Saturated heterocycles. 242. Synthesis of 2-substituted-6-(6′,7′-dimethoxy-3′,4′-dihydro-1′-isoquinolyl)-5,6,7,8-tetrahydro- quinazolin-4(3H)-one Derivatives

In the reactions of the recently synthesized β-ketoesters 1-[(3′-methoxycarbonyl- and 1-[(3′-ethoxycarbonyl-4′-oxo)-1′-cyclohexyl]-3,4-dihydroisoquinoline 4, 5 with amidines or cyclic guanidines, a number of 2-substituted-6-(6′,7′-dimethoxy-3′,4′-dihydro-1′-isoquinolyl)-5,6,7,8-tetrahydroquinazolin-4(3H)-one derivatives 6–8 were prepared. The new compounds possess various pharmacological actions.     

Synthese und Chiralität von (5R, 6R)-5,6-Dihydro-β, ψ-carotin-5,6-diol, (5R, 6R, 6′R)-5,6-Dihydro-β, ε-carotin-5,6-diol, (5S, 6R)-5,6-Epoxy-5,6-dihydro-β, ψ-carotin und (5S, 6R, 6′R)-5,6-Epoxy-5,6-dihydro-β,ε-carotin

Synthesis and Chirality of (5R, 6R)-5,6-Dihydro-β, ψ-carotene-5,6-diol, (5R, 6R, 6′R)-5,6-Dihydro-β, ε-carotene-5,6-diol, (5S, 6R)-5,6-Epoxy-5,6-dihydro-β,ψ-carotene and (5S, 6R, 6′R)-5,6-Epoxy-5,6-dihydro-β,ε-carotene Wittig-condensation of optically active azafrinal ( 1 ) with the phosphoranes 3 and 6 derived from all-(E)-ψ-ionol ( 2 ) and (+)-(R)-α-ionol ( 5 ) leads to the crystalline and optically active carotenoid diols 4 and 7 , respectively. The latter behave much more like carotene hydrocarbons despite the presence of two hydroxylfunctions. Conversion to the optically active epoxides 8 and 9 , respectively, is smoothly achieved by reaction with the sulfurane reagent of Martin [3]. These syntheses establish the absolute configurations of the title compounds since that of azafrin is known [2].     

Mass spectra of some 1-(6′-substituted-4′-methyl-2′-quinolyl)-3-methylpyrazol-5-ols and their 4-substituted analogues

Electron impact induced fragmentation of some 1-(6′-substituted-4′-metbyI-2′-quinolyI)-3-methylpyrazoI-5-ols follows a route where the pyrazole moiety is preferentially cleaved with successive losses of two moieties of 41 u. High-resolution measurements have established that the first loss is due to the ?₂HO moiety, which necessitates an intramolecular hydrogen transfer followed by ring fission. The resultant ion loses CH₃CN in a subsequent step. The origin of many fragment ions was traced with the use of B/E linked-scan spectra.     

Synthesis of 2-(o-chloropheny)- and 2-(2′,6′-dichlorophenyl)-4-formyl-1,2,3-triazoles

Mesoaldehyde 1,3-dioxime was treated with either o-chlorophenyl- or 2,6 dichloro-phenylhydrazine to give the corresponding 2-chlorophenylhydrazone. Hydrazones 1a and 1b were treated with acetic anhydride and cyclized to triazoles ( 3a and 6a ) with cesium carbonate. These were then hydrolized to the previously unknown chlorophenyltriazole aldehydes ( 4a and 4b ). They were also converted to a number of acid derivatives, alcohols, and amines.     

Stereoselective total synthesis of (+)-strictifolione and (6R)-6[(E,4R,6R)-4,6-dihydro-10-phenyl-1-decenyl)-5,6-dihydro-2H-2-pyrone

The stereoselective total synthesis of two naturally occurring α-pyrone derivatives, (+)-strictifolione and (6R)-6[(E,4R,6R)-4,6-dihydroxy-10-phenyl-1-decanyl]-5,6-dihydro-2H-2-pyrone has been accomplished involving the Sharpless kinetic resolution and olefin cross-metathesis as the key reactions.     

