6540-66-5Relevant articles and documents
A biomimetic type expedient approach to the tricyclic core of xyloketals. Application to a short, stereocontrolled synthesis of alboatrin and a remarkable epi to natural isomerisation
Sarkar, Debayan,Ghosh, Subrata,Venkateswaran, Ramanathapuram V.
, p. 1431 - 1434 (2009)
An expedient synthesis of the linear tetrahydrofurano benzopyran ring system of xyloketals is described involving an ortho ester Claisen rearrangement and an intramolecular cationic cyclisation. This strategy was applied for a short, stereocontrolled and
Regioselective synthesis of salicylates and acetophenones by formal [3+3]-cyclocondensations of 3-oxoorthoesters with 1,3-bis(trimethylsilyloxy)-1,3-butadienes
Gütlein, J?rg-Peter,Lubbe, Mathias,Feist, Holger,Villinger, Alexander,Langer, Peter
, p. 1 - 26 (2020/12/23)
A variety of 4-methoxysalicylates and related polyketide-type phenols are regioselectively prepared by formal [3+3] cyclocondensations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes with 3-oxo-orthoesters. Cycloalkyl-substituted salicylates were prepared for the first time.
Total synthesis and anti-inflammatory evaluation of violacin A and its analogues
Liu, Qingyin,Mu, Yu,An, Qi,Xun, Jiali,Ma, Jian,Wu, Wenxi,Xu, Minjuan,Xu, Jun,Han, Li,Huang, Xueshi
, (2019/11/26)
A concise total synthesis of an exceedingly potent anti-inflammatory agent violacin A as well as the preparation of thirty analogues of this lead from commercially available orcinol are described. Highlights of our synthetic efforts involve Friedel-Crafts acylation, the regioselective etherification and esterification of phenolic hydroxyl groups, and Baker-Venkatamaran rearrangement to form basic skeleton of violacin A. The deprotection reaction with Pd-catalytic was involved to avoid the elimination of the hemiacetal hydroxyl at C2. In addition, all synthetic compounds were screened for anti-inflammatory activity against nitric oxide (NO) production using lipopolysaccharide (LPS)-induced Raw264.7 cells. A range of violacin A derivatives 11b, 11d, 11f, 12e, 12g, 13g, 17d-g exhibited stronger anti-inflammatory effect than that of violacin A. Notably, halogeno-benzyloxy substituent at C-7 were favourable for anti-inflammatory activities of violacin A derivatives. Additionally, Western blot results indicated halogeno-benzyloxy derivatives inhibited pro-inflammatory cytokines releases correlated with the suppression of NF-κB signaling pathway.
Biomimetic type approach to the tricyclic core of xyloketals. Application to a short, stereocontrolled synthesis of alboatrin and first synthesis of xyloketal G
Sarkar, Debayan,Venkateswaran, Ramanathapuram V.
experimental part, p. 4559 - 4568 (2011/07/08)
A convenient approach to the linear tetrahydrofurano benzopyran ring system of xyloketals is described. An orthoester Claisen rearrangement of a chromenol and an intra-molecular cationic cyclization are the key steps in the synthesis. A short, stereocontrolled and high yield synthesis of the phytotoxic metabolite alboatrin was achieved employing this strategy. A unique case of Lewis acid catalyzed isomerization of epi-alboatrin to alboatrin was observed. Subsequently this methodology was extended for the first total synthesis of xyloketal G, where a one pot reaction of three steps viz., acetylation, isomerization and demethylation occurred during acetylation of a mixture of nor-o-methyl xyloketal G and nor-o-methyl epi xyloketal G in presence of AlCl3 to furnish xyloketal G in very good overall yield.
Formal synthesis of both atropomers of desertorin C and an example of chirality transfer from a biphenyl axis to a spiro centre and its reverse
Baker, Robert W.,Kyasnoor, Rekha V.,Sargent, Melvyn V.,Skelton, Brian W.,White, Allan H.
, p. 487 - 506 (2007/10/03)
In connection with the synthesis of 4,4′,7,7′-tetramethoxy-5,5′-dimethyl-6,8′-bicoumarin (desertorin C) (11) in enantiopure form, the diastereomeric ratios of the products of the reactions between 2-isopropyloxy-6-methoxy-4-methylphenylmagnesium bromide (24) and (4S)-4-isopropyl-2-(2,3,5-trimethoxyphenyl)-4,5-dihydrooxazole (23), between 2,4-dimethoxy-6-methylphenylmagnesium bromide (37) and (4S)-4-isopropyl-2-(2,3-dimethoxy-5-methylphenyl)-4,5-dihydrooxazole (36), and between 2,4-dimethoxy-6-(t-butyldimethylsilyloxy)methylphenyl-magnesium bromide (46) and the oxazole (36) were explored. The major product of the last mentioned reaction was converted into (S,4S)-4-isopropyl-2-(2′-hydroxymethyl-4′,6,6′-trimethoxy-4- methyl-1,1′-biphenyl-6-yl)-4,5-dihydroxazole (49), the axial configuration of which was confirmed by single crystal X-ray structural determination. The similar product (S,4S)-2-(2′,4′,6-trimethoxy-4,6′-dimethyl-1,1′- biphenyl-6-yl)-4,5-dihydrooxazole (43) was converted into (S)-1-(2,4′,6′-trimethoxy-4,6′-biphenyl-2-yl)ethanone (57) which furnished (S)-1-(2′,4′,6-trimethoxy-4,6′-dimethyl-1,1′-biphenyl-2- yl)acetamide (58) (43%) and (S)-2,7′-dimethoxy-3′,5′,6-trimethylspiro[cyclohexa-2,5-diene- 1,1′-(1H)isoindole]-4-one (61) (30%) on Schmidt rearrangement. The dienone (61) on reduction and methylation regenerated the ketone (57). The methodology of Lipschutz was adapted for the synthesis of both enantiomers of 1,1′-(2′,4-dihydroxy-6,6′-dimethoxy-2,4′- dimethylbiphenyl-3,3′-diyl)bisethanone (32) and (83) which constitutes a formal synthesis of both enantiomers of desertorin C. CSIRO 2000.
