- N-alkylated sulfamic acid derivatives as organocatalyst in multicomponent synthesis of fatty dihydropyrimidinones
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In this work, N-alkylated sulfamic acid derivatives are introduced as promising acidic organocatalysts with convenient acidity and easy synthesis. The new organocatalysts derived from different nitrogenated compounds (amines, chitosan, urea and thiourea) were applied in multicomponent reactions to synthesize several dihydropyrimidinones (DHPMs). All tested organocatalysts resulted in good DHPM yields, using classic 1,3-dicarbonyl compounds and long-chain 1,3-dicarbonyl derivatives, demonstrating catalytic efficiency. N-Alkylated sulfamic acid derived from benzylamine showed good results (ca. 80percent yields). In addition, excellent results were obtained with organocatalysts based on sulfamic acid and thiourea (ca. 80-97percent yields), demonstrating the catalytic efficiency of new derivatives of thiourea organosulfamic catalysts.
- Hack, Carolina R. L.,Porciuncula, Larissa,Weber, Andressa C. H.,D’Oca, Caroline R. M.,Russowsky, Dennis,Moura, Jaqueline M.,Pinto, Luiz A. A.,D’Oca, Marcelo G. M.
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- N-Nitrososulfamates: Sources of Carbonium Ions in Aqueous Media and Substrates in Solid-State Decompositions
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Potassium N-nitrososulfamates of benzylamine, 2-phenylethylamine, and cyclohexylamine 2a-c were synthesized and examined as sources of carbonium ions in aqueous media.The nitrososulfamates are crystalline compounds which decompose readily at low pHs (ca. 2) under conditions where the parent amines are relatively stable to nitrous acid.In water solutions they produce the corresponding alcohols, principally, along with small percentages of the corresponding esters of potassium bisulfate.The decomposition of the benzyl analogue 2b in the presence of sodium thiocyanate produced, principally, benzyl alcohol, but also benzyl thiocyanate and benzyl isothiocyanate in a ratio of 4.4/1, indicating a muted role for nucleophilicity in this carbonium ion reaction.In sulfate buffers they decompose by pseudo-first-order kinetics (rate constants are reported).In acetic acid they produce principally the corresponding acetate esters.A reaction mechanism is proposed in which the slow step involves the production of a diazohydroxide rather than a direct formation of a carbonium ion.The benzyl analogue 2b is an inhibitor of the enzyme pepsin; it also undergoes a photoelimination reaction on irradiation.The nitrososulfamates are perfectly stable when dry, but they undergo a relatively rapid solid-state decomposition (T1/2 ca. 2-5 days) when exposed to normal atmospheric humidity; surprisingly, the external appearence of the crystals does not change during the decompositions.The products are, principally, the esters of sulfuric acid and potassium bisulfate.
- White, Emil H.,Li, Min,Lu, Shanzheng
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p. 1252 - 1258
(2007/10/02)
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- Condensed diazepinones, processes for preparing them and pharmaceutical compositions containing these compounds
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New condensed diazepinones of general formula I are described STR1 wherein B represents one of the divalent groups STR2 and X1, X2, A, R1 to R10 and Z are defined as in the specification.
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