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
Flexible Tetrahydropyran Synthesis from Homopropargylic Alcohols Using Sequential Pd–Au Catalysis
作者:Jungjoon Kim、Wook Jeong、Young Ho Rhee
DOI:10.1021/acs.orglett.6b03532
日期:2017.1.6
flexible synthetic method toward highly substituted tetrahydropyran is reported. The key transformation involves atom-efficient sequential metal catalysis consisting of Pd-catalyzed addition of homopropargylicalcohols to alkoxyallene and the subsequent gold(I)-catalyzed cycloisomerization. Notably, this method gives access to both 2,6-cis- and 2,6-trans-tetrahydropyrans possessing diverse substitution patterns
Synthesis of the Griseusin B Framework via a One-Pot Annulation–Methylation–Double Deprotection–Spirocyclization Sequence
作者:Briar J. Naysmith、Margaret A. Brimble
DOI:10.1021/ol400686f
日期:2013.4.19
A highly convergent synthesis of the griseusin B scaffold is described. The key step involves an efficient one-pot Hauser–Kraus annulation–methylation–double deprotection–spirocyclization sequence that directly affords the target parent tetracyclic ringsystem.
The second generation synthesis of (+)-pseudodeflectusin (1), a potential antitumor agent, has been achieved. The key synthetic step is the cascade reaction involving Diels-Alder reaction, lactonization, and decarboxylation to give cycloadduct 6 with complete regioselectivity in good yield. We found that NaH is the best base to facilitate the Diels-Alder reaction of hydroxypyrone 7 with alkyne 8. The present synthetic route enables the total synthesis of (+)-1 in only five-steps from the known compounds 7 and 8. (C) 2010 Elsevier Ltd. All rights reserved.