160238-46-0Relevant academic research and scientific papers
Polyoxygenated Tertiary Alcohols: A Kiyooka Approach
Lücke, Daniel,Kalesse, Markus
, p. 10080 - 10083 (2019/07/18)
A Kiyooka aldol approach for the stereoselective synthesis of tertiary alcohols is presented. This approach allows for the incorporation of different substituents at all three remaining positions at the chiral center bearing the tertiary alcohol. To demon
PROCESS FOR THE PREPARATION OF MACROCYCLIC KETONE ANALOGS OF HALICHONDRIN B
-
, (2019/11/19)
The present invention discloses a novel process for the preparation of macrocyclic ketone analogs of halichondrin B or pharmaceutically acceptable salts thereof and to novel intermediates which are produced during the course of carrying out the novel process.
Rifamycin Biosynthetic Congeners: Isolation and Total Synthesis of Rifsaliniketal and Total Synthesis of Salinisporamycin and Saliniketals A and B
Feng, Yu,Liu, Jun,Carrasco, Yazmin P.,MacMillan, John B.,De Brabander, Jef K.
, p. 7130 - 7142 (2016/07/06)
We describe the isolation, structure elucidation, and total synthesis of the novel marine natural product rifsaliniketal and the total synthesis of the structurally related variants salinisporamycin and saliniketals A and B. Rifsaliniketal was previously proposed, but not observed, as a diverted metabolite from a biosynthetic precursor to rifamycin S. Decarboxylation of rifamycin provides salinisporamycin, which upon truncation with loss of the naphthoquinone ring leads to saliniketals. Our synthetic strategy hinged upon a Pt(II)-catalyzed cycloisomerization of an alkynediol to set the dioxabicyclo[3.2.1]octane ring system and a fragmentation of an intermediate dihydropyranone to forge a stereochemically defined (E,Z)-dienamide unit. Multiple routes were explored to assemble fragments with high stereocontrol, an exercise that provided additional insights into acyclic stereocontrol during stereochemically complex fragment-assembly processes. The resulting 11-14 step synthesis of saliniketals then enabled us to explore strategies for the synthesis and coupling of highly substituted naphthoquinones or the corresponding naphthalene fragments. Whereas direct coupling with naphthoquinone fragments proved unsuccessful, both amidation and C-N bond formation tactics with the more electron-rich naphthalene congeners provided an efficient means to complete the first total synthesis of rifsaliniketal and salinisporamycin.
Directed hydrogenations and an Ireland-Claisen rearrangement linked to Evans-Tishchenko chemistry: The highly efficient total synthesis of the marine cyclodepsipeptide doliculide
Chen, Tao,Altmann, Karl-Heinz
, p. 8403 - 8407 (2015/06/02)
Two new convergent total syntheses have been developed for the cytotoxic, actin microfilament-stabilizing marine cyclodepsipeptide doliculide (1). A key strategic element of both routes is the establishment of the central stereogenic center of the characteristic polydeoxypropionate stereotriad by means of a hydroxyl-directed catalytic hydrogenation of a trisubstituted double bond. The requisite olefin substrates were obtained through a modified Suzuki-Miyaura coupling or through Ireland-Claisen rearrangement of a propionate ester, respectively; the latter was the direct result of a highly selective Evans-Tishchenko reduction of a hydroxy ketone that had been obtained in a stereoselective Paterson aldol reaction. Doliculide (1) was finally obtained in a total number of 17 or 15 (14) linear steps, respectively, which represents a substantial improvement over previous syntheses of this highly bioactive natural product.
Concise diastereoselective synthesis of calcaripeptide C via asymmetric transfer hydrogenation/Pd-induced chiral allenylzinc as a key reaction
Kumaraswamy, Gullapalli,Narayanarao, Vykunthapu,Raju, Ragam
, p. 8487 - 8494 (2015/08/06)
Synthesis of the natural product calcaripeptide C derived from the fungal metabolite mycelium KF525 of Calcarisporium sp. has been achieved. This complementary approach avoids the use of a stoichiometric amount of chiral auxiliary reagents as commonly used to generate enantioenriched advanced precursors. The enantioselective synthesis of calcaripeptide C is remarkable in that using catalytic reactions sets the two stereogenic centers efficiently with good levels of enantioselectivity. Further diversification of the calcaripeptide C structures is possible by employing a complementary catalytic enantioenriched Ru-catalyst.
