Stereoselective synthesis of enantiomerically pure cis-2,5-disubstituted-2,5-dihydropyrrole system from glycals

Multisubstituted 2,5-dihydropyrroles are recognized as valuable heterocycles systems because they could be advantageously used as starting materials for the preparation of many pharmaceutically relevant compounds. The possibility of the construction of an enantiomerically pure cis-2,5-disubstituted-2,5-dihydropyrrole system starting from D-allal and D-galactal-derived vinyl N-mesyl aziridines, when subjected to appropriate reaction conditions, was examined. The reaction of N-mesyl aziridines with metal enolates derived from active methylene compounds, as dimethyl malonate and dibenzoyl methane, afforded, through a rearrangement process implying an opening-closing process with contemporary ring contraction of the initially obtained 1,4-addition product (primary reaction product), the corresponding cis-2,5-disubstituted-2,5-dihydropyrrole (the secondary reaction product) in a completely regio- and stereoselective fashion. Subsequently, the possibility of substituting the N-mesyl group of aziridine with an easily removable protecting-activating-group was checked in the same rearrangement process. In this framework N-nosyl group turned out to be sufficiently efficient for the rearrangement process to 2,5-dihydropyrroles and easy to be removed by the simple PhSH/K2CO3 protocol to give corresponding 2,5-dihydropyrroles bearing the free NH group. Preliminary studies were also carried out on the new N-Cbz and N-TFA substituted aziridines in order to check the possibility of using these alternative N-protections in glycosylation reactions of alcohols taken as a simple and appropriate model reaction

Isothiourea-catalysed enantioselective pyrrolizine synthesis : synthetic and computational studies

We thank Syngenta and the EPSRC (grant code EP/K503162/1) (DGS), and the EPSRC Centre for Doctoral Training in Critical Resource Catalysis (CRITICAT, grant code EP/L016419/1) (ERG,SFM, RWFK) for funding. The European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013) ERC Grant Agreement No. 279850 is also acknowledged (JET). ADS thanks the Royal Society for a Wolfson Research Merit Award.The catalytic enantioselective synthesis of a range of cis-pyrrolizine carboxylate derivatives with outstanding stereocontrol (14 examples,>95:5 dr, >98:2 er) through an isothiourea-catalyzed intramolecular Michael addition-lactonisation and ring opening approach from the corresponding enone acid is reported. An optimised and straightforward three-step synthetic route to the enone acid starting materials from readily available pyrrole-2-carboxaldehydes is delineated, with benzotetramisole (5 mol%) proving the optimal catalyst for the enantioselective process. Ring-opening of the pyrrolizine dihydropyranone products with either MeOH or a range of amines leads to the desired products in excellent yield and enantioselectivity. Computation has been used to probe the factors leading to high stereocontrol, with the formation of the observed cis-steroisomer predicted to be kinetically and thermodynamically favoured.Publisher PDFPeer reviewe

Synthesis of the natural product descurainolide and cyclic peptides from lignin-derived aromatics

The authors acknowledge the EPSRC UK National Mass Spectrometry Facility at Swansea University for mass spectrometry analysis. Financial support from: the Engineering and Physical Sciences Research Council (grant EP/J018139/1, EP/K00445X/1 (NJW, ADS, OSO), the doctoral training grant (ARN) and the CRITICAT Centre for Doctoral Training [Ph.D. studentship to SFM; Grant code: EP/L016419/1]), the Leverhulme Trust (JET), European Research Council (ERC-2013-ADG (JHN))Alternative sources of potential feedstock chemicals are of increasing importance as the availability of oil decreases. The biopolymer lignin is viewed as a source of useful mono-aromatic compounds as exemplified by the industrial scale production of vanillin from this biomass. Alternative lignin-derived aromatics are available in pure form but to date examples of the use of these types of compounds are rare. Here we address this issue by reporting the conversion of an aromatic keto-alcohol to the anti- and syn-isomers of Descurainolide A. The key step involves a rhodium-catalyzed allylic substitution reaction. Enantioenriched allylic alcohols were generated via an isothiourea-catalyzed kinetic resolution enabling access to both the (2R,3R) and (2S,3S) enantiomers of anti-Descurainolide A. In addition we show that the ligninderived keto-alcohols can be converted into unnatural amino acid derivatives of tyrosine. Finally, these amino acids were incorporated into cyclic peptide scaffolds through the use of both chemical and an enzyme-mediated macrocylisation.PostprintPeer reviewe

