Research within the Davies group is concerned with investigations into a wide variety of topics including the development of new synthetic methodology, catalysis, mechanistic investigations, total synthesis and collaborative projects in medicinal chemistry. For example, this includes new applications for the conjugate addition of enantiopure lithium amides, development of kinetic resolution processes for the preparation of functionalised molecular building blocks, new methods for nucleophilic fluorination, methodology for the chemoselective functionalisation of unsaturated amines at the olefin (rather than the nitrogen atom), and application of these methodologies to the total synthesis of natural products of biological significance (including pyrrolidines, piperidines, tropanes, pyrrolizidines, and imino- and aminosugars).
(i) Lithium Amide Conjugate Addition
Chiral lithium amides have been extensively used and studied within organic synthesis as effective reagents for a range of transformations including enantioselective reduction, alkylation, deprotonation, desymmetrisation and kinetic resolution. Lithium amides may also act as nucleophiles. Within this arena, we have shown that the conjugate addition of a range of secondary lithium amides, derived from enantiopure α-methylbenzylamine, to α,β-unsaturated esters represents an efficient method for the preparation of β-amino esters and their derivatives (including β-amino acids and various alkaloids). We have exploited this reaction in a range of synthetic applications, including the initiation of tandem processes, enantiorecognition phenomena, and total synthesis.
(ii) Ammonium Directed Oxidation of Allylic Amines
Treatment of allylic amines with acid followed by m-CPBA gives the corresponding amino diols as the major products, consistent with hydrogen-bond directed attack of the peracid to give the corresponding epoxide, followed by regioselective ring-opening. This metal free sequence of reactions leads to very highly diastereoselective transformations in both cyclic and acyclic systems. We have used this methodology as the key synthetic step to enable the asymmetric syntheses of iminosugars such as (+)-1-deoxynojirimycin and aminosugars such as L-acosamine.
(iii) Ring-closing iodoamination
Treatment of a range of unsaturated amines with iodine promotes ring-closing iodoamination with concomitant N-debenzylation, providing an efficient and stereoselective route to azacycles such as pyrrolidines, pyrrolizidines and tropanes. This methodology has been used in a series of natural product syntheses including (‒)-7a-epi-hyacinthacine A1, (+)-pseudococaine and (‒)-codonopsinine.
We have utilised the methodology developed in the group in total syntheses of a range of enantiopure compounds including natural products, their analogues and other potential therapeutic agents. Recently completed syntheses include (+)-pseudococaine, (−)-absouline, (−)-angustueine, (+)-pseudodistomin D, (+)-1-deoxynojirimycin, (−)-nakinadine D, (−)-codonopsinine and (−)-hopromalinol.
There is huge potential for chemistry to have an enormous impact on the biological and medicinal world. We have several highly successful multidisciplinary research collaborations including the development of small molecules to determine stem cell fate, novel protein tyrosine phosphatase inhibitors for treatment of cancer and transcriptional upregulation of utrophin in the treatment of Duchenne Muscular Dystrophy (DMD).