v-Triazolines. part XXI. Spiro[bicyclo[2.2.1]hept-2-ene[54']1',2'.s'-triazole]derivatives from cyclopentadiene and 5-amino-4-methylene-v-triazolines

1R^*, 4R^*, 5S^*, 5'S^*-5'-Amino-1'-(4-nitrophenyl)-4',5'-dihydrospiro[bicyclo [2.2. 1]hept-2-ene[5.4]-1',2',3'-triazoles]$\text{2}$ have been obtained both by ?4 +2]-cycloaddition of cyclopentadiene to amino-methylene-1-(4-nitrophenyl)-4,5-dihydro-v-triazoles $\text{1}$ and by [3+2]-cycloaddition of 4-nitrophenylazide to 5-aminomethylene-2-norborenes $\text{4}$. The configuration has been fully established by X-ray crystallographic analysis. The course of the cycloaddition and the thermal behaviour of $\text{2}$ are discussed.     

Dedoublement et configuration absolue de la methyl-3 δ3(3a)-hydrindenone-4.etude de l'isomerisation en methyl-3 δsu3a(7a)-hydrindenone-4.

During the hydrogenation of the Δ^3(3a)-4-hydrindenones $\text{1}$ or $\text{3}$ on Pd or Ni, we observe a shift of the double bond to Δ^3a(7a)-4-hydrindenones $\text{2}$ and $\text{4}$. The absolute configuration established for ketones $\text{1}$ and $\text{2}$ shows that the reaction is a suprafacial process. By deuteriation experiments, we observe that the reaction is irreversible and occurs with a molecular hydrogen exchange.     

Cycloaddition reactions of 1,3-benzothiazines—I. : Reactions of 2-phenyl-4-H and 4-phenyl-2H-1,3-benzothiazine derivatives with substituted acetyl chlorides

6,7-Dimethoxy-2-phenyl-4$\text{H}$-1,3-benzothiazine (1) and 6,7-dimethoxy-4-phenyl-2$\text{H}$-1,3-benzothiazine (2) react with substituted acetyl chlorides to give linearly, and new angularly condensed β-lactam derivatives (4,5). Heating of the latter compounds with hydrogen chloride in anhydrous ethanol leads to the formation of the corresponding 4$\text{H}$- and 2$\text{H}$-1,3-benzothiazinium chloride, respectively. The configurations of these compounds (the mutual positions of the substituents relative to the β-lactam ring) were determined by ¹H and ¹³C studies, also making use of the aromatic solvent-induced shifts.     

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.     

Structural effects on valence tautomerism : VII. An NMR and molecular mechanics study of the steric effects of t-butyl substituents on the cycloheptatriene-norcaradiene equilibrium of 7-cyano-7-m

7-Cyano-7-methylcycloheptatrienes containing one t-butyl group on the 1-position ($\text{2}$) or two t-butyl groups on the 1- and 3-, 1- and 4-, or 1- and 5-positions ($\text{3}$, $\text{4}$, or $\text{5}$, respectively) were synthesized and their cyclo- heptatriene (CHT)-norcaradiene (NCD) equilibria measured by variable-temperature ¹H NMR for CS₂-CD₂Cl₂ solutions. The ¹H NMR chemical shifts of the 7-methyl group indicate that these compounds are composed of essentially one CHT and one NCD tautomer with an endo geometry of the methyl group. The introduction of a t-butyl group at the 1-position of 7-cyano-7-methylcycloheptatriene ($\text{1}$) markedly shifts the equilibrium to the NCD side and the addition of the second t-butyl group further favors the NCD form, with the NCD populations for $\text{2}$, $\text{3}$, $\text{4}$, and $\text{5}$ at 25 °C 70.9, 96.5, 92.3, and 99.3%, respectively. An application of molecular mechanics (MMPI) calculations to various t-butylated CHT-NCD systems suggests that the t-butyl groups sterically destabilize the CHT form more than the NCD form, bringing about increased NCD populations.     

A reinvestigation of asymmetric induction in diels-alder reactions to chiral acrylates.

The chiral induction in the Diels-Alder addition $\text{1}$ → $\text{2}$, assessed reliably by ¹⁹F-NMR-spectroscopy of the endo-esters $\text{4}$, varied between 47 - 93% in favor of the 2-(R)-adducts $\text{2}$ depending on the auxiliary chiral group and the Lewis-acid catalyst.     

