Ewch i’r prif gynnwys
Dr Rebecca Melen

Dr Rebecca Melen

Lecturer in Inorganic Chemistry

Yr Ysgol Cemeg

Links

Research Groups: Inorganic Chemistry

Research Interests

Main Group chemistry has undergone a renaissance in recent years with the realisation that the reactivity of main group elements often closely resembles that of transition metals, with recent studies revealing that main group elements can act as homogenous catalysts for a range of transformations. The development of main group alternatives to conventional transition metal catalysts is an emerging $acirc; hot topic$acirc; . Previous research by Melen pioneered the use of Main-Group complexes in the catalytic dehydrocoupling of amino-boranes [1] for which she received the RSC Dalton Young Researcher Award (2013). Her subsequent studies on heterocyclic synthesis via Main Group Lewis acid promoted organic transformations [2] coupled with her dehydrocoupling studies led to her European Young Researcher Award (2014). Amongst her published research, she has several articles designated as $acirc; hot papers$acirc; and/or reflected in Front/Inside Cover artwork. Research projects in the Melen group draw together several different areas of chemistry including organic and inorganic synthesis, main group chemistry, catalysis and implement a range of physical characterisation methods (including multinuclear NMR and X-ray diffraction) supported by computational studies.

References:

[1]   Chem. Commun., 2011, 47, 2682; Chem. Sci., 2011, 2, 155; RSC Advances, 2012, 2, 2191.

[2]   Chem. Eur. J., 2013, 19, 11928; J. Am. Chem. Soc., 2014, 136, 777; Chem. Commun., 2014, 50, 1161 (inside cover); Chemical Commun., 2014, 50, 7243-7245 (Front cover).

BA and MSci (1st Class Honours), University of Cambridge (2004$acirc; 2008); PhD, University of Cambridge (2008-2012, Prof. Dominic Wright); Postdoctoral Fellow, University of Toronto, Canada (2012-2013, Prof. Douglas Stephan); Humboldt Fellow, University of Heidelberg, Germany (2013-2014, Prof. Lutz Gade). Appointed as a Lecturer in Chemistry, Cardiff (2014). Significant awards: RSC Dalton Young Researchers Award (2013); European Young Researchers$acirc; Award (2014).

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Research in the Melen group focuses on the use of main group Lewis acids in organic synthesis and catalysis. The research programme includes:

  • Main group catalyst design including tuning the steric and electronic effects of the Lewis acid.
  • Applications of main group Lewis acids in organic synthesis and catalytic processes.
  • Mechanistic studies to determine reaction pathways and the role of the Lewis acid in the reactions using combinations of experimental and theoretical methods.

Recent Progress:

The Lewis acidic nature of Main Group compounds can be tailored electronically and sterically by substituents. We have implemented the Lewis-acid nature of Main Group compounds to drive a range of important chemical transformations which have potential applications in the synthesis of pharmaceutically important organic heterocycles and/or in materials chemistry. Recent results have shown that the boron Lewis acid B(C6F5)3 could promote both stoichiometric (and catalytic) organic cyclisation processes in heterocyclic synthesis (Fig. 1). These studies established that B(C6F5)3 was capable of acting in a similar way to transition metal catalysts allowing the conversion of propargyl amides into oxazoles. Depending on the substituents R and temperature, we were able to identify almost every intermediate in the reaction pathway.

Fig. 1.

However, the main group Lewis acidic B(C6F5)3 can lead to some very different outcomes than those observed for transition metal catalysed transformations. For example, replacement of the propargyl amide by a propargyl ester leads to marked differences in reactivity. Relating to this, the reactions of B(C6F5)3 with propargyl esters yield allyl boron reagents which can undergo addition to aldehydes to afford novel aldol products in a one-pot reaction (Fig. 2).

Fig. 2.