Packed bed reactors can be used as an interesting alternative on the bioreduction of β-ketoesteres mediated by immobilized microorganisms. Here in, we report our results on the bioreduction of ethyl 3-oxohexanoate by immobilized Kluyveromyces marxianus cells and tert-butyl 3-oxobutanoate by immobilized Rhodotorula rubra cells under continuous flow conditions leading the desired β-hydroxy esters corresponding in high yields and enantiomeric excess.

A reação de esterificação catalisada por lípases foi investigada através da utilização de irradiação de microondas e aquecimento convencional com a finalidade de avaliar a presença de efeitos não térmicos de microondas na síntese de biodisel. Todas as reações foram conduzidas em equipamentos dedicados a síntese orgânica como Monowave 300 e CEM Discover, a 40 ºC e com controle interno da temperatura reacional através do uso de sondas de fibra ótica. Os experimentos sob aquecimento convencional foram realizados em reator automatizado EasyMaxTM (Mettler-Toledo) que também permite o controle da temperatura interna do meio reacional. Os resultados obtidos mostram que não há diferença entre a reação conduzida sob irradiação de microondas e aquecimento convencional, diferentemente do apontado em alguns relatos da literatura.

The esterification reaction mediated by lipases was investigated applying both microwave irradiation and conventional heating in order to evaluate the existence of nonthermal microwave effects on the biodiesel synthesis. All transformations were conducted at 40ºC in both Monowave 300 and CEM Discover instruments that allowed accurate internal reaction temperature measurements with use of fiber-optic probes. The conventional heating experiment was performed in an EasyMaxTM reactor (Mettler-Toledo), which also allowed accurate measurement of the internal temperature. The results revealed no difference on the reaction time or yield, differently than indicated by some results in the literature.

The Prins cyclization reaction has significantly advanced in the last years as demonstrated by a number of applications described in the literature. The objective of this report is to introduce this powerful synthetic methodology to the undergraduate and graduated student, since it is rarely presented in an organic synthesis formal course. This reaction is, in some cases, the methodology of choice for the preparation of natural products or drugs that present the tetrahydropyrane moiety in their structures. In this report we show some aspects of this reaction, including mechanism, scope and limitations.