1,721,092 research outputs found
Solution-phase chemistry. Properties, reactivity and selectivity modeled by implicit solvation models
No full textQuinone methides as alkylating and cross-linking agents
No full textQuinone methides (QMs) are reactive intermediates involved in a large number of chemical and biological processes such as enzyme inhibition, DNA alkylation and cross-linking. Their electrophilicity towards amines, thiols, water, amino acids and peptides has been kinetically measured in aqueous solution. The alkylation process is often thermally and photochemically reversible and the resulting adducts may act as
QM carriers
Synthesis, spectroscopic characterization and chemical reactions of stable o-QM on solid phase
No full textA novel approach towards quinone methides stabilization
has been achieved by anchoring the reactive o-QM intermediate on solid phase (RTHP). The reactivity and selectivity of supported o-QM towards N and S centered nucleophiles have been explored
Modeling Acid and Cationic Catalysis on the Reactivity of Duocarmycins
No full textSeveral catalyzed alkylation reactions of 9-methyladenine by a model [CPI, cyclopropa[c]pyrrolo-[3,2-e]indol-4(5H)-one] of duocarmycin anticancer drugs have been compared to the uncatalyzed reaction in gas phase and in water solvent bulk, using density functional theory at the B3LYP level with the 6-31+G(d,p) basis set and C-PCM solvation model. The effect on the CPI reactivity induced by water, formic and phosphoric acids (general acid catalysis), H3O+ (specific acid catalysis), sodium, and ammonium cation complexation (cationic catalysis) has been investigated
MODELING PROPERTIES AND REACTIVITY OF QUINONE METHIDES BY DFT CALCULATIONS
No full textA review on the properties and reactivity of Quinone Methides as alkylating agents modelled in silico by density functional theor
Crystal structures of 2,4,9-trimethyl-(3ar,4c,9c,9ac)-3a,4,9,9a-tetrahydrobenzo[f]isoindole-1,3-dione(endo), C15H17NO2 (1), and 2-methyl-(3ac,9ac)-3a,4,9,9a-tetrahydro-4r,9c-ethanobenzo[f]isoindole-1,3-dione(endo), C15H15NO2
No full textThe title compd. 1 is triclinic, space group P1, with a 7.198(2), b 7.965(2), c 12.707(2) Å, α 72.05(1), β 87.65(2), γ 65.18(2)° ; the title compd. 2 is orthorhombic, space group and Pbca, with a 8.156(3), b 13.177(3), c 22.742(4) Å. The chiral centers in both compds. C3a, C4, C9, C9a are either R, S, R, S or S, R, S, R (compd. 1) and either R, R, S, S or S, S, R, R (compd. 2) because of the centric space grou
A new method in radical chemistry: generation of radicals by photo-induced electron transfer and fragmentation of the radical cation
No full textA review with 160 refs. on photochemically generated radicals and their applications in organic synthesi
Characterization of Methylenepropenylidenecyclohexadiene Derivatives and Their Competing 1,6-Electrocyclic Reaction and 1,7-Hydrogen Shift at Room Temperature
No full text1,2-Dihydronaphthalene-1,4-dicarbonitrile and its 1- and 2-benzyl- derivs. open upon photoexcitation to yield methylenepropenylidenecyclohexadienes (e.g., I, X = CN). The last compds., the spectra of which have been measured by flash photolysis, undergo 1,6-electrocyclic ring closure (rate 4 s-1 for the unsubstituted deriv.) and, when possible, 1,7-hydrogen shift (rate 400 s-1 for the 1-benzyl deriv.)
Stereoselective Epoxidation of cis-3,4-Disubstituted-(CH2X)-Cyclobutenes with Dimethyldioxirane and Peroxy Acids. Experimental and Computational Evidence for a Syn-Orienting Electrostatic Effect
No full textThe epoxidation reactions of a series of cis-3,4-disubstituted-(CH2X)-cyclobutenes with dimethyldioxirane (DMD) and mClPBA have been investigated with both reagents. A remarkable syn diastereoselectivity in the formation of the epoxide has been obsd. for substrates bearing electron withdrawing substituents
Photochemical reaction of phthalimides and dicyanophthalimides with benzylic donors
No full textIrradn. of phthalimides I in the presence of benzylic donors PhCR1HX (R1 = H, Ph; X = H, SiMe3, CHPh2) proceeds via electron transfer and radical cation cleavage, resulting in benzylation at the carboximide moiety to yield 3-benzyl-3-hydroxyisoindol-1-ones. With 4,5-dicyanophthalimide and its N-Me deriv., substitution of benzyl for a cyano group is a competitive, and in some cases predominating, pathway. A rationalization is proposed on the basis of the in cage vs. out of cage radical cation cleavage
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