Use of SPME-GC-MS in the study of time evolution of the constituents of saffron aroma: modifications of the composition during storage

The effect of storage on the composition of saffron aroma is studied. Six samples of saffron from different areas of Italy are analyzed by solid-phase microextraction-gas chromatography-mass spectrometry. Samples 1, 2, and 3 are derived from cultivations of Crocus sativus in the zone of Salerno (Southern Italy) from 2000 to 2002. Samples 4, 5, and 6 are derived from cultivations in Sardinia, Italy (from 1998, 2000, and 2001, respectively). In all samples, 3,5,5-trimethyl-2-cyclohexen-1-one; 3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-trimethyl-6-hydroxy-3-carboxaldehyde-2,5-cyclohexadien-1-one are found. 5,5-Dimethyl-2-methylene-1-carboxaldehyde-3-cyclohexene; 3,5,5-trimethyl-1,4-cyclohexandione; and beta-ionone are found with nonanal, dihydro-beta-ionone, and 2,6-di-t-butylphenol. Safranal is the main component in all of the samples. The most important changes are in the presence of alcohols and aldehydes and oxidation products of the major terpenoids components. Furthermore, the presence of safranal--the most important constituent of the flavor--changes during the time, increasing during 3 years, then decreasing after 5 years.     

Reactions of Sodium Enolates Derived from 6-Aryl-3,5,5-trimethyl-2,3,5,6-tetrahydropyrane-2,4-diones with Substituted Benzenesulfonyl Chlorides and Arenediazonium Salts

Sodium enolates derived from 6-aryl-3,5,5-trimethyl-2,3,5,6-tetrahydropyrane-2,4-diones react with substituted benzenesulfonyl chlorides to give the corresponding O-sulfonation products, 6-aryl-4-(4-R-phenylsulfonyloxy)-3,5,5-trimethyl-5,6-dihydropyrane-2-ones. Reactions of the title compounds with arenediazonium tetrafluoroborates afford 6-aryl-3-arylazo-3,5,5-trimethyl-2,3,5,6-tetrahydropyran-2,4-diones as mixtures of syn and anti isomers.     

Novel Synthesis of 3,5,5-Trimethyl-4-(2-butenylidene)-cyclohex-2-en-1-one,a Major Constituent of Burley Tobacco Flavour

The acetylenic diol 2 , prepared by reaction of but-3-yn-2-ol dianion with 2,6,6-trimethyl-4,4-ethylenedioxy-cyclohex-2-en-1-one ( 1 ), afforded 3,5,5-trimethyl-4-(2-butenylidene)-cyclohex-2-en-1-one ( 4 ), a major constituent of Burley tobacco flavour, upon LiAlH₄ reduction and hydrolysis. Vomifoliol ( 5 ) and blumenol C ( 6 ) were major by-products in this reaction.     

Reaction of ethyl 2,4-dibromo-2,4-dimethyl-3-oxopentanoate with zinc and aldehydes

Ethyl 2,4-dibromo-2,4-dimethyl-3-oxopentanoate reacts with zinc and aliphatic or aromatic aldehydes to furnish 3,5,5-trimethyl-6-R-2,3,5,6-tetrahydropyran-2,4-diones as a single geometrical isomer that in polar solvents converts into enol form.     

Preparation and nitrosation of 3,4-dimethyl-3-penten-2-one (e)- and (z)-oximes. Formation of 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide and of 2-isoxazoline derivatives

The stereoisomeric (E)- and (Z)-oximes of 3,4-dimethyl-3-penten-2-one were prepared and nitrosated with butyl nitrite in methanol. The (E)-oxime gave 3,3,4,5-tetramethyl-3H-pyrazole 1,2-dioxide in nearly quantitative yield, while the (Z)-oxime reacted less readily, giving a lower yield of the same product, with five other products identified as isoxazoline derivatives. Three of these were 4-hydroxy-, 4-methoxy-, and 4-nitro-3,4,5,5-tetramethyl-2-isoxazoline. The fourth was the O-(3,4,5,5-tetramethyl-2-isoxazolin-4-yl) derivative of the starting (Z)-oxime, and the fifth was 4-methylene-3,5,5-trimethyl-2-isoxazoline.     

