Completely stereoselective synthesis of all four stereoisomeric 1-carbamoyloxy-1,3-alkadienes via anti-diastereoselective homoaldol reaction from aldehydes and a single carbon-three-unit

Lithiation of both ($\text{Z}$)- and ($\text{E}$)-3-trimethylsilyl-2-propenyl $\text{N}$,$\text{N}$-diisopropyl carbamate 2 affords the (2$\text{E}$) -lithium compound 3. Aluminium- or titanium-mediated addition to aldehydes, 4 gives (1$\text{E}$)-(3$\text{R}$*4$\text{S}$*)-enol carbamates 7. A stereospecific Peterson elimination (borontriflouride- or base-mediated) introduces the second double bond either with (3$\text{E}$)- or with (3$\text{Z}$)-configuration. So just by reagent selection for each of the two steps, (1$\text{E}$,3$\text{E}$)-, (1$\text{E}$,3$\text{Z}$)-, (1$\text{Z}$,3$\text{E}$)-, or (1$\text{Z}$,3$\text{Z}$)- dienes 8 - 11, respectively, are prepared with stereoselectivities up to > 99.7%     

Stereochemical studies 83 saturated heterocycles 76 : Preparation and conformational study of partially saturated 3,1-benzoxazines, 3,1-benzoxazin-2-ones and 3,1-benzoxazine-2-thiones

The $\text{cis}$- and $\text{trans}$-2-amino-4-cyclohexene-1-carboxylic acids $\text{1}$ and $\text{3}$ react with imidates to give the condensed-skeleton, bicyclic $\text{cis}$- and $\text{trans}$-pyrimidin-4-ones $\text{8}$ and $\text{9}$. The amino acids $\text{1}$ and $\text{3}$ were reduced to the $\text{cis}$-and $\text{trans}$-1, 3-aminoalcohoIs $\text{6}$ and $\text{7}$, which were cyclized by means of imidates to the bicyclic tetrahydro-4$\text{H}$-3,1-benzoxazines $\text{10}$ and $\text{11}$, or were converted, $\text{via}$ the corresponding carbamates $\text{14}$ and $\text{15}$ into the tetrahydro-4$\text{H}$-3,1-benzoxazin-2(1$\text{H}$)-ones $\text{16}$ and $\text{17}$. The 2-thioxo analogues $\text{18}$ and $\text{19}$ were prepared by cyclization of the dithiocarbamates obtained from the aminoalcohols $\text{6}$ and $\text{7}$ by treatment with carbon disulphide. The $\text{trans}$-aminoalcohol $\text{7}$ and its saturated analogue reacted with $\text{p}$-chlorobenzaldehyde to furnish the hexahydro $\text{13}$ and octahydro-4$\text{H}$-3,1-benzoxazine $\text{13a}$, respectively. ¹H and ¹³C NMR studies showed that, similarly to the earlier-investigated analogues containing oxygen or unsubstituted nitrogen at position 1, the synthesized $\text{cis}$ isomrs $\text{8}$, $\text{10}$, $\text{16}$ and $\text{18}$ occurred as the preferred conformer in the heterocyclic twist inverse form of $\text{N}$-inside type ($\text{quasiaxial}$ C₆-N bond) (B). In the $\text{trans}$ isomers containing a saturated C-2 atom ($\text{13}$ and $\text{13a}$), H-2 and H-6 are in $\text{cis}$ relative positions.     

A convenient synthesis of flindersine,atanine and their analogues

A new synthesis of the pyranoquinolone alkaloids flindersine ($\text{8a}$), 8-methoxyflindersine ($\text{8c}$), N-methylflindersine ($\text{9a}$), zanthobunglanine ($\text{9c}$) oricine ($\text{9d}$) and veprisine ($\text{9e}$) and the prenylquinolone alkaloids atanine ($\text{13a}$), preskimmianine ($\text{13e}$) N-methylatanine ($\text{14a}$), O-methylglycosolone ($\text{14c}$) and N-methylpreskimmianine ($\text{14e}$) is described.     

