Total synthesis and confirmation of the absolute stereochemistry of semiviriditoxin, a naphthopyranone metabolite from the fungus Paecilomyces variotii
作者:Nichole P.H. Tan、Christopher D. Donner
DOI:10.1016/j.tet.2009.03.016
日期:2009.5
The first total synthesis of (S)-semiviriditoxin 2 is described. The approach utilizes a tandem Michael–Dieckmann reaction between ortho-toluate 5 and dihydropyran-2-one 6 to construct the naphthopyranone core, the dihydropyran-2-one 6 being prepared from (R)-1,2-epoxy-4-butanol. Spectroscopic comparison of synthetic (S)-semiviriditoxin 2 with (R)-semivioxanthin 3, prepared in four steps from (R)-propylene
In this article, we report the total synthesis of 6-deoxydihydrokalafungin (DDHK), a key biosynthetic intermediate of a dimeric benzoisochromanequinone antibiotic, actinorhodin (ACT), and its epimer, epi-DDHK. Tricyclic hemiacetal with 3-siloxyethyl group was subjected to Et3SiH reduction to establish the 1,3-cis stereochemistry in the benzoisochromane, and a subsequent oxidation/deprotection sequence
Naphthopyranone synthesis via the tandem Michael–Dieckmann reaction of ortho-toluates with 5,6-dihydropyran-2-ones
作者:Nichole P.H. Tan、Christopher D. Donner
DOI:10.1016/j.tetlet.2008.04.112
日期:2008.6
The tandem Michael-Dieckmann reaction between a series of ortho-toluates and the alpha,beta-unsaturated lactone 25 is described. The tandem reaction delivers substituted naphthopyranones in moderate (20-49%) yields, whilst limitations in the tolerance of this reaction for different substituents on the ortho-toluate are identified. Crown Copyright (C) 2008 Published by Elsevier Ltd. All rights reserved.
The divergent asymmetric synthesis of kalafungin, 5-epi-frenolicin B and related pyranonaphthoquinone antibiotics
作者:Christopher D. Donner
DOI:10.1016/j.tet.2012.10.012
日期:2013.1
A divergent, asymmetric method for the synthesis of pyranonaphthoquinones is reported. The synthetic strategy applies a Staunton–Weinreb annulation between substituted ortho-toluates and the (R)-pyran-2-one 7 to construct the key naphthopyranone intermediates. Stereoselective introduction of either a methyl or propyl C5 alkyl substituent by use of Grignard addition/silane-mediated reduction and a sequence
Total synthesis of (+)-kalafungin using a tandem Michael–Dieckmann approach
作者:Christopher D. Donner
DOI:10.1016/j.tetlet.2007.10.058
日期:2007.12
A stereoselective synthesis of the antibiotic kalafungin 1 is reported. A key step involved the tandem Michael–Dieckmann reaction between methyl 2-methoxy-6-methylbenzoate 11 and the α,β-unsaturated lactone (R)-6-(2-(tert-butyldimethylsilyloxy)ethyl)-4-methoxy-5,6-dihydropyran-2-one 10, which was prepared from (S)-aspartic acid. The C5 alkyl substituent was introduced by the use of methylmagnesium