absolute configuration of the k-region 4,5-dihydrodiols and 4,5-oxide of benzo[a]pyrene

Application of the exciton chirality rule has allowed assignment of absolute configuration to (+)-$\text{trans}$-(4R,5R)-dihydroxy-4,5-dihydrobenzo[a]pyrene, a mammalian metabolite of the hydrocarbon. The cis 4,5-dlhydrodiol and 4,5-oxide are also assigned based on correlation with the trans dihydrodiol.     

New synthesis of benzo [a]quinolizidin-2-ones via protected 2-aryl-4-piperidones

A new synthesis of 9,10-dimethoxy-1,3,4,6,7,11b-hexahydro-2H-benzo aquinolizin-2-one ($\text{1a}$ and its 3-ethyl derivative $\text{1b}$ via the corresponding 2-(3,4-dimethoxyphenyl)-4-piperidone ethylene acetals $\text{7}$ is reported. Alkylation of 2-arylpipendires $\text{7}$ with 2-bromoethanol followed by oxidation of the resulting amino alcohols $\text{9}$ with oxalyl chloride and dimethyl sulfoxide afforded the aldehydes $\text{10}$, which were cyclized with hydrochloric acid to give 7-hydroxybenzo[α]quinolizidines $\text{11}$. The reduction of $\text{1}$ with trinethylsilane and subsequent acid hydrolysis led to benzo aquinolizidin-2-ones $\text{1}$.     

Studies in azide chemistry. Part 12. One-pot conversion of 4-azidotetrafluoropyridine to 1,3,4-trifluoro-7,9-dimethyl-11H-pyrido[4,3-c]benzo[1,2]diazepine

Thermolysis of 4-azidotetrafluoropyridine in the presence of an excess of mesidine at 170 °C yields tetrafluoro-4-(2,4,6-trimethylphenylazo)- pyridine, which undergoes intramolecular dehydrofluorination $\text{in situ}$ to provide 1,3,4-trifluoro-7,9-dimethyl-11$\text{H}$-pyrido[4,3-$\text{c}$]benzo[1,2]diazepine.     

[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.     

Formation of benzo[a]phenoxazine derivatives by triethylphosphite-induced deoxygenation of 1-(2-nitrophenoxy) and 2-(2-nitrophenoxy)naphthalenes

Reaction of 1-(2-nitrophenoxy)naphthalene or its β-isomer $\text{7}$ with triethylphosphite produces benzo[a]phenoxazines $\text{8}$ and $\text{10}$, through the intermediate $\text{6}$.     

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.     

Models of folate coenzymes 13 : Syntheses of benzo[a]quinolizine and indolo[2,3-a]quinolizine derivatives via carbon fragment transfer from folate coenzyme models

Anions of β,β-disubstituted acetyl acetates ($\text{2}$, CH₂COCR₁R₂COOR₃; R₁= R₂ = Me₂ R₁ = Et, R₂ = COOMe, R₁ = Et, R₂ = SPh) add to 1-tosyl-3,4,4-trimethyl-Δ -imidazolinium iodide ($\text{3}$) to give the corresponding imidazolines ($\text{4}$), which are regarded as models of methylenetetrahydrofolate These models transfer C(2) of the imidazalodine -with its appended carbon fragment- to tryptamine and 2-(3,4-dimethoxybenzene)ethyl amine to yield enaminoketo ester intermediates which can be converted into benzo[a]quinolizine and indolo[2,3-a]quinolizine derivatives, respectively, in two cyclization steps. The intermediate derived from transfer of carbon fragment CH-CH₂COC(SPh) (Et) COOMe to tryptamine exhibits reactions which involve nucleophilic displacement at a sulfur atom of a thio ether bond.     

Cycl[4.2.2]azinium salts

Cycl[4.2.2]azinium salts $\text{3}$, $\text{9}$ and $\text{11}$ have been synthesized and shown to be diatropic.     

The [4.4.4.4]Fenestranes and[2.2.2.2]paddlane. Prospects for the realization of planar tetracoordinate carbon?

Semi-empirical (MINDO/3 and UNDO) MO calculations on highly strained planar tetracoordinate carbon candidates indicate the central carbons in $\text{cis}$- [4.4.4.4] fenestrane ($\text{1}$) to have pyramidal ($\text{1a}$) and in trans-[4.4.4.]fenestrane ($\text{2}$) to have distorted tetrahedral ($\text{2a}$) geometries. In [2.2.2.2]paddlane ($\text{3}$), the two central carbons are pentacoordinate. Each is nearly coplanar with four carbon neighbours; additionally, the two bridgehead carbons are connected by a single bond ($\text{3a}$).     

