The Total Synthesis of the Fungal Metabolite Diversonol.

Abstract

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A versatile Diels–Alder approach to functionalized hydroanthraquinones

“…The results of this work suggest that the electronic rather than the steric nature of the substituents had the strongest influence on the regioselective outcome of the reaction. The incorporation of functionalities like methoxy groups into the anthraquinone derivatives paves the way for further modifications such as the installation of a tetrahydroxanthone subunit, for example, via a domino oxa-Michael–aldol condensation [ 38 ], to facilitate anthraquinone–xanthone heterodimers.…”

Catalytic enantioselective reductive desymmetrisation of achiral and meso compounds

“…Noteworthy results have been observed in the enantioselective desymmetrisation of dicarbonyl compounds towards hydroxyketones employing chiral cobalt complexes 70 69,70 or oxazaborolidines 73 and 76 71,72 as the catalysts, and boron-based reagents as the stoichiometric reducing agents (e.g. NaBH 4 or catecholborane).…”

“…Desymmetrising CBS (Corey-Bakshi-Shibata) reduction also has been efficiently employed using dicarbonyl compounds. The Bra ¨se 71 and Corey 72 groups have recently reported the preparation of highly enantioenriched synthetic intermediates using this chemistry (Schemes 6(b) and (c)). Whilst Bra ¨se et al employed standard conditions for the CBS desymmetrisations leading to the tricyclic hydroxyketone 75 indicated in Scheme 6(b) with high enantioselectivity, 71 Corey et al used modified reduction conditions involving substoichiometric amounts of N,N-diethylaniline to accelerate the reaction and control the final stereochemistry.…”

“…The Bra ¨se 71 and Corey 72 groups have recently reported the preparation of highly enantioenriched synthetic intermediates using this chemistry (Schemes 6(b) and (c)). Whilst Bra ¨se et al employed standard conditions for the CBS desymmetrisations leading to the tricyclic hydroxyketone 75 indicated in Scheme 6(b) with high enantioselectivity, 71 Corey et al used modified reduction conditions involving substoichiometric amounts of N,N-diethylaniline to accelerate the reaction and control the final stereochemistry. These modified conditions led to the opposite stereocourse of the reaction, and the authors hypothesised that activation of the substrate by its coordination to the oxazaborolidine, followed by hydride delivery from the catecholborane-N,N-diethylaniline complex, could account for this stereochemistry.…”

The first total synthesis of nidulalin A, a dihydroxanthone possessing multiple bioactivities

“…2,3 Although natural products having the dihydroxanthone skeleton have been seen to be widespread, [4][5][6][7][8] only a few total syntheses have been achieved. 9,10 Interested in the structure and bioactivities of nidulalin A, we embarked on the synthetic studies of the natural product.…”