1117-96-0Relevant articles and documents
Diazonium ion chemistry: Replacement of H by alkyl at the central carbon accelerates an SN2 substitution reaction
Agnew, Tara E.,Kim, Hyun-Joong,Fishbein, James C.
, p. 483 - 488 (2004)
The rate constants for hydrolysis of diazomethane, diazoethane and 1-diazopropane in aqueous 5% acetonitrile at 25°C and ionic strength 1 M (NaClO4) were measured by stopped-flow spectrophotometry. The pH-rate profile for diazomethane hydrolysis exhibits a pH-independent section in the lower pH range, 8-10, with a downward break at higher pH, as has been reported for slightly different reaction conditions. In the case of diazoethane and 1-diazopropane, the reaction remains pH independent up to pH > 13. General acid catalysis of the hydrolysis reactions of diazomethane and diazoethane were examined in the pH-independent regions. For a limited number of catalysts, the value of Bronsted α was 0.58 for both diazoalkanes. The downward break in the pH rate profile for diazomethane hydrolysis is consistent with what was previously concluded, rate-limiting protonation by H2O in the pH-independent region changing to rate-limiting attack of water on the diazonium ion in the pH-dependent region, the decrease in rate constant with increasing pH being attributed to deprotonation of the diazonium ion by hydroxide ion. The lack of a downward break in the pH-rate profiles for hydrolysis of the diazoethane and 1-diazopropane is attributed specifically to the increase, relative to the methyldiazonium ion, in the rate constant for water attack on the ethyl- and 1-propyldiazonium ions, perhaps by as much as >10 3-fold. Copyright
Terpenic Acids by Cyclopentane Annulation of Exocyclic Dienes. Synthesis of Triquinane Portion of Retigeranic Acid
Hudlicky, Tomas,Short, Robert P.
, p. 1522 - 1527 (1982)
Tricyclic ester 5 has been prepared in 13 steps from (+)-pulegone.The key step in the synthesis of 5 involved the condensation of keto ester 15 with ethyl bromocrotonate under Reformatsky conditions to yield lactone 16 as one diastereomer.Either lithium diisopropylamine or 1,8-diazabicycloundec-7-ene was used to effect the elimination to the dienic acid 17, obtained as a mixture of diastereomers in an 80:20 ratio.Conditions were developed for the cyclopropanation of 18 in good isolated yields.The pyrolysis of 19 gave tricyclic ketone 20 in 50 percent yield.The 13C NMR data are provided for all relevant intermediates.The deoxygenation of this ketone provided ester 5.The structural and stereochemical assignments are based on data amassed previously on appropriate model compounds.Potential use of 5 in a convergent synthesis of retigeranic acid (3) is indicated.The concept of generality of this method in the context of total synthesis of other naturally occuring cyclopentene carboxylates is introduced.
General Method of Synthesis of Cyclopentanoid Terpenic Acids. Stereocontrolled Total Syntheses of (+/-)Isocomenic Acid and (+/-)-Epiisocomenic Acid
Short, Robert P.,Revol, Jean-Marc,Ranu, B. C.,Hudlicky, Tomas
, p. 4453 - 4461 (1983)
(4β,8α)-1α,2,4β-Trimethyl-9α-carboxytricyclo4,8>undec-2-ene (1, isocomenic acid) and (4β,8α)-1α,2,4β-trimethyl-9β-carboxytricyclo4,8>undec-2-ene (28, epiisocomenic acid) were prepared in 10 steps from ester 13.The internal cyclopropanation of exocyclic acrylates and the subsequent vinylcyclopropane-cyclopentene rearrangement were used in an efficient synthesis of a key intermediate, triquinane 23, containing all of the contiguous quarternary centers.The utilization of abnormal Reformatsky reaction of 4-bromocrotonates with keto esters served in the preparation of important precursors to the cyclopentene annulation sequence, the lactone 15, and the dienic acid 19.Hydrogenation of 23 produced the keto ester 25a, which was converted in three steps to either 1 or 28 with complete control of stereochemistry.Carbon-13 data are reported for all intermediates.A total of eight natural products are accessible in a stereocontrolled fashion from keto ester 25a.The generality of this method is thus addressed in the context of system-oriented design of synthesis of cyclopentanoid terpenes.
Photochemistry of matrix-isolated diazoethane and methyldiazirine: Ethylidene trapping?
Seburg, Randal A.,McMahon, Robert J.
, p. 7183 - 7189 (1992)
Photolysis of matrix-isolated diazoethane (1a) at 8 K produces mainly ethene (4a), along with a small amount of 3-methyldiazirine (2a). ESR experiments employing a variety of irradiation conditions matrix media (Ar, N2, Xe) show that triplet ethylidene (3T) is not an observable photoproduct. Similar experiments fail to reveal direct evidence for either singlet or triplet ethylidene by IR or UV-vis spectroscopy. Photolysis of nascent 3-methyldiazirine (2a) also fails to yield ethylidene. Deuterium substitution produces no detectable change in the chemistry. In carbon monoxide-doped matrices, photolysis of 1 generates 3-methyldiazirine (2) and ethene (4) as well as a small amount of methylketene (5). The most plausible interpretation of these results postulates that (i) trapping of incipient singlet ethylidene (3S) by CO competes with the facile hydrogen migration and (ii) intersystem crossing to the triplet does not compete with hydrogen migration.
3H-labelled alkyl-nucleotides, -nucleosides and -bases for the immunoanalytical quantification of DNA damage and repair
Drosdziok, Wolfgang,Lutze, Catrin,Krueger, Kai,Gluesenkamp, Karl-Heinz,Rajewsky, Manfred F.
, p. 815 - 835 (2003)
Analysis of the formation and repair of structurally modified DNA is of particular interest in the study of carcinogenesis, cancer therapy and aging. The quantification of specific DNA lesions by sensitive immunoanalytical methods requires radiotracers with high specific activity. We describe the synthesis of 3H-labelled adenine-, cytosine-, guanine- and thymine-alkyl derivatives by nucleophilic N- and O-alkylation using alkyl halides and diazoalkanes: 3-alkyl[8-3H]adenine (Alkyl = Me, Et, n-Bu); O6 -alkyl-deoxy[1′,2′-3 H]guanosine (Alkyl = Me, Et, i-Pro, n-Bu); O6-ethyl-deoxyguanosine-5′ -triphosphate ([2-3H-Ethyl]; [8-3H]); O6 -alkyl-9-hydroxyhexyl-[8-3H guanine (Alkyl=Me, Et); 7-ethyl-[8,5′-3H]guanosine-3′,5′-cyclic-phosphate; O2 -and O4-alkyl-[methyl, 1′,2′-3 H]thymidine (Alkyl = Me, Et); the conversion of 3H-labelled thymidine to the corresponding 5-methylcytidine; the synthesis of three different 8-oxoguanine tracers; and the generation of thymidine glycol (5,6-dihydroxy-5,6-dihydro-[methyl-3H]thymidine) from thymidine. All radiotracers were sucessfully employed in competitive radioimmunoassays for the quantification of defined DNA alkylation products in DNA repair analyses. Copyright
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Frey
, p. 2293,2295 (1962)
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Novel transformation of ethyl cyano(dinitro)acetate in the reactions with diazomethane and diazoethane
Tyrkov,Yurtaeva
, p. 902 - 903 (2014/08/18)
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