220018-27-9Relevant academic research and scientific papers
Progress toward a Convergent, Asymmetric Synthesis of Jervine
De Jesús Cruz, Pedro,Johnson, Jeffrey S.,Zavesky, Blane P.
, (2020/04/30)
Progress toward a convergent approach for the enantioselective synthesis of the Veratrum alkaloid jervine is presented. The two requisite fragments were stereoselectively and efficiently fashioned from economical and readily available reagents. Key reactions include (a) a highly diastereoselective Ireland-Claisen rearrangement to establish the necessary cis-relationship between the amine and methyl group on the tetrahydrofuran E-ring; (b) a diastereoselective selenoetherification reaction that enabled the assembly of the D/E oxaspiro[4.5]decene in the needed configuration; and (c) an enzymatic desymmetrization of an abundant achiral diol en route to a key four-carbon building block as a practical alternative to a protected Roche ester reduction.
Synthetic studies towards an advanced precursor of the jatrophane diterpene Pl-4
Fürst, Rita,Lentsch, Christoph,Rinner, Uwe
, p. 357 - 367 (2014/02/14)
Jatrophane diterpenes, isolated from members of the Euphorbiaceae plant family, constitute a class of biologically and structurally intriguing natural products. Herein, different strategies for the preparation of an advanced intermediate towards the total synthesis of the jatrophane diterpene Pl-4 are described. Key strategies for the elaboration of the jatrophane precursors include hydrometalation and radical reactions. Georg Thieme Verlag KG Stuttgart · New York.
Synthesis of an advanced intermediate of the jatrophane diterpene Pl-4: A dibromide coupling approach
Fuerst, Rita,Rinner, Uwe
, p. 8748 - 8758 (2013/09/24)
The preparation of an advanced intermediate toward the synthesis of the jatrophane diterpene Pl-4 is described. The key step is a regioselective chelation-controlled lithiation of the (Z)-configured bromide in the corresponding vinyl dibromide precursor. The method outlined within this Article is suitable for the facile access of sterically hindered internal vinyl halides for further coupling reactions.
The leiodolide B puzzle
Larivee, Alexandre,Unger, John B.,Thomas, Mikael,Wirtz, Conny,Dubost, Christophe,Handa, Shinya,Fuerstner, Alois
supporting information; experimental part, p. 304 - 309 (2011/02/28)
Out of options? Even though a systematic approach was chosen, which led to a set of four diastereomeric macrolides modeled around the proposed structure of leiodolide B (see picture), the puzzle concerning the stereostructure of this cytotoxic metabolite derived from a deep-sea sponge still remains unsolved. Copyright
Synthesis of the C10-C32 core structure of spirangien A
Lorenz, Michael,Kalesse, Markus
supporting information; experimental part, p. 4371 - 4374 (2009/06/06)
(Chemical Equation Presented) The synthesis of the C10-C32 core structure of spirangien A is reported. The pivotal aldol coupling between both key intermediates provides a synthetic challenge in the synthesis of this complex natural product.
Enantioselective total synthesis of epothilones A and B using multifunctional asymmetric catalysis
Sawada, Daisuke,Kanai, Motomu,Shibasaki, Masakatsu
, p. 10521 - 10532 (2007/10/03)
An enantioselective total synthesis of epothilones A (1) and B (2) using multifunctional asymmetric catalysis such as a cyanosilylation of an aldehyde, an aldol reaction of an unmodified ketone with an aldehyde, and a protonation in the conjugate addition of a thiol to an α,β-unsaturated thioester has been achieved. We divided 1 and 2 into fragment A, fragment B, and fragment C. A catalytic asymmetric synthesis of fragments A and B was accomplished using a catalytic asymmetric cyanosilylation as a key step. An enantiocontrolled synthesis of fragment C was achieved in two ways. One is the use of a direct catalytic asymmetric aldol reaction of an unmodified ketone with an aldehyde as a key step, and the other utilizes a catalytic asymmetric protonation in the conjugate addition of a thiol to an α,β-unsaturated thioester as a key step. Suzuki cross-coupling of fragment A with fragment C followed by Yamaguchi lactonization as key steps led to an enantiocontrolled synthesis of epothilone A (1). On the other hand, Suzuki cross-coupling of fragment B with fragment C followed by Yamaguchi lactonization accomplished an enantiocontrolled synthesis of epothilone B (2).
Approaches to a synthesis of galbonolide B
Smith, Peter M.,Thomas, Eric J.
, p. 3541 - 3556 (2007/10/03)
An approach to the C(7)-C(15) fragment of galbonolide B 2 has been completed in which the diene fragment 51 was assembled from (R)-3-tert-butyldimethylsilyloxypentan-2-one 29 by conversion into the unsaturated ester 30, acylation of the sulfone 47 using this ester, reductive desulfurisation, methylenation using a Wittig reaction and deprotection. Following model studies, the aldehyde 62, prepared by oxidation of the alcohol 51, was converted into a mixture of the epimeric alcohols 63 and these were converted into the di(methylene)tridecadienoic acid 65 using a phosphine catalysed Ireland-Claisen rearrangement. Sharpless epoxidations of the alcohol 67 using either L-(+)- or D-(-)-diethyl tartrate were highly stereoselective and gave the epoxides 68 and 69 which were clearly distinguishable. Model studies using the heptadiene monoepoxide 70 led to a synthesis of the monoprotected dihydroxy aldehyde 76 so establishing a protocol for the introduction into the vicinal diol of the galbonolides. Finally, aldol addition of tert-butyl acetate to the aldehyde 78 followed by selective protection, deprotection and cyclisation completed a synthesis of the macrolide 85.