The cyclodimerisation of 3-methyl-2-butenenitrile

3-Methyl-2-butenenitrile (1) cyclodimerised on treatment with lithium diisopropylamide in dimethoxyethane at temperatures between ?78°C and 0°C to 3-amino-4-cyano-1,5,5-trimethyl-1,3-cyclohexadiene (2) the structure of which was established by acid hydrolysis to the known 4-cyano-1,5,5-trimethyl-1-cyclohexene-3-one (3).     

Reactions of oxaphospholanols and phosphorous acid monochlorides

Conclusions The reaction of 2-alkoxy-2-oxo-3,5,5-trimethyl-1,2-oxa-phospholan-3-ols and monochlorides of trivalent-phosphorus acids yielded the corresponding phosphites, phosphonites, and phosphoramidites.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 683–685, March, 1970.     

Unexpected synthesis of azepino[4,3,2-cd]indoles from 4-aminoindoles

Unexpected regioselectivity for the Skraup-Doebner-Von Miller reaction was observed during the synthesis of quinolines from 4-aminoindoles and acetone in the presence of hydrochloric acid as a catalyst. The products were unambiguously assigned as 1-alkyl-3,5,5-trimethyl-5,6-dihydro-1H-azepino[4,3,2-cd]indoles instead of 2,2,4-trimethyl-2,7-dihydro-1H-pyrrolo[2,3-h]quinolones based on NMR spectroscopy and X-ray crystallographic analysis.     

Friedel-Craft acylation of ar-himachalene: synthesis of acyl-ar-himachalene and a new acyl-hydroperoxide

Friedel-Craft acylation at 100 °C of 2,5,9,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocycloheptene [ar-himachalene], a sesquiterpenic hydrocarbon obtained by catalytic dehydrogenation of α-, β- and γ-himachalenes, produces a mixture of two compounds: (3,5,5,9-tetramethyl-6,7,8,9-tetrahydro-5H-benzocyclohepten-2-yl)-ethanone (2, in 69% yield), with a conserved reactant backbone, and 3, with a different skeleton, in 21% yield. The crystal structure of 3 reveals it to be 1-(8-ethyl-8-hydroperoxy-3,5,5-trimethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-ethanone. In this compound O-H…O bonds form dimers. These hydrogen-bonds, in conjunction with weaker C-H…O interactions, form a more extended supramolecular arrangement in the crystal.     

Beckmann and cyclization reactions of δ-oxo-α,β-unsaturated ketoximes obtained from pyrylium salts and hydroxylamine. formation of 2-aryl(or alkyl)amino-4,6-disubstituted pyrylium salts

The reaction of 2,4,6-trisubstituted pyrylium salts 1 with hydroxylamine gave regio- and stereo-selectively 1,3,5-trisubstituted 2-cis-pentene-1,5-dione 1-oximes 4. On cyclization, 3,5,5-trisubstituted 2-isoxazolines 6 and 2,4,6-trisubstituted pyridine 1-oxides 5 were obtained, originating in the antilsyn stereoisomers of oxime 4, respectively. Beckmann reaction of keto-ketoximes 4 with thionyl chloride unexpectedly gave 2-aryl (or alkyl) amino-4,6-di-substituted pyrylium salts 7, the first example of rearrangement/cyclization involving carbonylic oxygen as terminator. Crystallographic data are provided for (Z)-N-t-butyl-3,6,6-trimethyl-2-heptenecarboxamide 13b.     

