A total synthesis of (±)faranal,the true trail pheromone of pharaoh's ant, monomorium pharaonis

A relatively brief total synthesis of (±)-Faranal [3$\text{SR}$,4$\text{RS}$), (6$\text{E}$,1O$\text{Z}$)-3,4,7, 11-tetramethyl-6,10-tridecadien-l-al] (1) is reported.     

Studies on Chirality Transfer in the [2,3] Sigmatropic Rearrangement of Anions Derived from Trialkylstannylmethyl Allylic Ethers. Stereospecific Synthesis of (2R)-3-Benzyloxy-2-methylpropanol.

Virtually complete chirality transfer is observed in the [2,3] sigmatropic rearrangement of the anion derived from trialkylstanylmethyl ($\text{E}$)- or ($\text{Z}$)-allylic ethers.     

The solution photochemistry of αβ-unsaturated sulphones

1-Phenyl-2-(benzenesulphonyl)-ethylene and 1-phenyl-2-(benzenesulphonyl)-prop-1-ene have been shown to undergo $\text{Z}$,$\text{E}$-photoisomerisation, whereas 2-benzenesulphonylindene readily forms [_π2 + _π2] photoadducts with 2,3-dimethylbut-2-ene, cyclopentene, and cyclohexene.     

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%     

Hexafluorothioacetone based synthesis of fluorinated heterocycles

Cycloadducts of hexafluorothioacetone (HFTA) were prepared in high yield by a CsF catalyzed reaction between readily available 2,2,4,4-tetrakis-(trifluoromethyl)-1,3-dithietane (as a source of HFTA) with conjugated electron-rich hydrocarbon dienes, such as cyclopentadiene, 2,3-dimethylbuta-1,3-diene, cyclohexa-1,3-diene or (1Z,3Z)-cyclohepta-1,3-diene. Cyclohexa-1,4- and (1Z,5Z)-cycloocta-1,5-dienes, also undergo the reaction with in situ generated HFTA, but form the products of insertion of HFTA into the C-H bond of the diene as a result of ene-reaction. The highly selective reaction of HFTA with (1Z,3Z,5Z)-cyclohepta-1,3,5-triene and (1Z,3Z,5Z,7Z)-cycloocta-1,3,5,7-tetraene leads to the formation of cycloadducts derived from exclusive addition of thioacetone to the corresponding bicyclic isomers—bicyclo[4.1.0]hepta-2,4-diene or bicyclo[4.2.0]octa-2,4,7-triene, respectively. The corresponding cycloadducts of HFTA with 2,3-dimethylbutadiene-1,3-cyclohexa-1,3-cyclohexa-1,4-dienes and (1Z,3Z,5Z)-cyclohepta-1,3,5-triene were also prepared by direct reaction of sulfur/hexafluoropropene/KF and the corresponding hydrocarbon substrate at 35-45 °C in DMF.     

Useful synthetic reagents derived from 1-triisopropylsilylpropyne and 1,3bis-[triisopropylsilyl]propyne,direct, stereoselective synthesis of either Z or E enynes

Lithio reagents derived from 1-triisopropylsilylpropyne ($\text{1}$) and 1,3-$\text{bis}$-[triisopropylsilyl]propane ($\text{3}$) are effective for the synthesis of $\text{Z}$ or $\text{E}$ terminal enyne units (CHCHCCH) and for carboncarbon bond formation with halides, aldehydes, ketones, epoxides, and α,β-enones.     

Studies in claisen rearrangement - novel thermal and mercuric trifluroacetate induced transformations of 2,4-di(N-aryl)amino-1,3,5-triazin-6yl-prop-2-y

The thermal rearrangement of 2,4-di(N-aryl)amino-1,3,5-triazin-6yl-prop-2-ynyl ethers $\text{1}$ yield a mixture of 6-methyleneimidazo(1,2-a)-1,3,5-triazine-4-one $\text{6}$ and 6-methylimidazo(1,2-a)-1,3,5-triazine-4-one $\text{7}$, whereas under the influence of mercuric trifluroacetate the ethers $\text{1}$ yield only $\text{6}$, at room temperature. Mechanisms invoking [3,3] sigmatropic rearrangement of ethers $\text{1}$ were proposed to account for the product formation.     

Influence de la longueur d'onde sur la photoisomerisation de derives de l'hexatriene-1,3,5

Kinetic studies of photoisomerization of 1-phenyl 6-methyl-cyclohexa-1,3-diene, and of the four isomeric 5-phenylhepta-1,3,5-trienes, have been performed at 313, 254, 228 and 214 nm. Photoreactions of these compounds are dependent on the wavelength of irradiation. Photolysis at short wavelength of Z,E-5-phenylhepta-1, 3,5-triene initiates a new reaction, sigmatropic [1,5] hydrogen migration, forming an ene-allenic compound. Thermal reactivity data for polyenic compounds supports the assigned structures.     

Thionin oxide as a Possible Intermediate on Periodate Oxidation of 9-Thiabicyclo[6.1.0]nona-2,4,6-triene

9-Thiabicyclo[6.1.0]nona-2,4,6-triene was oxidized at ?15 to ?20°C with sodium periodate in a methanol-water medium. The major isolated product was established as $\text{cis}$3a,7a-dihydrobenzo[b]thiophene-$\text{cis}$-1-oxide, which is best explained as arising from intramolecular cycloaddition of a thionin oxide intermediate.     

