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Dive into the research topics where Jonathan H. George is active.

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Featured researches published by Jonathan H. George.


Organic Letters | 2010

Enantiospecific, biosynthetically inspired formal total synthesis of (+)-liphagal.

Jonathan H. George; Jack E. Baldwin; Robert M. Adlington

A biosynthetically inspired synthesis of (+)-liphagal has been achieved from (+)-sclareolide in 13 steps (9% overall yield). The key step is a biomimetic ring expansion of a highly stabilized benzylic carbocation, which generates the seven-membered ring and the benzofuran of the natural product in a single cascade reaction.


Organic Letters | 2010

Biomimetic Synthesis of Polycyclic Polyprenylated Acylphloroglucinol Natural Products Isolated from Hypericum papuanum

Jonathan H. George; Micha D. Hesse; Jack E. Baldwin; Robert M. Adlington

Biomimetic syntheses of three polycylic polyprenylated acylphloroglucinol natural products isolated from Hypericum papuanum, ialibinone A, ialibinone B, and hyperguinone B, have been accomplished by selective oxidative cyclizations of the proposed biosynthetic precursor 5, which was synthesized from phloroglucinol in three steps.


Organic Letters | 2011

Structural Reassignment of Cytosporolides A–C via Biomimetic Synthetic Studies and Reinterpretation of NMR Data

Justin T. J. Spence; Jonathan H. George

A structure revision for the recently isolated fungal meroterpenoids, cytosporolides A-C, is suggested based on biosynthetic speculation and reinterpretation of existing spectroscopic data. The structure revision is supported by a biomimetic synthetic study, featuring a [4 + 2] cycloaddition reaction between a presumed o-quinone methide intermediate and β-caryophyllene.


Organic Letters | 2012

Biomimetic Total Synthesis of (±)-Garcibracteatone

Henry P. Pepper; Hiu C. Lam; Witold M. Bloch; Jonathan H. George

The polycyclic polyprenylated acylphloroglucinol natural product garcibracteatone has been synthesized in four steps from phloroglucinol, using a strategy based on biosynthetic speculation. The key biomimetic transformation is a cascade of 7-endo-trig and 5-exo-trig radical cyclizations followed by a terminating aromatic substitution reaction.


Organic Letters | 2009

Total Synthesis of (+)-Azinothricin and (+)-Kettapeptin

Karl J. Hale; Soraya Manaviazar; Jonathan H. George; Marcus Walters; Stephen M. Dalby

Asymmetric total syntheses of (+)-azinothricin and (+)-kettapeptin have been completed through a common new pathway that exploits a highly chemoselective coupling reaction between the fully elaborated cyclodepsipeptide 5 and the glycal activated esters 3 and 4 at the final stages of both respective syntheses.


Organic Letters | 2013

Biomimetic Total Synthesis of ent-Penilactone A and Penilactone B

Justin T. J. Spence; Jonathan H. George

The total synthesis of ent-penilactone A and penilactone B has been achieved via biomimetic Michael reactions between tetronic acids and o-quinone methides. A five-component cascade reaction between a tetronic acid, formaldehyde, and a resorcinol derivative that generates four carbon-carbon bonds, one carbon-oxygen bond, and two stereocenters in a one-pot synthesis of penilactone A is also reported.


Organic Letters | 2015

Total Synthesis and Structure Revision of (−)-Siphonodictyal B and Its Biomimetic Conversion into (+)-Liphagal

Adrian W. Markwell-Heys; K. Kuan; Jonathan H. George

The structure of siphonodictyal B has been reassigned on the basis of the total synthesis of both possible C-8 epimers. The revised structure of siphonodictyal B was converted into liphagal by acid catalyzed rearrangement of a proposed epoxide intermediate. This biomimetic cascade features a succession of four distinct reactions (epoxidation, o-quinone methide formation, ring expansion, and benzofuran formation) that occur in a one-pot operation under mild conditions. During these studies we also isolated a surprisingly stable o-quinone methide that supports our mechanistic proposal for liphagal biosynthesis.


Angewandte Chemie | 2016

Biomimetic Total Synthesis of Hyperjapones A–E and Hyperjaponols A and C

Hiu C. Lam; Justin T. J. Spence; Jonathan H. George

Hyperjapones A-E and hyperjaponols A-C are complex natural products of mixed aromatic polyketide and terpene biosynthetic origin that have recently been isolated from Hypericum japonicum. We have synthesized hyperjapones A-E using a biomimetic, oxidative hetero-Diels-Alder reaction to couple together dearomatized acylphloroglucinol and cyclic terpene natural products. Hyperjapone A is proposed to be the biosynthetic precursor of hyperjaponol C through a sequence of: 1) epoxidation; 2) acid-catalyzed epoxide ring-opening; and 3) a concerted, asynchronous alkene cyclization and 1,2-alkyl shift of a tertiary carbocation. Chemical mimicry of this proposed biosynthetic sequence allowed a concise total synthesis of hyperjaponol C to be completed in which six carbon-carbon bonds, six stereocenters, and three rings were constructed in just four steps.


Organic Letters | 2012

Synthesis of a Liphagal–Frondosin C Hybrid and Speculation on the Biosynthesis of the Frondosins

Henry P. Pepper; K. Kuan; Jonathan H. George

A hypothesis for the biosynthesis of the frondosins A-E is presented. Synthesis of a liphagal-frondosin C hybrid molecule has been achieved, with the frondosin C 6-7-5-6 ring system being constructed by a photochemical process that follows an intramolecular Paternò-Büchi reaction/fragmentation pathway.


Chemical Communications | 2010

Total synthesis of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin: powerful new inhibitors of β-catenin/TCF4- and E2F-mediated gene transcription

Karl J. Hale; Soraya Manaviazar; Jonathan H. George

Herein we describe our asymmetric total syntheses of (+)-A83586C, (+)-kettapeptin and (+)-azinothricin. We also demonstrate that molecules of this class powerfully inhibit beta-catenin/TCF4- and E2F-mediated gene transcription within malignant human colon cancer cells at low drug concentrations.

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Hiu C. Lam

University of Adelaide

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Karl J. Hale

University College London

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K. Kuan

University of Adelaide

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Marcus Walters

University College London

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