Synthetic Studies toward the C32-C46 Segment of Hemicalide. Assignment of the Relative Configuration of the C36-C42 Subunit
Specklin, Simon,Boissonnat, Guillaume,Lecourt, Camille,Sorin, Geoffroy,Lannou, Marie-Isabelle,Ardisson, Janick,Sautel, Fran?ois,Massiot, Georges,Meyer, Christophe,Cossy, Janine
supporting information, p. 2446 - 2449 (2015/05/27)
The synthesis of five diastereomeric model compounds incorporating the C32-C46 segment of the antitumor marine natural product hemicalide has been achieved through a convergent approach relying on the 1,4-addition of an alkenyl boronate to an α,β-unsaturated δ-lactone followed by α-hydroxylation of an enolate and a Julia-Kocienski olefination. Comparison of the 1H and 13C NMR data of the model compounds with those of hemicalide enabled the assignment of the relative configuration of the C36-C42 subunit. (Chemical Equation Presented).
Synthesis of spongistatin 2 employing a new route to the EF fragment
Kraus, Helmut,Francais, Antoine,O'Brien, Matthew,Frost, James,Dieguez-Vazquez, Alejandro,Polara, Alessandra,Baricordi, Nikla,Horan, Richard,Hsu, Day-Shin,Tsunoda, Takashi,Ley, Steven V.
, p. 1989 - 1994 (2013/06/05)
An improved route to the EF fragment of the spongistatins has been developed and employed in a synthesis of spongistatin 2. The C48-C51 diene side chain, which lacks the chlorine substituent present in spongistatin 1, presented some compatibility issues d
Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
supporting information, p. 13284 - 13287,4 (2012/12/12)
Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
Palladium-catalyzed cross-coupling of unactivated alkenes with acrylates: Application to the synthesis of the C13-C21 fragment of palmerolide A
Wen, Zhen-Kang,Xu, Yun-He,Loh, Teck-Peng
supporting information, p. 13284 - 13287 (2013/01/15)
Diene to meet: A palladium-catalyzed cross-coupling reaction between alkyl-substituted olefins and acrylates gives the corresponding butadienes in moderate yield and stereoselectivity. This atom-economical reaction, which forms C sp 2-C sp 2 bonds, tolerates a wide range of allylic and homoallylic alcohols, and acrylates (see scheme; TIPS =triisopropylsilyl). The methodology was applied to the synthesis of the C13-C21 fragment of palmerolide A.
Synthesis of (Z)-Trisubstituted olefins by decarboxylative Grob-Type fragmentations: Epothilone D, discodermolide, and peloruside A
Prantz, Kathrin,Mulzer, Johann
scheme or table, p. 485 - 506 (2010/06/14)
Methyl-branched (Z)-trisubstituted olefins are found in many polyketides with interesting biological activity, such as epothilone D (1), discodermolide (3), and peloruside A (2). Despite the employment of numerous different strategies, this motif has often been the weak point in total synthesis. Thus, we present a novel hydroxideinduced Grob-type fragmentation as an easy access to trisubstituted olefins. In our case, β-mesyloxy δ-lactones with three stereogenic centers were chosen whose fragmentation underlies a high stereoelectronic control. Major challenges in the syntheses were the instailation of quaternary stereocenters, achieved by enzymatic desymmetrization of meso-diesters and by aluminiumpromoted stereoselective rearrangement of chiral epoxides, respectively. Different aldol strategies were developed for the formation of the fragmentation precursors. Additionally a short survey about nucleophilic additions to aldehydes with quaternary α-centers is presented.