Addition products of hydrazine derivatives to azo-alkenes - III. α-phenylhydrazino-phenylhydrazones

The addition of phenylhydrazine to phenylazo-alkenes $\text{4}$ yields α-(1-phenylhydrazino)-phenylhydrazones $\text{1}$. The reaction of phenylhydrazine with α-halogenated carbonyl compounds $\text{5}$ affords either $\text{1}$ or the isomeric α-(2-phenylhydrazino)-phenylhydrazones $\text{2}$. Structures $\text{1}$ and $\text{2}$ (>N-NH₂ and-NH-NH- groups, respectively) can be differentiated by ¹H NMR in DMSO-D₆ solution. Possible pathways of the reactions leading to either $\text{1}$ or$\text{2}$ are discussed. Compounds $\text{1}$ are found to be precursors of phenylosazones $\text{6}$.     

Selenosulfonation of acetylenes. Preparation of novel β-(phenylseleno)vinyl sulfones

Se-Phenyl p-tolueneselenosulfonate ($\text{1}$) undergoes thermal addition to acetylenes to afford β-(phenylseleno)vinyl sulfone adducts $\text{2}$ in a stereo- and regioselective fashion.     

Chiral recognition of alkene and arene hydrocarbons by 1H and 13C NMR. determination of enantiomeric purity

Simultaneous presence of the salt $\text{1}$ and one of the lanthanide complexes (+)-$\text{2}$, (+)-$\text{3}$, or (+)-$\text{4}$ splits ¹H or ¹³C NMR signals of the chiral alkenes $\text{5}$, $\text{6}$, and $\text{8}$ as well as of the chiral arene $\text{7}$; the enantiomeric purity of a mixture of (+)- and (?)-$\text{8}$ was determined successfully.     

A biosynthetic approach to the structure of eumelanins. The isolation of oligomers from 5,6-dihydroxy-1-methylindole.

Enzymic oxidation, or autooxidation at pH 9, or$\text{1}$ led to a mixture of fluorescent products the major of which could be isolated, as the acetyl derivative, and identified as 5,6,5',6'-tetraacetoxy-1,1'-dimethyl-2,4'-biindolyl ($\text{6}$). In the presence of metal cations, e.g. Ni²⁺, autooxidation of $\text{1}$, at pH 7.5, led to the isolation, besides the dimer $\text{6}$ in lower amounts, of two more oligomers which were formulated as 5,6,5',6'-tetracetoxy-1,1'-dimethyl-2,2'-biindolyl ($\text{7}$) and 5,6-diacetoxy-1-methyl-2,4-di-[5',6'-diacetoxy-1'-methy1-2'-indolyl]-indole ($\text{8}$). The unexpected reactivity of $\text{1}$ to undergo oxidative coupling at 2- and 4- position rather than at 3- and 7- position, as previously believed, is discussed in relation to the current views on the structure and biosynthesis of eumelanins.     

Synthesis of a fluorinated analog of the sex pheromone of the processionary moth thaumetopoea. pityocampa(denis and schiff.)

The synthesis of ($\text{E}$)-13-fluorohexadec-13-en-11-ynyl acetate $\text{1}$, a fluorinated analog of the sex pheromone of the processionary moth Thaumetopoea pityocampa is described. The synthetic scheme involves epoxidation of the double bond, regioselective opening of the oxirane ring with Olah's reagent, tosylation of the resulting fluorohydrin and dehydrotosylation. Structural features of the intermediate diastereomeric fluorohydrins $\text{4a}$ and $\text{4b}$ and tosylates $\text{5a}$ and $\text{5b}$ are also discussed on the basis of their ¹H and ¹⁹F NMR spectra.     

Conformational analysis of trans-2,3-diaryloxy-1,4-dioxanes. A tool for discriminating between steric and electronic effects in the position of

The conformation of several $\text{trans}$-2,3-diaryloxy-1,4-dioxanes has been studied using ¹H NMR techniques. $\text{Trans}$-2,3-bis(4-nitrophenoxy)-1,4-dioxane and $\text{trans}$-2,3-bis(4-methoxyphenoxy)-1,4-dioxane have been found to be predominantly ( ≈98%) in diaxial conformation in CDCl₃). On the other hand, $\text{trans}$-2,3-bis(2,6-dimethylphenoxy)-1,4-dioxane exists in the same conditions as a 66:33 mixture of diaxial and diequatorial conformers. An explanation based on the fulfilment of the exo-anomeric effect is provided.     

Oxidation with sodium peroxide Direct introduction of a γ carbonyl group into α,β unsaturated ketosteroids

Aqueous sodium peroxide oxidises the conjugated Δ⁴-3-ketosteroids $\text{1a}$-$\text{1d}$ to the corresponding Δ⁴-3-4-diones in good yield. Saturated carbonyl and alcohol groups are not affected by the reaction.     