The resolution of racemic 2-alkyl-1-aminocyclopropane-1-carboxylic acids

Practical procedures for the resolution of racemic modification of (1$\text{R}$, 2$\text{S}$)-and (1$\text{S}$, 2$\text{R}$)-1-amino-2-ethylcyclopropane-1-carboxylic acid $\text{1a}$,$\text{b}$,(1$\text{R}$, 2$\text{S}$)- and (1$\text{S}$, 2$\text{R}$)-1-amino-2-methylcyclopropane-1-carboxylic acid $\text{2a}$,$\text{b}$, and (1$\text{R}$, 2$\text{R}$)- and (1$\text{S}$, 2$\text{S}$)-1-amino-2-methylcyclopropane-1-carboxylic acid $\text{3a}$,$\text{b}$ are described; the structures as $\text{1a}$,$\text{2a}$, and $\text{3a}$ were confirmed by X-ray-crystallographic methods.     

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 ($\text{3}$).     

Photochemical studies. Irradiation induced transformations of 1,2-dihydrophthalides

The photochemical behavior of $\text{cis}$-1,2-dihydrophthalide ($\text{1}$) and its 1,2-trimethylene derivative ($\text{4}$) was studied. Besides bicyclo[2.2.0]hexene formation in both cases, ($\text{1}$) transforms into its $\text{trans}$ isomer ($\text{3}$) whereas ($\text{4}$) undergoes a 1,2-shift to ($\text{7}$).     

Syntheses of enantiomeric dihydropyrans through stereocontrolled intramolecular cycloaddition

Reaction of the cyclic 1, 3-dicarboxylic acid derivatives ($\text{1}$), ($\text{2}$) and ($\text{3}$) with (R)- or (S)-citronellal ($\text{4}$/$\text{5}$) gives the enantiomeric tricyclic dihydropyrans ($\text{10}$), ($\text{11}$), ($\text{12}$) and ($\text{13}$), probably via a 100% stereocontrolled intramolecular cycloaddition.     

Conformational dependence of pyranoid rings 1,2-cis-fused to dioxolane rings on the configuration of the dioxolane rings in acetylated derivati

X-Ray and ¹H N.M.R. studies on pyranoid rings 1,2-$\text{cis}$-fused to dioxolane rings in acetylated $\text{D}$-gluco- and $\text{D}$--galactopyranose derivatives demonstrate that the configuration of the dioxolane ring influences the conformation of the pyranoid ring in the $\text{D}$-gluco but not in the $\text{D}$-galactopyranose series. The crystal structure of 3,4,6-tri-$\text{O}$-acetyl-1,2-$\text{O}$-(R)--(l-cyano-ethylidene)-α-$\text{D}$-glucopyranose ($\text{1}$) and 3,4,6-tri-$\text{O}$-acetyl-1,2-$\text{O}$-($\text{R}$)-(1-cyano-ethylidene)-α-$\text{D}$-galactopyranose ($\text{2}$)have been determined by X-ray analysis. Lattice parameters for $\text{1}$ are a=20.6021 (11), b=8.0438 (2), c=5.5541 (1) Å and β= 95.588 (3)° for a cell with P21 symmetry. These parameters for $\text{2}$ are a=20.3361 (7), b=10.0907 (2), c=18.9115 (5) Å, β =112.399 (2)°, C2, with two crystallographycally independent molecules. The conformation of the pyranoid ring in both compounds can be described as flattened ⁴C₁ and that of the dioxolane ring as distorted E₁. The importance of the torsion angles for describing problems of configuration is remarked and the use of relative configurational angles is stressed. The ¹H N.M.R. spectra of $\text{1}$ and $\text{2}$ and 3,4,6-tri-$\text{O}$-acetyl-1,2-O-(S)- and (R)-ethylidene-α-$\text{D}$-glucopyranose ($\text{5}$ and $\text{7}$), 3,4,6-tri-O-acetyl--1,2-O-(S)- and ($\text{R}$)-ethylidene-α-$\text{D}$-galactopyranose ($\text{6}$ and $\text{8}$), and 3,4,6-tri-$\text{O}$-acetyl-1,2-$\text{O}$-($\text{S}$)-and ($\text{R}$)-benzylidene-α-$\text{D}$-glucopyranose ($\text{9}$ and $\text{10}$) have been analyzed by using iterative computer methods and N.O.E. measurements. The results indicate that the major solution conformation of the pyranoid ring of the derivatives in the $\text{D}$-gluco series $\text{1}$, $\text{5}$ and $\text{9}$ may be described as flattened ⁴C₁ and that of $\text{7}$ and $\text{10}$ as ²$\text{S}$₅. The major solution conformation of the pyranoid ring in all compounds in the $\text{D}$-galacto series ($\text{2}$,$\text{4}$,$\text{6}$,$\text{8}$) may be described as flattened ⁴$\text{C}$₁.     

