Catalytic Oxidative Carbonylation of Arylamines to Ureas with W(CO)6/I2 as Catalyst
作者:Li Zhang、Ampofo K. Darko、Jennifer I. Johns、Lisa McElwee-White
DOI:10.1002/ejoc.201100657
日期:2011.11
was carried out by using W(CO)6 as the catalyst, I2 as the oxidant, CO as the carbonyl source and 4-(dimethylamino)pyridine (DMAP) as base. The reaction conditions were optimized with respect to different bases, molar ratio of DMAP/iodine, temperature, time, and CO pressure. Various p-substituted arylamines can be converted into the respective symmetrical and unsymmetrical N,N′-disubstituted ureas in
Influence of Polarity on the Scalability and Reproducibility of Solvent-Free Microwave-Assisted Reactions
作者:Angel Diaz-Ortiz、Antonio de la Hoz、Jesus Alcazar、Jose R. Carrillo、Maria A. Herrero、Alberto Fontana、Juan de M. Munoz、Pilar Prieto、Abel de Cozar
DOI:10.2174/138620711794474088
日期:2011.2.1
Organic reactions performed in the absence of solvent in domestic ovens without appropriate temperature control are generally considered as not reproducible, particularly when different instruments are used. For this reason, reproducibility has historically been one of the major issues associated with Microwave-Assisted Organic Synthesis (MAOS) especially when domestic ovens are involved. The lack of reproducibility limits the general applicability and the scale up of these reactions. In this work several solvent-free reactions previously carried out in domestic ovens have been translated into a single-mode microwave reactor and then scaled up in a multimode oven. The results show that most of these reactions, although not considered as reproducible, can be easily updated and applied in microwave reactors using temperature-controlled conditions. Furthermore, computational calculations can assist to explain and/or predict whether a reaction will be reproducible or not.