Total Synthesis of Apicularen A through Transannular Pyran Formation

Petri, Andreas F.; Bayer, Alexander; Maier, Martin E.

doi:10.1002/anie.200460760

Cited by 61 publications

(30 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Unfortunately, this protocol resulted in O ‐desilylation as well as the desired acetonide deprotection and a complex mixture of products was observed. Other deprotection conditions were then investigated, including the use of camphorsulfonic acid (CSA, 2 equiv)34 or SnCl 2 (4 equiv),35 though in both instances only starting material was recovered. The use of TFA/water in CH 2 Cl 2 at room temperature,34 however, appeared more promising, with 9 being obtained in a modest (20 %) yield, along with a mixture of partially desilylated products.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Biological Activity of the Lipoteichoic Acid Anchor from Streptococcus sp. DSM 8747

et al. 2012

View full text Add to dashboard Cite

In this study, the role of lipoteichoic acid (LTA) anchors in the activation of the innate immune response was investigated through the chemical synthesis of a series of LTA derivatives and the determination of their ability to induce NO production in bone marrow-derived macrophages (BMM). To this end, an efficient synthesis of the sn-3-O-(α-D-galactofuranosyl)-1,2-di-O-acylglycerol LTA core was developed, which was then used as a key structure to produce both phosphate and glycerylphosphate-funtionalised LTA anchors, as well as galactofuranosyldiglycerides with different fatty acid chain lengths. With a series of LTA anchors in hand, we then determined the effect of these glycolipids on the innate immune response by exploring their capacity to activate macrophages. Here, we report that several of the LTA-derivatives were able to induce NO production by BMMs. In general, the unnatural (sn-1) core glycolipid anchors showed lower levels of activity than the corresponding natural (sn-3) analogues, and the activity of the glycolipids also appears to be dependent on the length of lipid present, with an optimum lipid length of C20 for the sn-3 derivatives. Interestingly, a triacylated anchor and the 6-O-phosphorylated anchor, showed only modest activity, while the 6-O-glycerophosphorylated derivative was unable to induce NO production. Taken as a whole, our results highlight the subtle effects that glycolipid length can have on the ability to activate BMMs.

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis and Biological Activity of the Lipoteichoic Acid Anchor from Streptococcus sp. DSM 8747

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Thus TPAP/NMO/PMS/ CH 2 Cl 2 was used for two such steps in the synthesis of the phytohormone abscisic acid [77]; synthesis of the antitumour styryllactone (+)-altholactone involved a lactol to lactone step [78]; one step in the synthesis of the macrolide altohyrtin A [79]; the cytotoxic benzolactone enamide apicularen A [80]; the anti-parasitic avermectin-B1a ( Fig. 2.6) -this also involved oxidation of a secondary alcohol [81,82]; the AChE inhibitor (+)-arisugacin A and B (secondary alcohol to ketone step also) [83]; the eunicellin astrogorgin [84]; the antibiotic (−)-borrelidin (two such steps involved) [85]; the neurotoxin brevetoxin B [86,87]; the toxic metabolite (−)-epicylindrospermine [88]; the anti-growth factor 2-epibotcinolide (lactone to ketolactone TPAP oxidation also involved) [89], the antifungal gambieric acids A and C (there is also a secondary alcohol to ketone TPAP-catalysed step) [90]; the ether toxin gambierol (two such steps; also a secondary alcohol to ketone) [91]; the cytotoxic gymnocin-A (also three secondary to ketone steps) [92]; the acetogenin 10-hydroxyasimicin [93] and the xenicane diterpene 4-hydroxydictyolactone [94].…”

Section: Natural Product/pharmaceutical Syntheses Involving Primary Amentioning

confidence: 99%

Oxidation of Alcohols, Carbohydrates and Diols

Griffith

2009

Catalysis by Metal Complexes

View full text Add to dashboard Cite

This is one of the most important classes of oxidation effected by Ru complexes, particularly by RuO 4 , [RuO 4 ] − , [RuO 4 ] 2− and RuCl 2 (PPh 3 ) 3 , though in fact most Ru oxidants effect these transformations. The chapter covers oxidation of primary alcohols to aldehydes (section 2.1), and to carboxylic acids (2.2), and of secondary alcohols to ketones (2.3). Oxidation of primary and secondary alcohol functionalities in carbohydrates (sugars) is dealt with in section 2.4, then oxidation of diols and polyols to lactones and acids (2.5). Finally there is a short section on miscellaneous alcohol oxidations in section 2.6.In this chapter the first of the two most important categories of oxidations catalysed by Ru complexes (the other being alkene and alkyne oxidations in Chapter 3) are considered. The approach in this and subsequent chapters differs from that of Chapter 1, concentrating here on the substrate rather than on the oxidant. The text is divided into the categories of alcohols and their oxidations. There are summaries in section 2.3.6 of systems of limited applicability which are mentioned only in Chapter 1, and in section 2.3.7 of large-scale (>1 g) oxidations.The first oxidations of alcohols by stoicheiometric RuO 4 /H 2 O were reported in 1958, of primary alcohols to aldehydes or carboxylic acids and secondary alcohols to ketones [1]. The first Ru-catalysed oxidation of an alcohol was reported in 1965 when Parikh and Jones used RuO 2 /aq. Na(IO 4 )/CCl 4 1 ( Table 2.3) [2] to oxidise secondary alcohol groups in carbohydrates.Oxidation of alcohols is the most frequently reviewed topic for Ru-catalysed oxidations [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Mechanisms of alcohol oxidation by Ru complexes have been reviewed [21].

show abstract

“…In addition to its fascinating biological activities, the structural novelty of apicularen A 47 has also attracted the attention of the synthetic community. To date, several total syntheses of apicularen A have been completed 45 along with several formal total syntheses. 46 Whereas all of the previous syntheses of the apicularen A 47 derived their asymmetry by a resolution or from the chiral pool, we were interested in a de novo asymmetric approach that would use asymmetric catalysis to install the four stereocenters in apicularen A 47 from achiral starting materials.…”

Section: (–)-Apicularen A43mentioning

confidence: 99%