry of electrophilic addition to dimethyl tricyclo[4,2,2,02,5] Deca-3,7-diene-9,10-dicarboxylate. Molecular structure of Hg(OAc)2-addition product

The molecular structure of the $\text{trans}$ addition product of Hg(OAc)₂ to diester $\text{1}$ has been determined by X-ray diffraction (represented by formula $\text{3}$) which leads to a revision of previously claimed $\text{cis}$-additions in this series.     

BH3 THF reduction of 3-methylisoxazolo [4,5-c]pyridines

3-Methylisoxazolo[4,5-c]pyridine $\text{1}$ on reduction with BH₃:THF gave, via the isolable complex $\text{4}$, the tetrahydroisoxazolopyridine $\text{5}$. The presence of two chlorine atoms at the 4 and 6 positions directed borane attact to the isoxazole ring, yielding the aminoethylpyridine $\text{8}$. Both types of reduction were obtained with 6-chloroisoxazolo[4,5-c]pyridine $\text{7}$.     

The [ν]-M relationship for linear polydimethylsiloxane (PDMS)

Weight-average molecular weights for PDMS fractions were determined by light scattering and the Archibald method in the range of 3000–300,000; the [ν]-M? relationship for toluene, 25°, was found to be

$\text{[?]=1.87 × 10}{}^{\mathrm{?2}}\text{M}{}_{\mathrm{<mtext>w</mtext>}}{}^{03658}\text{,}\text{cm3/g}$

This relationship was compared with those previously used. No upward curvature of the linear relation, log $\text{[ν] = ?(}\text{M}\text{)}$, at lower molecular weights was observed. Over the whole range of molecular weights, the [ν]-values in toluene were higher than [ν]_θ-values in bromocyclohexane at 28°.     

Thermolysis of [1,2,4]triazolo[1,5-a]pyrimidine n-ylides

5,7-Dimethyl[1,2,4]triazolo[1,5-a]pyrimidinio-3-phenacylide ($\text{3}$) generated by the reaction of an iminium salt ($\text{2}$) with 1 eq. of triethylamine, underwent a new thermal ring cleavage of the triazole moiety to give the pyrimidine derivative. However reaction of $\text{2}$ with 2 eq. of triethylamine afforded the 2-iminooxazoline derivative. The iminooxazoline reacted with nucleophiles such as alcohols or amines to give imidazoles.     

Conversion of 3-cyclopentenyl hydroperoxide into 5-substituted-2,3-dioxabicyclo[2.2.1]heptanes

3-Cyclopentenyl hydroperoxide $\text{8}$ has been prepared from cyclopentadiene via hydroboration and autoxidation. Bromination of $\text{8}$ followed by treatment with an appropriate silver salt has afforded the 5-substituted-2,3-dioxabicyclo[2.2.1] heptanes $\text{11}$ ($\text{endo}$-bromo), $\text{13}$ ($\text{exo}$-bromo), and $\text{12}$ ($\text{exo}$-trifluoroacetoxy).     

Synthesis of (4.5.5.5]fenestrane and a [4.4.5.5]fenestrane derivative

The synthesis of tetracyclo[5.4.1.0^4,12.0^9.12]dodecan-6-one $\text{12}$ via an intramolelecular photocycloaddition, its reduction to the hydrocarbon $\text{13}$ and its ring-contraction to tetracyclo-[4.4.1.0^3,11.0^9,11]undecane derivative $\text{16}$ is described.     

Nitrogen bridgehead compounds part 16. Facile total synthesis of 7,8-dihydro-13H-indolo[2′,3′:3,4]pyrido[2,1-b]quinazolin-5-one (Rutecarpine).

Rutecarpine $\text{1}$ has been synthetised from hydrazone $\text{2}$, in high yield by Fischer indole synthesis, Hydrazone $\text{2}$ has been prepared from $\text{3}$ with benzenediazonium chloride or $\text{5}$ with phenylhydrazine. $\text{2}$ Shows a solvent dependent E-Z isomerism.     

Terpenes and terpene derivatives - XV. [1 ] Synthesis of 4,8-dimethyl-2-(2-methyl-1-propenyl)--1-oxaspiro(4.5]dec-7-ene (“bisabolene oxide”)

Starting from the ketones $\text{3}$ and $\text{4}$ the synthesis of six spiro ethers with an l-oxaspiro[4.5]decane skeleton is described. Five of them, $\text{9a}$,$\text{b}$, $\text{10a}$,$\text{19}$ and $\text{19}$ represent typical partial structures of the sesquiterpenoid spiro ether $\text{1}$. The unambiguous synthesis of $\text{1}$ shows a previous assignment of “'bisabolene oxide“' to structure $\text{1}$ to be wrong.     

Methylated multibridged [2n]cyclophanes. All alternate synthesis of [26](1,2,3,4,5,6) cyclophane (superphane)

A sequence of formylation followed by a carbene insertion reaction has led to the stepwise introduction of additional ethano bridges into 4,5,7,8- tetramethyl [2₂](1,4)cyclophane ($\text{1}$), providing syntheses of 5,7,8-trimethyl- [2₃](l,2,4)cyclophane ($\text{6}$), a mixture of 5,8-dimethyl[2₄(1,2,4,5)cyclophane ($\text{10}$) and 5,7-dimethyl[2₄(1,2,3,5)cyclophane ($\text{11}$, and-4-methyl[2₅](1,2,3,4,5)-cyclophane ($\text{14}$). This route to $\text{14}$ completes a formal eight-step synthesis of [2₆](1,2,3,4,5,6)cyclophane ($\text{15}$, superphane) with an overall yield of 17%. A Birch reduction of $\text{6}$ readily gave 12,15-dihydro-5,7,8-trimethyl[2₃](1,2,4)-cyclophane ($\text{7}$) in 85% yield.