RESUMO
N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H2O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H2O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the synthesis of benzimidazole and quinazolinone derivatives. Notable features of N-formylation of amines by using N-formyl imide include operational simplicity, oxidant- and metal-free conditions, structurally diverse products, and easy applicability to gram-scale operation.
RESUMO
The Diels-Alder reaction rate constants of methyl vinyl ketone with cyclopentadiene and cyclohexadiene in the presence of a novel organotungsten catalyst, [P(2-py)(3)W(CO)(NO)(2)](2+), have been measured experimentally and modeled theoretically at several temperatures. The uncatalyzed systems were also studied for direct comparison. When 0.0022 M of catalyst is present at room temperature, the rate constants were found to be approximately 5.3 and 5300 times higher than the corresponding uncatalyzed reactions for cyclopentadiene and cyclohexadiene systems, respectively. Experimental data suggested that the catalyst reduced the activation energies by 5-10 kcal/mol. However, the preexponential factors showed reduction of more than 3 orders of magnitude upon catalysis due to the entropic effects. The energy barriers and the rate constants of the uncatalyzed systems were accurately modeled by correlated electronic structure and dual-level variational transition state theory calculation. The calculated endo selectivity is in good agreement with the observed product distribution. Theoretical calculation also suggested the catalyzed reactions proceeded in a highly asynchronous or even stepwise fashion.