The conformation of t-butyl 2-methoxy-5, 6-dihydro-2 H-pyran-6-carboxylates and 6,6′- disubstituted 2-methoxy-5,6-dihydro-2H-pyran derivatives on the basis of 1H and 13 C NMR spectra

The ¹H and ¹³C NMR spectra of trans- and cis-tert-butyl 2-methoxy-5,6-dihydro-2H-pyran-6-carboxylates (1 and 2) and 6,6′-disubstituted 2-methoxy-5,6-dihydro-2H-pyrans (3-7) have been recorded. HH and CH coupling constants are discussed in terms of the ¹H₆?⁶H₁ conformational equilibrium. It has been found that 1 occurs exclusively in the ¹H₆ conformation, whereas its cis isomer, 2, exists in an equilibrium of both half-chair forms. 6,6′-Disubstituted 2-methoxy-5,6-dihydro-2H-pyrans 3-6 display spectral and conformational behaviour similar to that of 1, whereas 7 resembles 2 in this respect.     

Synthesis and 1H-NMR spectra of halogenated spiro[isobenzofuran-1(3H),9′(9H)-6′-(methylcyclohexylamino)-3′-methyl-2′-anilinoxanthene]-3-ones

Reaction of spiro[isobenzofuran-1(3H).9′(9H)-6′-(methylcyclohexylamino)-3′-methyl-2′-anilinoxanthene]-3-one ( 1 ), which is typical leuco fluoran dye, with N-bromosuccinimide and N-chlorosuccinimide leads to halogenated derivatives 2a–2c and 3 , respectively. Their structures were established by two-dimensional proton-proton (COSY) experiment and their thermal properties examined by means of DSC and compared with commercially available 1 .     

Synthesis of novel 3-carboethoxy-6-methyl-4-oxo-4H-pyrimido[1′,2′:5,6]-[1,3,5]triazino[1,2-a]benzimidazoles

Reaction of 4-amino-2-methylbenzimidazo[1,2-a][1,3,5]triazines 2 with diethyl ethoxymethylenemalonate afforded 3-carboethoxy-6-methyl-4-oxo-4H-pyrimido[1′,2′:5,6][1,3,5]triazino[1,2-a]benzimidazoles 3 , a new ring system.     

Synthesis and Infrared Absorption Spectra of 5′-methyl-2′-hydroxychalcones: I. 5′-methyl-2′-hydroxychalcone and its 4-Substituted Derivatives

Seven 2′-hydroxychalcone derivatives with a methyl group on the 5′-position were synthesized. Infrared absorption spectra of these new compounds are discussed.     

Nitration of 4-methyl-5,6-dihydro-2H-pyran and some aspects of the preparation and isomerization of nitrodihydropyrans

The reaction of 4-methyl-5,6-dihydro-2H-pyran with acetyl nitrate to give additive and substitutive nitration products has been examined. It is shown that the addition product, 4-acetoxy-4-methyl-3-nitro-tetrahydropyran, is deacylated on treatment with bases to give an ,-unsaturated nitro-compound which isomerizes under the reaction conditions to a ,-unsaturated nitro-compound. 4-Acetoxy-4-nitromethyltetrahydropyran behaves similarly.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 305–308, March, 1987.     

Separation of (3R, 3′ R)-, (3R, 3′ S; meso)-, (3S, 3′ S)- Zeaxanthin, (3R, 3′ R, 6′ R)-, (3R, 3′ S, 6′ S)- and (3S, 3′ S, 6′ S)-Lutein via the dicarbamates of (S)-(+)-α-(1-naphthyl) ethyl isocyanate

A method is described for the qualitative and quantitative determination of configurational isomers of zeaxanthin (=3,3′ -dihydroxy-β, β -carotene) and lutein (=3,3′ -dihydroxy-α -cartotene). It is based on the reaction of these zeaxathin and lutein isomers with (S)-(+)-α-(1-naphthyl) ethyl isocyanate to afford diastereomeric dicarbamates, which are analyzed by HPLC.     