The Changing Landscape of Neonatal Diabetes Mellitus in Italy Between 2003 and 2022

Context In the last decade the Sanger method of DNA sequencing has been replaced by next-generation sequencing (NGS). NGS is valuable in conditions characterized by high genetic heterogeneity such as neonatal diabetes mellitus (NDM).Objective To compare results of genetic analysis of patients with NDM and congenital severe insulin resistance (c.SIR) identified in Italy in 2003-2012 (Sanger) vs 2013-2022 (NGS).Methods We reviewed clinical and genetic records of 104 cases with diabetes onset before 6 months of age (NDM + c.SIR) of the Italian dataset.Results Fifty-five patients (50 NDM + 5 c.SIR) were identified during 2003-2012 and 49 (46 NDM + 3 c.SIR) in 2013-2022. Twenty-year incidence was 1:103 340 (NDM) and 1:1 240 082 (c.SIR) live births. Frequent NDM/c.SIR genetic defects (KCNJ11, INS, ABCC8, 6q24, INSR) were detected in 41 and 34 probands during 2003-2012 and 2013-2022, respectively. We identified a pathogenic variant in rare genes in a single proband (GATA4) (1/42 or 2.4%) during 2003-2012 and in 8 infants (RFX6, PDX1, GATA6, HNF1B, FOXP3, IL2RA, LRBA, BSCL2) during 2013-2022 (8/42 or 19%, P = .034 vs 2003-2012). Notably, among rare genes 5 were recessive. Swift and accurate genetic diagnosis led to appropriate treatment: patients with autoimmune NDM (FOXP3, IL2RA, LRBA) were subjected to bone marrow transplant; patients with pancreas agenesis/hypoplasia (RFX6, PDX1) were supplemented with pancreatic enzymes, and the individual with lipodystrophy caused by BSCL2 was started on metreleptin.Conclusion NGS substantially improved diagnosis and precision therapy of monogenic forms of neonatal diabetes and c.SIR in Italy

The Silent Epidemic of Diabetic Ketoacidosis at Diagnosis of Type 1 Diabetes in Children and Adolescents in Italy During the COVID-19 Pandemic in 2020

To compare the frequency of diabetic ketoacidosis (DKA) at diagnosis of type 1 diabetes in Italy during the COVID-19 pandemic in 2020 with the frequency of DKA during 2017-2019

Isothiourea-Catalysed Acylative Kinetic Resolution of Aryl-Alkenyl (sp2 vs sp2) Substituted Secondary Alcohols

aryl-alkenyl (sp2 vs sp2) substituted secondary alcohols is described, with effective enantiodiscrimination achieved using the isothiourea organocatalyst HyperBTM (1 mol%) and isobutyric anhydride. The kinetic resolution of a wide range of aryl-alkenyl substituted alcohols has been evaluated, with either electron-rich or naphthyl aryl substituents in combination with an unsubstituted vinyl substituent providing the highest selectivity (S = 2-1980). The demonstration of this protocol for the gram-scale (2.5 g) kinetic resolution of a model aryl-vinyl (sp2 vs sp2) substituted secondary alcohol is demonstrated, giving access to >1 g of each of the product enantiomers both in 99:1 er

Data underpinning - Catalytic Enantioselective Synthesis of Pyrrolizine Carboxylates using Isothiourea Catalysis: A Synthetic and Computational Study

Data set for synthetic experimental wor

Synthesis of the natural product descurainolide and cyclic peptides from lignin-derived aromatics

Alternative sources of potential feedstock chemicals are of increasing importance as the availability of oil decreases. The biopolymer lignin is viewed as a source of useful mono-aromatic compounds as exemplified by the industrial scale production of vanillin from this biomass. Alternative lignin-derived aromatics are available in pure form but to date examples of the use of these types of compounds are rare. Here we address this issue by reporting the conversion of an aromatic keto-alcohol to the anti- and syn-isomers of Descurainolide A. The key step involves a rhodium-catalyzed allylic substitution reaction. Enantioenriched allylic alcohols were generated via an isothiourea-catalyzed kinetic resolution enabling access to both the (2R,3R) and (2S,3S) enantiomers of anti-Descurainolide A. In addition we show that the ligninderived keto-alcohols can be converted into unnatural amino acid derivatives of tyrosine. Finally, these amino acids were incorporated into cyclic peptide scaffolds through the use of both chemical and an enzyme-mediated macrocylisation