214892-50-9Relevant academic research and scientific papers
Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step
Nocquet, Pierre-Antoine,Macé, Aurélie,Legros, Frédéric,Lebreton, Jacques,Dujardin, Gilles,Collet, Sylvain,Martel, Arnaud,Carboni, Bertrand,Carreaux, Fran?ois
, p. 2949 - 2955 (2018/12/13)
In this paper, a new access to several chiral 3-aminoglycals as potential precursors for glycosylated natural products is reported from a common starting material, (?)-methyl-L-lactate. The stereodivergent strategy is based on the implementation of a ring
Synthesis of epothilones via a silicon-tethered RCM reaction
Gaich, Tanja,Mulzer, Johann
, p. 1311 - 1313 (2007/10/03)
(Chemical Equation Presented) A short synthesis of epothilone B and D is reported. The key step for generating the C12-13-trisubstituted Z-double bond uses a ring-closing metathesis reaction of a disiloxane to form a nine-membered silicon-tethered ring.
Studies on the synthesis of landomycin A: Synthesis and glycosidation reactions of L-rhodinosyl acetate derivatives
Roush,Bennett,Roberts
, p. 6389 - 6393 (2007/10/03)
An efficient, eight-step synthesis of L-rhodinosyl acetate derivative 3 is described. The synthesis originates from methyl (S)-lactate and involves a highly stereoselective, chelate-controlled addition of allyltributylstannane to the lactaldehyde derivative 7. The β-anomeric configuration of 3 was established with high selectivity by acetylation of the pyranose precursor with Ac2O and Et3N in CH2Cl2. Preliminary studies of glycosidation reactions of 3 and L-rhodinosyl acetate 10 containing a 3-O-TES ether revealed that these compounds are highly reactive glycosidating agents and that trialkylsilyl triflates are effective glycosylation promoters. The best conditions for reactions with 15 as the accepter involved use of diethyl ether as the reaction solvent and 0.2 equiv of TES-OTf at -78°C. However, the TES ether protecting group of 10 proved to be too labile under these reaction conditions, and mixtures of 16a, 17, and 18a are obtained in reactions of 10 and 15. Disaccharide 17 arises via in situ cleavage of the TES ether of disaccharide 16a, while trisaccharide 18a results from a glycosidation of in situ generated 17 (or of 16a itself) with a second equivalent of 10. These problems were largely suppressed by using 3 with a 3-O-TBS ether protecting group as the glycosyl donor and 0.2 equiv of TES-OTf as the reaction promoter. Attempts to selectively glycosylate the C(3)-OH of diol acceptors 20 or 28 gave a 70:30 mixture of 21 and 22 in the reaction of 20 and a 43:27:30 mixture of regioisomeric trisaccharides 29 and 30 and tetrasaccharide 31 from the glycosidation reaction of 28. However, excellent results were obtained in the glycosidation of differentially protected disaccharide 34 using 1.5 equiv of 3 and 0.05 equiv of TBS-OTf in CH2-Cl2 at -78°C. The latter step is an important transformation in the recently reported synthesis of the landomycin A hexasaccharide unit.
How stable are epoxides? A novel synthesis of epothilone B
Martin, Harry J.,Drescher, Martina,Mulzer, Johann
, p. 581 - 583 (2007/10/03)
Remarkable stability of the oxirane function is displayed over a number of synthetic operations in a novel synthesis of the antitumor compound epothilone B. The cis-epoxide, generated very early by dihydroxylation of an (E)-olefin, was resistant to more than ten synthetic steps under a wide variety of reaction conditions. TBS = tert-butyldimethylsilyl.
Epothilone B and its derivatives as novel antitumor drugs: Total and partial synthesis and biological evaluation
Mulzer, Johann
, p. 205 - 238 (2007/10/03)
Microtubule stabilizing natural products, as exemplified by paclitaxel (taxolR), are being considered as novel drugs against malignant therapy resistent solid tumors. Among these compounds, epothilone B and some of its derivatives have emerged as particularly promising candidates for industrial development. The total and partial syntheses of these compounds are described in detail, and some of the most important recent results on their biological activity are discussed.
Synthesis of the northern hemisphere of epothilone A by a ten-membered ring closing metathesis reaction
Gerlach, Kai,Quitschalle, Monika,Kalesse, Markus
, p. 3553 - 3556 (2007/10/03)
The synthesis of the strained epothilone analog containing a ten- membered ring as well as the northern hemisphere of epothilone A is described. This approach, using the ring closing metathesis reaction, is a solution to the lack of stereocontrol observed
Improved synthesis of the northern hemisphere of epothilone A by a sharpless asymmetric dihydroxylation
Quitschalle, Monika,Kalesse, Markus
, p. 7765 - 7768 (2007/10/03)
An improved synthesis of the northern hemisphere of epothilone A is described. This approach utilizes the Sharpless asymmetric dihydroxylation of 5-hexen-2-one (allyl acetone) to generate the precursor for the Wittig reaction and the subsequent ring closing metathesis reaction (RCM). This strategy allows to generate precursor 13 as both enantiomers from ready available starting material in a very efficient manner.
The formal total synthesis of epothilone A
Kalesse, Markus,Quitschalle, Monika,Claus, Eckhard,Gerlach, Kai,Pahl, Axel,Meyer, Hartmut H.
, p. 2817 - 2823 (2007/10/03)
The formal total synthesis of epothilone A is described. The key steps in the synthesis of the northern hemisphere are a Z-selective ten-membered ring-closing metathesis reaction (RCM) and the diastereoselective alkylation at C8. Aldehyde 3 is formed by introduction of the thiazole moiety by a Wittig reaction and subsequent functional group transformation. An efficient route to keto acid 5 is described.
Synthesis of the C7-C17 segment of epothilones by a 10-membered ring closing metathesis reaction
Gerlach, Kai,Quitschalle, Monika,Kalesse, Markus
, p. 1108 - 1110 (2007/10/03)
The synthesis of the C7-C17 segment of epothilones employing a ring closing metathesis is described. Our approach utilizes the stereoselective methylation of the 10-membered lactone, generated by ring closing metathesis, for introducing the methyl group at C8 and provides an efficient access to strained epothilone derivatives, as well as to the C7-C17 segment of epothilones.
