Publications
11 results found
Allen LAT, Raclea R-C, Natho P, et al., 2021, Recent advances in the synthesis of α-amino ketones, Organic & Biomolecular Chemistry, Vol: 19, Pages: 498-513, ISSN: 1477-0520
<p>This review on α-amino ketone synthesis collates and evaluates developments made in this area over the past decade, with an extended discussion on functional group compatibility, resultant product substitution patterns, and medicinal applications.</p>
Natho P, Yang T, Allen L, et al., 2021, An entry to 2-(cyclobut-1-en-1-yl)-1H-indoles through a cyclobutenylation/deprotection cascade, Organic and Biomolecular Chemistry, ISSN: 1477-0520
Natho P, Annie R, Greenfield J, et al., 2020, Regioselective synthesis of 1- and 4-tetralones from heteroaryl-3-cyclobutanols, Tetrahedron, Vol: 76, ISSN: 0040-4020
Herein we describe the first transition-metal-free ring expansion of four-membered rings to 1-tetralones from 3-substituted heteroaromatic compounds, and the first example of an oxetanol ring expansion to an oxa-tetralone. We also experimentally investigate the mechanism of the silver-mediated ring expansion and elucidate the active oxidant in these systems using electrochemical techniques.
Raclea R-C, Natho P, Allen L, et al., 2020, Oxidative deconstruction of azetidinols to α-Amino ketones, Journal of Organic Chemistry, Vol: 85, Pages: 9375-9385, ISSN: 0022-3263
A silver-mediated synthesis of α-amino ketones via the oxidative deconstruction of azetidinols has been developed using a readily scalable protocol with isolated yields up to 80%. The azetidinols are easily synthesized in one step and can act as protecting groups for these pharmaceutically relevant synthons. Furthermore, mechanistic insights are presented and these data have revealed that the transformation is likely to proceed through the β-scission of an alkoxy radical, followed by oxidation and C–N cleavage of the resulting α-amido radical.
Natho P, Allen LAT, Parsons PJ, 2020, Recent advances in the ring expansion of cyclobutanols, oxetanols, and azetidinols, Tetrahedron Letters, Vol: 61, Pages: 1-9, ISSN: 0040-4039
The number of developed methodologies for the ring expansion of cyclobutanol rings to five, six and seven-membered rings has increased significantly over the last six years. In this timeframe, the semipinacol rearrangement of vinyl-group containing cyclobutanols to cyclopentanones has been advanced under photoredox and electrochemical conditions, enabling the concomitant introduction of a wide array of functional groups. The expansion to 1- and 4-tetralones has been achieved for the first time under transition-metal-free conditions and even expansion to seven-membered rings has been demonstrated under rhodium catalysis. In this article, we will critically discuss the scope, application and mechanistic studies of procedures published since 2013, and provide a short outlook on the emerging potential for further development in this area.
Natho P, Allen LAT, White AJP, et al., 2019, A transition-metal-free access to heteroaromatic-fused 4-tetralones by the oxidative ring expansion of the cyclobutanol moiety, The Journal of Organic Chemistry, Vol: 84, Pages: 9611-9626, ISSN: 0022-3263
Advances in the transition-metal-free cyclobutanol ring expansion to 4-tetralones under N-bromosuccinimide mediation are described. We have expanded the scope of this ring expansion methodology and investigated the effect substituents on the aromatic ring, and the cyclobutanol moiety, have on the outcome of the reaction. Limitations with certain substituents on the cyclobutanol moiety are also described. Further experimental evidence to support our mechanistic understanding is disclosed, and we now preclude the suggested involvement of a primary radical for this transformation.
Natho P, Kapun M, Allen L, et al., 2018, Regioselective transition-metal-free oxidative cyclobutanol ring expansion to 4-tetralones, Organic Letters, Vol: 20, Pages: 8030-8034, ISSN: 1523-7052
A facile and transition-metal-free ring expansion of the cyclobutanol moiety to 4-tetralones fused to heteroaromatic systems is described. The oxidative ring expansion proceeds rapidly and regioselectively through mediation by N-bromosuccinimide and acetonitrile in satisfactory to good yields. The preparation of precursors, as well as the ring expansion have proven to be scalable and are straightforward to carry out
Parsons PJ, Allen LAT, Jones DR, et al., 2017, Approaches to the synthesis of highly substituted aromatic and fused rings: metal-catalysed versus thermal cyclisation, Synthesis, Vol: 50, Pages: 84-101, ISSN: 0039-7881
A domino reaction has been used for the construction of lactonamycin derivatives. This research led to a comparison study between palladium-mediated cascade cyclisations and thermal alkyne [2+2+2] cyclisations. A palladium-mediated cyclisation of alkenyl bromides with alkynes and furans has been shown to furnish highly substituted aromatic rings. Penta- and hexasubstituted aromatic rings have also been prepared by the thermolysis of suitably substituted alkynes under microwave conditions. Tetrasubstituted pyridines can also be prepared using nitriles instead of alkynes. This work will provide a new and interesting array of drug templates; mechanistic details are discussed for both reaction series.
Parsons PJ, Jones DR, Walsh LJ, et al., 2017, An approach to the core of lactonamycin, Organic Letters, Vol: 19, Pages: 2533-2535, ISSN: 1523-7060
A cascade reaction has been developed for the synthesis of lactonamycin. In this paper, we demonstrate that a transition-metal-free thermal ene–diyne cyclization can be used for the construction of the entire core of the antibiotic lactonamycin and anticancer agent lactonamycin Z.
Parsons PJ, Jones DR, Padgham AC, et al., 2016, ChemInform Abstract: A New Approach for the Synthesis of Highly Substituted Aromatic Rings: The Alkyne-Mediated Approach., ChemInform, Vol: 47, ISSN: 0931-7597
Parsons PJ, Jones DR, Padgham AC, et al., 2016, A New Approach for the Synthesis of Highly Substituted Aromatic Rings: The Alkyne-Mediated Approach, CHEMISTRY-A EUROPEAN JOURNAL, Vol: 22, Pages: 3981-3984, ISSN: 0947-6539
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