Stereospecific synthesis of (5E)-PGE2 by palladium-catalyzed decarboxylative 2-alkenylation of 2-alkenyloxycarbonylated cyclopentanone derivative

(5$\text{E}$)-Prostaglandin E₂ methyl ester was synthesized from ($\text{R}$)-4-$\text{t}$-butyldimethylsiloxy-2-cyclopentenone by $\text{in}$$\text{situ}$ 2-alkenyloxycarbonylation of the organocopper conjugate-addition adduct followed by intramolecular palladium-catalyzed decarboxylative 2-alkenylation. A ($\text{E}$)-2-butenylated cyclopentanone derivative was obtained from either 2-[($\text{E}$)- or ($\text{Z}$)-2-butenyloxy-carbonyl]cyclopentanone derivative under the similar reaction condition.     

Valence isomerization of C9H10hydrocarbons: Photochemical reactions of bicyclo [3.2.2] nona-2,6,8-triene and its dihydro-derivatives

The valence isomerization reaction of bicyclo[3.2.2]nona-2,6,8-triene ($\text{2}$), which photoisomerized to two homologues of semibullvalene, was discussed with the photoreactions of its dihydro-dreivatives, bicyclo[3.2.2]nona-6,8-diene ($\text{3}$) and bicyclo[3.2.2]nona-2,6-diene ($\text{4}$).     

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.     

Conjugate addition of (trimethylstannyl)copper reagents to α,β-acetylenic N,N-dimethylamides. Trapping of the intermediates with electrophiles

A study of the reaction of Me₃SnCu·.Me₂S (1) and [Me₃SnCuSPh]Li (2) with α,β - acetylenic N,N-dimethylamides 3 shows (a) that the overall process can be controlled experimentally so as to produce either N,N-dimethyl ($\text{E}$)-(4) or ($\text{Z}$)-3-trimethylstannyl-2-alkenamides (5), (b) that the initially formed intermediate derived from interaction of 2 and 3 is significantly more stable than that obtained by reaction of 2 and α,β-acetylenic esters, and (c) that the intermediate produced by treating 3 with 1 can be trapped with electrophiles other than proton.     

E- or Z-selective Horner-Wittig reactions of substituted bicyclo[3.3.0]octane-3-ones with chiral phosphonoacetates

The Horner-Wittig reaction of substituted bicyclo[3.3.0]octane-3-ones with chiral phosphonoacetates 2 gave the corresponding unsaturated esters in $\text{E}$/$\text{Z}$-ratios of up to 91 : 9.     

Synthesis of the natural enantiomers of ascochlorin,ascofuranone and ascofuranol

Three fungal metabolites with a common structural feature as prenylated phenols were synthesized in their naturally occurring and optically active forms: ascochlorin [(2'$\text{E}$,4'$\text{E}$,1'$\text{R}$,2'$\text{R}$,6'$\text{R}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[5'-(1',2',6'-trimethyl-3'-oxo-cyclohexyl)-3'-methyl-2', 4'-pentadienyl] benzaldehyde], ascofuranone [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$)-(-)-5-chloro-2, 4-dihydroxy-6-methyl-3-[7'-(3',3'-dimethyl-4'-oxo-2'-oxacyclopentyl)-3',7'-dimethyl -2', 6'-heptadienyl] benzaldehyde] and ascofuranol [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$,4'$\text{S}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[7'-(3', 3'-dimethyl-4'-hydroxy-2'-oxacyclopentyl)-3', 7'-dimethyl-2',6'-hepta-dienyl]benzaldehyde ]. (+)-Ascofuranone and (+)-ascofuranol were also synthesized. By the present synthesis the absolute configuration of the natural (-)-ascofuranol was established as (1'$\text{S}$,4'$\text{S}$).     

Total synthesis of (±)-neoechinulin A,an indole alkaloid containing oxidized diketopiperazine

Protected neoechinulin A ($\text{Z}$ isomer) and its $\text{E}$ isomer were synthesized by condensation of N-bis(methylthiomethyl)cyclo(Ala-Gly) with 2-(1,1-dimethyl-2-propenyl)-1-methoxymethylindole-3-aldehyde; deprotection of both isomers gave neoechinulin A, whose $\text{Z}$ configuration was rigorously established. A novel cyclization of the protected neoechinulin A into a seven-membered cyclic compound was reported.     

Isolation and structural elucidation of heliangolidin,a new sesquiterpene lactone from artemisia canariensis

A new heliangolide has been isolated from aerial parts of $\text{Artemisia canariensis}$, and identified as (6$\text{E}$,10$\text{Z}$)(3$\text{S}$,3a$\text{R}$,4$\text{S}$,lla$\text{R}$)-3a,5,8,11a--tetrahydro-4-acetoxy-3,6, 1O-trimethyl-2,9 (3$\text{H}$, 4$\text{H}$) -cyclodeca[b] furandione. The structural elucidation of the new compound, named heliangolidin, was carried out by spectral means (MS, IR, ¹H and ¹³C NMR, and two dimensional ¹H-¹³C chemical shift correlations) and X-ray diffraction analysis.     

Synthesis of 4″-carboxylated cannabinoids: Stereospecific processes involving ethylidenemalonic ester

4″-Carboxylated-cannabidiol,-Δ¹-and-Δ^1,6-tetrahydrocannabinols and - cannabinol are synthesised. Condensation between aromatic aldehydes and ethylidenemalonic ester gives a 2$\text{E}$,4$\text{E}$-half ester stereospecifically, a reaction which can be used to make 2$\text{E}$-4$\text{E}$- or 2$\text{Z}$,4$\text{E}$-pentadienoates.