The octant rule. XIV. synthesis and circular dichroism of α-exo and endo-deuteriobicyclo[3.2.1]octan-3-one and 6,6-dimethybicyclo[3.1.1]heptan-3-one

(1R,5S)-2S-Deuteriobicyclo[3.2.1]octan-3-one ($\text{1}$) and (1R,5S)-2R-Deuteriobicyclo[3.2.1]octan-3-one ($\text{2}$), prepared by diazomethane ring enlargement of (1S,4R)-2(exo)-deuteriobicyclo-[2.2.1] heptan-2-one and (1S,4R)-2(endo)-deuteriobicyclo[2.2.1]heptan-2-one respectively, both gave (?) n-π^* circular dichroism (CD) Cotton effects, Δε^max₂₉₄ = ?0.05 and Δε^max₂₉₄=?0.1, respectively, in hydrocarbon solvent. (1S,5R)-2S-Deuterio-6,6-diaethylbicyclo[3.1.1] heptan-3-one ($\text{3}$) and (1S,5R)-2R-deuterio-6,6-dimethylbicyclo[3.1.1] heptan-3-one ($\text{4}$), prepared from (-) myrtenal, both exhibited extraordinary vibrational fine structure for the n-π^* CD transitions observed in hydrocarbon solvent and oppositely?signed CEs, Δε^max₂₈₂=?0.01 and Δε^max₂₇₉=+0.01 respectively in CF₃CH₂OH solvent.     

Bis(tricarbonyliron) complexes of P-quinodimethanes: fragmentation and isomerisation under electron impact

EI mass spectra of $\text{trans}$-η⁴,η⁴-[3,6-bis(methylene)-1,4-cyclohexadiene]-bis=(tricarbonyliron) complexes $\text{1a}$, $\text{b}$ are reported. The fragmentation pathway is rationalized by assuming a rearrangement of the $\text{trans}$-bis(tricarbonyliron) complexes into the $\text{cis}$-isomers under electron impact.     

Mechanisms for reactions of halogenated compounds. Part 4.[1] activating influences of ring-nitrogen and trifluoromethyl in nucleophilic aromatic substitution

Rate constants have been measured for the reactions of ammonia with various fluorinated pyridines and diazines in aqueous dioxan at 25°. From the results the activating effects of ring-nitrogen (relative to CH) and of trifluoromethyl (relative to -H) have been determined. Ring-nitrogen activates the system at points $\text{ortho}$-, $\text{meta}$- and $\text{para}$- to the point of substitution, in the ratios $\text{ortho}$- 6.2 × 10⁴, $\text{meta}$- 8.5 × 10², and $\text{para}$- 2.3 × 10⁵. Similarly a trifluoromethyl substituent is activating by a factor of 2.4 × 10³$\text{ortho}$- and 4.5 × 10³$\text{para}$- to the point of substitution.     

Penicillin-cephalosporin conversion III. A Novel route to 3-chloromethyl-Δ3-cephems

Synthesis of 3-chloromethyl-Δ³-cephems $\text{3}$ from 4-arenesulfonylthioazetidin-2-ones $\text{1}$, derived from penicillins G and V, has been achieved by the electrolytic ene-type chlorination of $\text{1}$ in a CHC1₃-aqueous NaCl-H₂SO₄-(Pt electrodes) system and subsequent ring closure with NH₃ in DMF.     

Bridgehead nitrogen heterocycles from 2,4,6-triphenyl- pyrylium cation and thiosemicarbazide or thiocarbohydrazide

2,4,6-Triphenylpyrylium with thiosemicarbazide and thiocarbohydrazide, gives 2-pyrazolines $\text{3a}$ and $\text{3b}$ which undergo cyclization yielding pyrazolo(1,5-c]pyrimidine 5 and pyrazolo [2,3-d]-1,2,4-triazepine $\text{7}$ derivatives, respectively. Reaction of $\text{7}$ with phenacyl bromides gave 1,3-thiazolo[3,2-b]pyrazolo [2,3-d]-1,2,4-triazepin-4-iums $\text{10}$. Compound $\text{3a}$ on treatment with phenacyl bromides gave 1-(4'-aryl-thiazol-2'-yl)-2-pyrazoline derivatives $\text{6}$. Compound $\text{3b}$ reacts with acyl chlorides to give pyrazolo[1,5-c]pyrimidine derivatives $\text{14}$, and with aromatic aldehydes giving the 2-(Δ^2'1 pyrazolin-1-yl)-5-aryl-1,3,4-Δ²-thiadiazolines $\text{12}$ which were easily converted to the corresponding 2-(Δ²-pyrazolin-1-yl)-5-aryl-1,3,4-thiadiazoles $\text{13}$.     

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.     

Stereoselective 1,4-addition of dialkylaluminum benzenethiolate to vinyl oxiranes

Reactions of vinyl oxiranes and diethylaluminum benzenethiolate in benzene at room temperature proceed regio- and stereoselectively to afford mainly ($\text{Z}$)-4-phenylthio-2-buten-1-ol derivatives in good yields.