An improved synthesis of 3-deazaeytosine, 3-deazauracil, 3-deazacytidine,and 3-deazauridine

3-Dcazacytosine (4-amino-2-pyridone, 3 ), 3-doazauracil (4-hydroxy-2-pyridone, 5 ), 3-deaza-cytidine (4-amino-1-β-D-ribofuranosyl-2-pyridonc, 9 ), and 3-deazauridine (4-hydroxy-1-β-D-ribo-furanosyl-2-pyridone, 11 ) were prepared in high overall yields from 1-methoxy-1-buten-3-yne ( 1 ). Ethyl 3,5,5-triethoxy-3-pentenoate ( 2 ), obtained from acylatioti of 1 with diethyl carbonate and subsequent in situ conjugate addition of ethoxide, was cyelized with ammonia to provide 3 . Diazotization of 3 and subsequent in situ hydroxydediazotization afforded 5 . Nucleoside 9 was obtained from the stannic chloride-catalyzed condensation of bis-trimethylsilylated 3 and 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose ( 7 ), followed by ammonolysis of the blocking groups. Diazotization of 9 and subsequent in situ hydroxydediazotization afforded nucleosidc 11 .     

1,2,5-Trimethyl-4-aminopiperidine and 3, 6-dimethyl-4-phenyl-2-aminopyridine

1,2,5-Trimethylpiperid-4-one is used to prepare 1, 2, 5-trimethyl-4-aminopiperidine, which is then converted to 1, 2, 5-trimethyl-4-(diethylaminoacetylamino)piperidine. Amination of 2, 5-dimethyl-4-phenylpyridine is effected, and 3, 6-dimethyl-4-phenyl-2-aminopyridine is thereby obtained.     

Quantum-chemical Modeling of the Reaction of 3-Pyridinecarbaldehyde with 3-Cyano-4,5,5-trimethyl-2(5H)-furanone

The condensation of pyridinecarbaldehydes with 3-cyano-4,5,5-trimethyl-2(5H)-furanone and 3-cyano-4,6,6-trimethyl-5,6-dihydro-2(2H)-pyranone leads to the formation of the products of crotonic condensation and compounds of the Michael adduct type. A model investigation of the mechanism by the semiempirical AM1 quantum-chemical method for the case of the reaction of 3-pyridinecarbaldehyde with 3-cyano-4,5,5-trimethyl-2(5H)-furanone showed that the products can be formed in parallel from one and the same intermediate compound.     

Hybrid CO2-philic surfactants with low fluorine content

The relationships between molecular architecture, aggregation, and interfacial activity of a new class of CO(2)-philic hybrid surfactants are investigated. The new hybrid surfactant CF2/AOT4 [sodium (4H,4H,5H,5H,5H-pentafluoropentyl-3,5,5-trimethyl-1-hexyl)-2-sulfosuccinate] was synthesized, having one hydrocarbon chain and one separate fluorocarbon chain. This hybrid H-F chain structure strikes a fine balance of properties, on one hand minimizing the fluorine content, while on the other maintaining a sufficient level of CO(2)-philicity. The surfactant has been investigated by a range of techniques including high-pressure phase behavior, UV-visible spectroscopy, small-angle neutron scattering (SANS), and air-water (a/w) surface tension measurements. The results advance the understanding of structure-function relationships for generating CO(2)-philic surfactants and are therefore beneficial for expanding applications of CO(2) to realize its potential using the most economic and efficient surfactants.     

Ring-chain tautomerism of acetone N-methylated thiosemicarbazones

Ring-chain tautomerism of acetone N-methylated thiosemicarbazones was studied by nmr spectroscopy. Acetone thiosemicarbazone, acetone 2-methylthiosemicarbazone, and acetone 4-methylthiosemicarbazone exist as chain forms in DMSO-d₆ and ring forms in deuteriotrifluoroacetic acid. However, the compound obtained by reaction of acetone with 2,4-dimethylthiosemicarbazide exists only as the ring form 3,5,5-trimethyl-1,3,4-thiadiazolidine-2-methylimine both in DMSO-d₆ and in deuteriotrifluoroacetic acid, due to steric hindrance of the three methyl groups.     

