Christopher Hulme

Novel applications of ethyl glyoxalate with the Ugi MCR

Abstract This letter describes novel high-yielding solution phase preparations of 1,4-benzodiazepine-2,5-dione, diketo-piperazine, ketopiperazine and dihydroquinoxalinone libraries via a UDC (Ugi/de-Boc/cyclization) strategy in combination with ethylglyoxalate. The methodology represents a ‘three step, one-pot procedure’, employing the Ugi multi-component reaction (MCR), followed by Boc deprotection and cyclization.

Novel safety-catch linker and its application with a Ugi/De- BOC/cyclization (UDC) strategy to access carboxylic acids, 1,4- benzodiazepines, diketopiperazines, ketopiperazines and dihydroquinoxalinones

Abstract This communication reveals the synthesis and application of a novel resin bound isonitrile. The resin is an example of a novel safety-catch linker which upon BOC-activation can be resin cleaved with a variety of nucleophiles. Use of this polymer supported isonitrile in the Ugi multi-component reaction (MCR), followed by resin clipping and cyclization allows access to diverse arrays of 1,4-benzodiazepine-2,5-diones, diketopiperazines and ketopiperazines respectively. The methoxide safety-catch clipping strategy and subsequent solution phase cyclization offers similar advantages to a traceless linker.

Emerging molecular diversity from the intra-molecular Ugi reaction: iterative efficiency in medicinal chemistry

This review details a now established area within the isonitrile multi-component reaction (IMCR) field of study, namely employing bi-functional reagents in the Ugi reaction for the construction of screening sets with the additional element or even possibly ‘metric’ of enhanced ‘iterative efficiency potential’ The concept of ‘iterative efficiency’ will be briefly introduced, coupled with discussion on new synthetic routes to select bi-functional IMCR precursors and their use in the generation of pharmacologically relevant ‘molecular diversity’

THE SOLUTION PHASE SYNTHESIS OF DIKETOPIPERAZINE LIBRARIES VIA THE UGI REACTION : NOVEL APPLICATION OF ARMSTRONG'S CONVERTIBLE ISONITRILE

Abstract This communication describes the generation of high-yielding solution phase diketopiperazine libraries via a ‘3-step, 1-pot’ procedure, employing the Ugi multi-component reaction (MCR), followed by BOC deprotection and cyclization to diketopiperazine (DKP). Exploitation of Armstrongs convertible isonitrile in the Ugi reaction utilising an ‘internal nucleophile’ approach for diketopiperazine formation is presented.

Two-step solution-phase synthesis of novel benzimidazoles utilizing a UDC (Ugi/de-Boc/cyclize) strategy

Abstract The novel solution-phase synthesis of an array of biologically relevant benzimidazoles in a simple two-step procedure is revealed. Transformations are carried out in excellent yield by condensation of mono-Boc protected ortho-phenylene diamine and supporting Ugi reagents. Subsequent acid treatment and evaporation affords benzimidazoles in good to excellent yield. The described protocol represents a highly attractive solution-phase procedure for the rapid generation of benzimidazole libraries.

Recent Advances in the Design, Synthesis, and Biological Evaluation of Selective DYRK1A Inhibitors: A New Avenue for a Disease Modifying Treatment of Alzheimer’s?

With 24.3 million people affected in 2005 and an estimated rise to 42.3 million in 2020, dementia is currently a leading unmet medical need and costly burden on public health. Seventy percent of these cases have been attributed to Alzheimers disease (AD), a neurodegenerative pathology whose most evident symptom is a progressive decline in cognitive functions. Dual specificity tyrosine phosphorylation regulated kinase-1A (DYRK1A) is important in neuronal development and plays a variety of functional roles within the adult central nervous system. The DYRK1A gene is located within the Down syndrome critical region (DSCR) on human chromosome 21 and current research suggests that overexpression of DYRK1A may be a significant factor leading to cognitive deficits in people with Alzheimers disease (AD) and Down syndrome (DS). Currently, treatment options for cognitive deficiencies associated with Down syndrome, as well as Alzheimers disease, are extremely limited and represent a major unmet therapeutic need. Small molecule inhibition of DYRK1A activity in the brain may provide an avenue for pharmaceutical intervention of mental impairment associated with AD and other neurodegenerative diseases. We herein review the current state of the art in the development of DYRK1A inhibitors.

MCC/SNAr methodology. Part 1: Novel access to a range of heterocyclic cores

The novel solution-phase syntheses of arrays of biologically relevant indazolinones, benzazepines and benzoxazepines, utilizing multi-component condensation (MCC)/SNAr methodology is reported. Reaction of commercially available 2-fluoro-5-nitrobenzoic acid with an aldehyde, isonitrile and a primary amine tethered to a Boc-protected internal amino or hydroxyl nucleophile, affords the Ugi product in good yield. Subsequent acid treatment followed by proton scavenging promotes cyclization of internal amino nucleophiles to a variety of ring sizes. Base treatment alone is sufficient to generate benzoxazepines. Interestingly, this communication also introduces a highly efficient two-step route to benzimidazoles.

Ugi/Aldol Sequence: Expeditious Entry to Several Families of Densely Substituted Nitrogen Heterocycles

All it takes is the Aldol Nitrogen containing heterocycles have been assembled by means of unprecedented domino processes, designed to take advantage of diversity assembly via strategically decorated Ugi products. The aldol reaction is the second common denominator which enables sequences of up to 5 steps in one pot producing unique molecular architecture in rapid fashion.

The design, synthesis, and evaluation of 8 hybrid DFG-out allosteric kinase inhibitors: A structural analysis of the binding interactions of Gleevec®, Nexavar®, and BIRB-796

The majority of kinase inhibitors developed to date are competitive inhibitors that target the ATP binding site; however, recent crystal structures of Gleevec (imatinib mesylate, STI571, PDB: 1IEP), Nexavar (Sorafenib tosylate, BAY 43-9006, PDB: 1UWJ), and BIRB-796 (PDB: 1KV2) have revealed a secondary binding site adjacent to the ATP binding site known as the DFG-out allosteric binding site. The recent successes of Gleevec and Nexavar for the treatment of chronic myeloid leukemia and renal cell carcinoma has generated great interest in the development of other kinase inhibitors that target this secondary binding site. Here, we present a structural comparison of the important and similar interactions necessary for Gleevec(R), Nexavar, and BIRB-796 to bind to their respective DFG-out allosteric binding pockets and the selectivity of each with respect to c-Abl, B-Raf, and p38alpha. A structural analysis of their selectivity profiles has been generated from the synthesis and evaluation of 8 additional DFG-out allosteric inhibitors that were developed directly from fragments of these successful scaffolds.

Aldol Reactions in Multicomponent Reaction Based Domino Pathways: A Multipurpose Enabling Tool in Heterocyclic Chemistry

The aldol reaction has been evaluated in combination with the Ugi multicomponent reaction to assemble richly decorated mono- and polycyclic systems via expeditious cascade pathways. A small collection of pyrrolinones was generated thereof, and the scarcely accessible pyridoquinoxalinedione scaffold was also prepared by designing an additional nucleophilic substitution step in this domino sequence requiring minimal operational effort.