C45- and C50-Carotenoids Part7 Total synthesis of (all-E,2R,6R,2′R,6′R)- and (all-E,2R,6S,2′R,6′S)-2,2′-Bis(4-hydroxy-3-methylbut-2-enyl)-γ,γ-carotene (sarcinaxanthin)

The synthesis of sarcinaxanthin ((2R,6R,2′R,6′R)- 1 ), a symmetrical C₅₀-carotenoid with two γ-end groups, isolated from Sarcina lutea and from Cellulomonas biazotea as major pigment, was based on the strategy C₂₀ + C₁₀ + C₂₀ = C₅₀ using camphoric acid as starting material for the C₂₀-end group 3. The key step of the synthesis is a ring enlargement of the cyclopentane derivative 10 with 2,4,4,6-tetrabromocyclohexa-2,5-dien-1-one (TBCO) to give the cyclohexane derivative 11 (Scheme 1). The spectroscopic data of the synthetic compound are in full agreement with the data of the isolated product and give the final proof for the (2R,6R,2′R,6′R) chirality of natural sarcinaxanthin.     

5-(α-Fluorovinyl)tryptamines and 5-(α-Fluorovinyl)-3-(N-methyl-1′,2′,5′,6′,-tetrahydropyridin-3′- and -4′-yl)indoles—5-(α-Fluorovinyl)tryptamines

5-(α-Fluorovinyl)tryptamines 4a, 4b and 5-(α-fluorovinyl)-3-(N-methyl-1′,2′,5′,6′-tetrahydropyridin-3′- and -4′-yl) indoles 5a, 5b were synthesized using 5-(α-fluorovinyl)indole ( 7 ). The target compounds are bioisosteres of 5-carboxyamido substituted tryptamines and their tetrahydropyridyl analogs.     

Concise total syntheses of (+)-strictifolione and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one

Concise and efficient asymmetric total syntheses of (+)-strictifolione 1 and (6R)-6-[(4R,6R)-4,6-dihydroxy-10-phenyldec-1-enyl]-5,6-dihydro-2H-pyran-2-one 2 have been achieved based on the strategic application of one-pot double allylboration and ring-closing metathesis reactions. The total syntheses proceeded in only five and seven steps, respectively, from readily available 3-butenal and represent the shortest syntheses of 1 and 2 reported to date.     

Synthesis and Infrared Absorption Spectra of α-methyl-2′-hydroxy-chalcones: I. α-methyl-2′-hydroxychalcone and its 4-Substituted Derivatives

Six 2′-hydroxychalcone derivatives with a methyl group on the α-position were synthesized. Infrared absorption spectra of these new compounds are discussed taking their corresponding α-hydrogen chalcoes which were also synthesized for comparison. This latter study is also utilized as a proof for the structures of these compounds of a new series.     

Mass spectra of some 2-(4′-butyl-3,′5′-dimethylpyrazol-1′-yl)-6-substituted benzothiazoles

The fragmentation of the title compounds on electron impact has been studied and the major processes interpreted. The base peak invariably appears at [M ? 43]⁺ whose origin from the butyl chain has been traced with the help of metastable ion studies and accurate mass measurements. Loss of methyl cyanide, involving the decomposition of the pyrazole moiety, is observed only from the fragment ions.     

Synthesis and spectroscopic properties of 4-(4-carboxyphenyl)-3,3′,5′-trimethyl-2,2′-pyrromethen-1,1′-BF2 complex and its methyl ester

A new, strongly absorbing red dipyrrole chromophore 1 suitable for exciton coupling studies has been synthesized and shown to exhibit an intense absorption (?? 57,000) at λ (max) ?520 nm and a strong fluorescence at λ (em) ?555 nm.