Alicyclische verbindungen-v. darstellung diverser 1,3-butadienylcyclobutane

$\text{cis}$-($\text{3}$) and $\text{trans}$-1,3-Butadienylcyclobutane ($\text{4}$), all-$\text{trans}$-1-(1 ,3-butadieny1 )-2- vinylcyclobutane ($\text{10}$), and all-$\text{trans}$-1,2-bis(1,3-butadienyl)cyclobutane ($\text{15}$) have been prepared from readily available starting materials, and pyrolyzed to various cyclohexenes.     

Acid catalyzed isomerization of bicyclic alkenes: a facile betweenanene synthesis

Isomerization of $\text{cis}$-bicyclo[10.8.0]eicos-1(12)-ene ($\text{1a}$) and $\text{cis}$-bicyclo[10.10.0]docos-1(12)-ene ($\text{1b}$) to [10.8]- and [10.10]betweenanene ($\text{2a}$ and $\text{2b}$) has been effected by sulfuric acid. In both cases, the betweenanene isomers were found to predominate at equilibrium (70/30 $\text{2a}$/$\text{1a}$ and 95/5> $\text{2b}$/$\text{1b}$).     

Stereoselektive synthese von α-glucosiden mit 1,1′ -diacetal-struktur

Reaction of ($\text{1b}$) and ($\text{1d}$) with the acetal ($\text{2a}$) in presence of trimethylsilyl trifluoromethanesulfonate at ?70° C gives the α-glucosides ($\text{3a}$) and ($\text{4a}$), whereas ($\text{1a}$) and ($\text{1c}$) lead to the β-glucosides ($\text{4c}$) and ($\text{4b}$). At 0° C reaction of ($\text{1a}$) with the acetals ($\text{2b-g}$) gives exclusively the α-glucosides ($\text{3b-g}$).     

Conversion of 6-protoilludene into illudin-M and -S by omphalotusolearius

Deuterium labeled $\text{dl}$-6-protoilludene ($\text{7}$) was synthesized and fed to the illudin-producing fungus $\text{Omphalotus}$$\text{olearius}$ (ATCC 11719). The hydrocarbon ($\text{7}$) was incorporated into illudin-M ($\text{2}$) and -S ($\text{3}$).     

Cycloaddition reactions of 2,3-didehydrothiophene generated by flow vacuum thermolysis of thiophene-2,3-dicarboxylic anhydride

Flow vacuum thermolysis (FVT) of thiophene-2,3-dicarboxylic anhydride ($\text{2}$) in the presence of 2,3-dimethylbutadiene ($\text{6}$) gives, in addition to 5,6-dimethylthianaphthene ($\text{9}$). small quantities of a dihydrodimethylthianaphthene ($\text{12}$) and another dimethylthianaphthene ($\text{13}$) which is probably also formed by dehydrogenation of $\text{12}$ with chloranil. The partial structures of these minor products are consistent with their being formed by a [2+2]-cycloaddition between $\text{6}$ and an intermediate aryne, 2,3-didehydrothiophene ($\text{1}$), followed by a rearrangement of the resulting adduct $\text{11}$ and dehydrogenation. FVT of $\text{2}$ in the presence of 2,5- ($\text{17b}$) or 3,4-dimethylthiophene ($\text{17c}$) also gave a mixture of the dimethylthianaphthenes ($\text{18}$$\text{22}$, $\text{23}$) which can be rationalized as arising by a [4+2]- and two [2+2]-cycloadditions of the aryne $\text{1}$ to the thiophenes $\text{17}$ with subsequent desulfurization. The lack of equilibration of the products $\text{18}$, $\text{22}$ and $\text{23}$, was demonstrated and their origin as a function of the structure and reactivity of the aryne $\text{1}$ discussed.     

Stereoselective syntheses of substituted methyl (Z,E,E)-deca-2,7.9-trienoates and substituted methyl (Z,E,E)-undeca-2,8,10-trienoates

Lindlar hydrogenation of substituted methyl ($\text{E}$,$\text{E}$)-deca-7,9-dien-2-ynoates and substituted methyl ($\text{E}$,$\text{E}$)-undeca-8,10-dien-2-ynoates affords selectively the corresponding ($\text{Z}$,$\text{E}$,$\text{E}$)-trienes.     

