Showing papers by "Carlos A. M. Afonso published in 2001"
TL;DR: The Baylis-Hillman reaction using 1,4-diazabicyclo[2.2] octane (DABCO) has been shown to be 33.6 times faster in the recyclable ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) than in acetonitrile as discussed by the authors.
117 citations
TL;DR: Non-porous membranes with the selective layer consisting of hydrophilic or hydrophobic polymers have been applied for the quantitative and selective recovery of solutes with different physico-chemical properties from a room-temperature ionic liquid, ([bmim][PF6]).
104 citations
TL;DR: A comparative study of tetrahydropyranylation of 1-phenylethanol by TsOH, pyridinium p-toluenesulphonate (PPTS) and triphenylphosphine hydrobromide (TPP) was conducted in this article.
53 citations
TL;DR: Different enzyme loading procedures were studied in the biphasic reactor and the resulting axial and radial enzyme distribution in the hollow fibre module were related to the global enzymatic activity.
33 citations
TL;DR: In this article, the reaction of endocyclic enecarbamates to form functionalized 3-aminopyrrolidines and piperidines is described, and the formation and trapping of the N-acyliminium ions derived from these substrates under Lewis acidic conditions is also explored for the stereoselective preparation of 2-alkyl pyrrolidine derivatives.
21 citations
TL;DR: In this paper, a new model for rationalisation of previously reported DKR results is presented, based both on experimental and molecular modelling results which indicate that selectivity arises from the interaction between the leaving group and the stereodifferentiating substituent of the chiral auxiliary.
19 citations
8 citations
TL;DR: New types of oligomeric organophosphorus compounds, formed by a novel 1,4-addition type ring opening polymerisation, were identified as the stable intermediates of the imide-amide rearrangement, which upon heating yield the previously reported rearranged product.
Abstract: Studies aimed at the development of new synthetic pathways for the preparation of chiral cyclic oxaza and diaza phosphoramides suitable for use in asymmetric chemistry led us to the investigation of the imide -amide rearrangement of cyclic phosphorimidates. As a result of this work new types of oligomeric organophosphorus compounds, formed by a novel 1,4-addition type ring opening polymerisation, were identified. These compounds are the stable intermediates of the imide-amide rearrangement, which upon heating yield the previously reported rearranged product. A detailed study of the mechanism of the Lewis acid catalysed imide-amide rearrangement and stereochemical control of the final products is reported. As a result, the full mechanism was elucidated and evidence of retention of configuration at the rearranged carbon atom is presented. Substituent effects were rationalised based on molecular modelling calculations.
7 citations
TL;DR: Optimised conditions for the acylation of (S)-4-(1-methylethyl) -oxazolidin-2-one 4, (R)-4-phenyloxazolisin-1-one 5 and 4-(R), (5S)-1,5-dimethyl-4 -phenylimidazolidins-2 -one 3 with 2-bromoacyl halides were developed.
5 citations