The 185-nm photochemistry of 2,3-diazabicyclo[2.2.1]heptene and of its denitrogenation products bicyclo[2.1.0]pentane and cyclopentene

The 185-nm denitrogenation of 2,3-diazabicyclo[2.2.1]heptene ($\text{1}$) afforded bicyclo[2.1.0]-pentane ($\text{2}$) and cyclopentene ($\text{3}$) presumably via a “hot” cyclopentane-1,3-diyl diradical ($\text{8}$); 1,4-pentadiene ($\text{4}$) and methylenecyclobutane ($\text{5}$) were secondary products of the 185-nm photolysis of ($\text{2}$) and ($\text{3}$).     

Synthesis of bicyclo[6.2.2] bridgehead dienes

Bicyclo[6.2.2]dodecadienes ($\text{2}$), ($\text{3a}$), and ($\text{3b}$) having two bridgehead double bonds were synthesized by the pyrolysis of the acetate ($\text{1}$).     

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.     

Studies on the formation of [5]metacyclophane

Base induced elimination of HCl from the dichloro[5.3.1]propellane $\text{3a}$ gives a mixture of [5]metacyclophane ($\text{1}$) and tetrahydrocyclopentacyclooctenes ($\text{2}$), while the stereoisomeric $\text{3b}$ affords $\text{1}$ quantitatively.     

[4+2]cycloaddition reactions of triarylphosphaalkene

Cycloaddition reactions of mesityl(diphenyliiifithylene)phosphine ($\text{1}$) were Investigated. With several dienes, no Diels-Alder reactions were oEserved. With azides, diphenyidiazomethane and 2,4,6-trimethylbenzonitrile oxide, the corresponding cycloadducts ($\text{4}$$\text{12}$$\text{17}$$\text{12}$were obtained. In the case of phenyl azide, a competing Staudinger reaction occurred leading to $\text{3}$.     

Benzo-separated pyrazolopyrimidines: Expeditious syntheses of [3,4-g]-and [3,4-h]-linked pyrazoloquinazolinones

Syntheses for pyrazolo[3,4-g]quinazolin-8(7H)-one ($\text{8}$) and its [3,4-h]-analog 11 have been developed involving elaboration of aminoindazolcarboxylic acids $\text{15}$ and $\text{30}$ from correspondingly substituted methylnitroindazols, and subsequent anellation of the pyrimidine ring by v. Niementowski cyclization.     

[2+2]-Cycloadditionen von vinylkationen

The vinylbromides $\text{1a}$ and $\text{1b}$ are allowed to react ith AgBF₄ and AgPF₆ in the presence of various olefins in CH₂Cl₂ as the solvent. Except for the reaction of cyclopentene with $\text{1a}$ all other olefins used, react with vinyl cation $\text{2}$ to form the cycloaddition products $\text{7}$, $\text{8a}$ and $\text{8b}$ in high yields.     

Rearrangement of allyl hexafluoroisopropyl sulfides [1]

The rearrangement of terminal allylic hexafluoroisopropyl sulfides to the internal olefinic sulfide occurs under either photochemical or thermal conditions. In the case of the formation of $\text{E}$ and $\text{Z}$ isomers, the $\text{E}$ isomer was predominant. The rearrangement is suggested as a unimolecular, associative radical mechanism, $\text{via}$ kinetic studies, use of inhibitors, or radical initiator.     

Functionalized 2-azabicyclo[3.3.1]nonanes. IV. synthesis of the indolo[3,2-f]morphan system.

A short route to the 2-azabicyclo[3.3.1]nonan-7-one system is described. Condensation of 4-piperidones with diethyl 2-oxopropylphosphonate, followed by catalytic hydrogenation furnished the corresponding piperidylpropanones $\text{6}$ which were cyclized with mercuric acetate in acetic acid to the target target bicyclic ketones $\text{1}$. The Fischer indole synthesis from $\text{1}$$\text{a}$ afforded regioselectively the indole [3,2-f]morphan $\text{2}$, a new heteromorphan type.     

Isomeric [2.2]metaparacyclophane quinhydrones

The two [2.2]metaparacyclophane quinhydrones $\text{1}$ and $\text{2}$ were synthesized. Structure, stereochemistry and charge-transfer absorptions are discussed.     

A novel benzo[a]quinolizidine rearrangement involving intramolecular carbamyl-chloride-induced cleavage of a tertiary amine

The free base of benzoquinolizidine $\text{3}$ undergoes a facile rearrangement to pyrimidoisoquinoline $\text{4}$, the structure of which was confirmed by x-ray crystallography.The regiospecificity of this novel rearrangement is governed by stereoelectronic factors.