On cyclopentadienone-ketals and their dimers. A novel rearrangement of α,β-unsaturated ketone dialkyl ketals

The dimers $\text{2a}$ & b) of dimethyl- and diethylcyclopentadienone ketals($\text{1a}$ & b) undergo a novel 1,3-alkoxy-rearrangement to $\text{4}$(a & b). Mild hydrolysis of $\text{2}$ or $\text{3}$ gives the monoketones ($\text{3}$a or b). On strong acid catalysed hydrolysis $\text{2}$, $\text{3}$ or $\text{4}$ afford the cyclopentadienone-dimer($\text{6}$.     

Substituted cyclononatetraenes and nonafulvenes

Reaction of $\text{cis}$,$\text{cis}$,$\text{cis}$,$\text{cis}$-[9]annulene anion ($\text{1}$) with electrophiles ($\text{2a}$-$\text{d}$) leads to substituted $\text{cis}$,$\text{cis}$,$\text{cis}$,$\text{cis}$-1,3,5,7-cyclononatetraenes ($\text{3a}$-$\text{d}$) which are precursors for the preparation of 10- and 10,10′-donor-substituted nonafulvenes (e.g. $\text{7b′}$$\text{e′}$). The influence of solvent and temperature on the ¹H-nmr spectra of the nonafulvenes $\text{7b′}$-$\text{h′}$ has been investigated.     

X-ray structure determinations of the solid state conformations of tri-o-carvacrotide and of tri-3- and tri-6-methylthiosalicylides

In the solid state, tri-6-methylthiosalicylide ($\text{5}$) adopts only $\text{one}$ helical conformation, tri-3-methylthiosalicylide ($\text{4}$) exists as $\text{both}$ enantiomeric helical conformations, and tri-$\text{o}$-carvacrotide ($\text{2}$) provides the first example of the unique situation where $\text{both}$ enantiomeric propeller conformations and $\text{both}$ enantiomeric helical conformations coexist.     

Oxidative decarboxylation of [n.2.2]propellane carboxylic acids with lead tetraacetate. rearrangement approach to bicyclo [n.2.2.]bridgehead alkenes.

Oxidative decarboxylation of [n.2.2]propellane carboxylic acids ($\text{1a}$-$\text{c}$) with lead tetraacetate gave the bicyclic acetates ($\text{2b}$, $\text{c}$) having a bridgehead double bond and/or the tricyclic acetates ($\text{3a}$, $\text{b}$) in good yields. Vapor phase thermolysis of $\text{3a}$ or $\text{3b}$ afforded the bridgehead olefin $\text{2a}$ or $\text{2b}$ quantatively.     

Reactions of cyclo-octatetraene and its derivatives - X: 1,2,3,8-Tetraphenylcyclo-octatetraene and 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene

The reaction of tetracyclone $\text{1b}$ with the cyclo-octatetraene-dimethyl acetylenedicarboxylate adduct $\text{2}$ at $\text{ca}$. 110° produces, in addition to the $\text{exo}$[4+2] Π cycloadduct $\text{3b}$ (49%), 1,2,3,8-tetraphenylcyclo-octatraene $\text{5}$ (11%), together with the diketone $\text{11}$ (5%). In a similar reaction with the esterified cyclo-octatetraene-maleic anhydride adduct $\text{13a}$, the major product $\text{14}$ (82%) is accompanied by the cyclohexa-1,3-diene $\text{15}$ and the dihydrosemibullvalene derivative $\text{16}$. Thermolysis of $\text{3b}$ at $\text{ca}$. 145° leads to the cyclobutene $\text{12}$., which on catalytic hydrogonation followed by decarbonylation at 180°–190° gives 2,3,4,5-tetraphenylcyclo-octa-1,3,5-triene $\text{19}$. Attempted thermal conversion of $\text{19}$ into a dihydrosemibullvalene failed.     

Pheromone XXXVII. Eine stereospezifische synthese der komponenten des sexualpheromons von antherea polyphemus, (E)-6,(Z)-11-hexadecadienylacetat und (E)-6,(Z)-11-hexadecadienal.

Starting from the aldehydes $\text{2}$ and $\text{9}$ the acetylene $\text{16}$ is prepared via the borane $\text{15}$ by means of a combined Wittig reaction-hydroboration reaction sequence. $\text{16}$ may be converted into the (E)-6,(Z)-11-hexadecadienylacetate ($\text{18}$) and the corresponding aldehyde $\text{19}$. The synthetic route proceeds with high stereospecifity (isomeric purity of $\text{18}$ and $\text{19}$ ? 97%).