相转移催化合成香料烟酮及中间体异佛尔酮

报道了香料烟酮（2-羟基-3，5，5-三甲基-2-环戊烯酮）及中间体异佛尔酮的合成，首先用4-甲基-3-戊烯-2-酮与乙酰乙酸乙酯，在相转移催化剂Et3N^ CH2PhCl^-和EtONa/EtOH条件下合成中间体异佛尔酮，异佛尔酮在碱性条件下被H2O2氧化成2,3-环氧异佛尔酮，2，3-环氧异佛尔酮在酸性条件下反应生成烟酮，对烟酮的IR，^1H NHR谱进行了分析。     

The first 1-alkyl-3-perfluoroalkyl-4,5- dimethyl-1,2,4-triazolium salts

Syntheses of quaternary 1-alkyl-3-perfluoroalkyl-4,5-dimethyl-1,2,4-triazolium iodides have led to a variety of new quaternary salts via metathesis reactions. 1,4,5-Trimethyl-3-trifluoro-methyl-1,2,4-triazolium iodide (6) with LiN(SO(2)CF(3))(2), KSO(3)CF(3), AgClO(4), AgBF(4); 1-(3-fluoropropyl)-3-trifluoromethyl-4,5-dimethyl-1,2,4-triazolium iodide (7) with LiN(SO(2)CF(3))(2); and 1,4,5-trimethyl-3-perfluorooctyl-1,2,4-triazolium iodide (8) with LiN(SO(2)CF(3))(2), AgClO(4), AgBF(4) gave excellent yields of new thermally stable and relatively low melting quaternary salts. The structure of 1,4,5-trimethyl-3-perfluorooctyl-1,2,4-triazolium tetrafluoroborate (11c) was confirmed by single-crystal X-ray analysis. Although the molecular weight of 11c (cation) is 3-fold greater than that of the 3-trifluoromethyl derivative 9d, its melting point is 32 degrees C lower.     

Synthesis of heterocyclics via enamines—IX : Reactions of 1-substituted-4,4,6-trimethyl-1,4-dihydropyrimidine-2(3h)thione derivatives with dihalocarbenes

Dichloroarbene with 1-substituted 4,4,6 trimethyl- 1,4 dihydropyrimidine 2(3H) thione derivatives (2) formed 7,7-dichloro 3 [(dichloromethyl)thio]-2-substituted-1,5,5-trimethyl-2,4-diazabicyclo[4,1.0] hept-3-ene (3) and 7,7-dichloro-2-substituted-1,5,5-trimethyl-2,4-diazabicyclo [4.1.0] heptane-3 thione (4). On heating as such or under acidic or basic conditions, 3 changed to the corresponding 4 quantitatively. Diiodocarbene with 2 (RCH₃, Ph) formed mainly the corresponding 1-substituted 4,4,6-trimethyl-1,4-dihydropyrimidine-2 one 7 (RCH₃ Ph) 7 (RCH₃).     

3-(Het)arylglutamic acid hydrochlorides: synthesis and structure

Acid hydrolysis of 4-(het)aryl-3,5,5-tris(alkoxycarbonyl)-2-pyrrolidones obtained by the condensation of 1,1-bis(alkoxycarbonyl)ethenes with diethyl acetylaminomalonate leads to (2R*,3R*)-3-(het)arylglutamic acid hydrochlorides.     

Five-membered 2,3-dioxo heterocycles: LXXVIII. Acylation of fischer’s base with aroylketenes. Crystalline and molecular structure of (1E, 3Z)-4-(4-chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-2-one

Aroylketenes generated by thermolysis of 6-aryl-2,2-dimethyl-4H-1,3-dioxin-4-ones reacted with 1,3,3-trimethyl-2-methylidene-1,3-dihydro-2H-indole (Fischer’s base) to produce (1E,3Z)-4-aryl-4-hydroxy-1-(1,3,3-trimethyl-1,3-dihydro-2H-indol-2-ylidene)but-3-en-2-ones. The crystalline and molecular structures of (1E,3Z)-4-(4-chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-2-one were determined by X-ray analysis.