186641-79-2Relevant academic research and scientific papers
Formal total synthesis of mandelalide A
Yamini,Reddy, K Mahender,Krishna, A Shiva,Lakshmi,Ghosh, Subhash
, (2019/03/23)
Abstract: In this article the formal total synthesis of mandelalide A has been described in details. The highly convergent and flexible strategy developed for mandelalide A involved the construction of key building blocks ent-9 and 7, and their assembly t
Cobalt versus Osmium: Control of Both trans and cis Selectivity in Construction of the EFG Rings of Pectenotoxin 4
Roushanbakhti, Ahria,Liu, Yifan,Winship, Paul C. M.,Tucker, Michael J.,Akhtar, Wasim M.,Walter, Daryl S.,Wrigley, Gail,Donohoe, Timothy J.
supporting information, p. 14883 - 14887 (2017/10/24)
Catalytic oxidative cyclisation reactions have been employed for the synthesis of the E and F rings of the complex natural product target pectenotoxin 4. The choice of metal catalyst (cobalt- or osmium-based) allowed for the formation of THF rings with either trans or cis stereoselectivity. Fragment union using a modified Julia reaction then enabled the synthesis of an advanced synthetic intermediate containing the EF and G rings of the target.
Synthesis of proposed aglycone of mandelalide A
Reddy, Karla Mahender,Yamini, Vanipenta,Singarapu, Kiran K.,Ghosh, Subhash
supporting information, p. 2658 - 2660 (2014/06/09)
A highly convergent synthesis of the proposed mandelalide A aglycone is reported. The cornerstones of the synthetic strategy include the following: E-selective intramolecular Heck cyclization, Masamune-Roush olefination, Stork-Zhao-Wittig olefination, mod
Highly stereocontrolled total synthesis of β-d-mannosyl phosphomycoketide: A natural product from mycobacterium tuberculosis
Li, Nan-Sheng,Scharf, Louise,Adams, Erin J.,Piccirilli, Joseph A.
, p. 5970 - 5986 (2013/07/26)
β-d-Mannosyl phosphomycoketide (C32-MPM), a naturally occurring glycolipid found in the cell walls of Mycobacterium tuberculosis, acts as a potent antigen to activate T-cells upon presentation by CD1c protein. The lipid portion of C32-MPM contains a C32-mycoketide, consisting of a saturated oligoisoprenoid chain with five chiral methyl branches. Here we develop several stereocontrolled approaches to assemble the oligoisoprenoid chain with high stereopurity (>96%) using Julia-Kocienski olefinations followed by diimide reduction. By careful choice of olefination sites, we could derive all chirality from a single commercial compound, methyl (2S)-3-hydroxy-2-methylpropionate (>99% ee). Our approach is the first highly stereocontrolled method to prepare C32-MPM molecule with >96% stereopurity from a single >99% ee starting material. We anticipate that our methods will facilitate the highly stereocontrolled synthesis of a variety of other natural products containing chiral oligoisoprenoid-like chains, including vitamins, phytol, insect pheromones, and archaeal lipids.
Synthesis of stereopure acyclic 1,5-dimethylalkane chirons: Building blocks of highly methyl-branched natural products
Li, Nan-Sheng,Piccirilli, Joseph A.
, p. 9633 - 9641 (2013/10/22)
An efficient synthetic method towards stereopure acyclic 1,5-dimethylalkane building blocks from methyl (2R)-3-hydroxy-2-methylpropionate (R)-1 (>99% ee) and methyl (2S)-3-hydroxy-2-methylpropionate (S)-1 (>99% ee) through a series of chemical transformat
(-)-lytophilippine a: Synthesis of a C1-C18 building block
Gille, Annika,Hiersemann, Martin
supporting information; experimental part, p. 5258 - 5261 (2011/02/24)
The convergent enantioselective synthesis of a protected C1-C18 building block for the total synthesis of (-)-lytophilippine A was achieved. A catalytic asymmetric Gosteli-Claisen rearrangement and an Evans aldol reaction served as key C/C-connecting transformations during the assembling of the C1-C7 subunit (10 steps from 4, 29%). The synthesis of the C8-C18 segment was achieved utilizing d-galactose as inexpensive ex-chiral-pool starting material (15 steps, 15%). The merger of the subunits was accomplished by a remarkably efficient sequence consisting of esterification and ring-closing metathesis (five steps, 56%).
Anti-AIDS agents 81. design, synthesis, and structure-activity relationship study of betulinic acid and moronic acid derivatives as potent HIV maturation inhibitors
Qian, Keduo,Kuo, Reen-Yun,Chen, Chin-Ho,Huang, Li,Morris-Natschke, Susan L.,Lee, Kuo-Hsiung
experimental part, p. 3133 - 3141 (2010/09/18)
In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3′ dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC50: 0.0006 μM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.
Anti-AIDS agents 73: Structure-activity relationship study and asymmetric synthesis of 3-O-monomethylsuccinyl-betulinic acid derivatives
Qian, Keduo,Nakagawa-Goto, Kyoko,Yu, Donglei,Morris-Natschke, Susan L.,Nitz, Theodore J.,Kilgore, Nicole,Allaway, Graham P.,Lee, Kuo-Hsiung
, p. 6553 - 6557 (2008/03/18)
3-O-3′(or 2′)-Methylsuccinyl-betulinic acid (MSB) derivatives were separated by using recycle HPLC. The structures of four isomers were assigned by NMR and asymmetric synthesis. 3-O-3′S-Methylsuccinyl-betulinic acid (3′S-MSB, 4) exhibited potent anti-HIV
Catalytic asymmetric synthesis of mycocerosic acid
Ter Horst, Bjorn,Feringa, Ben L.,Minnaard, Adriaan J.
, p. 489 - 491 (2007/10/03)
The first catalytic asymmetric total synthesis of mycocerosic acid was achieved via the application of iterative enantioselective 1,4-addition reactions and allows for the efficient construction of 1,3-polymethyl arrays with full stereocontrol; further exemplified by the synthesis of tetramethyl-decanoic acid, a component of the preen-gland wax of the graylag goose, Anser anser. The Royal Society of Chemistry.
Total synthesis of rutamycin B and oligomycin C
Panek,Jain
, p. 2747 - 2756 (2007/10/03)
The asymmetric synthesis of the macrolide antibiotics (+)-rutamycin B (1) and (+)-oligomycin C (2) is described. The approach relied on the synthesis and coupling of the individual spiroketal fragments 3a and 3b with the C1-C17 polyproprionate fragment 4. The preparation of the spiroketal fragments was achieved using chiral (E)-crotylsilane bond construction methodology, which allowed the introduction of the stereogenic centers prior to spiroketalization. The present work details the synthesis of the C19-C28 and C29-C34 subunits as well as their convergent assembly through an alkylation reaction of the lithiated N,N-dimethylhydrazones 6 and 8 to afford the individual linear spiroketal intermediates 5a and 5b, respectively. After functional group adjustment, these advanced intermediates were cyclized to their respective spiroketal-coupling partners 40 and 41. The requisite polypropionate fragment was assembled in a convergent manner using asymmetric crotylation methodology for the introduction of six of the nine-stereogenic centers. The use of three consecutive crotylation reactions was used for the construction of the C3-C12 subunit 32. A Mukaiyama-type aldol reaction of 35 with the chiral α-methyl aldehyde 39 was used for the introduction of the C12-C13 stereocenters. This anti aldol finished the construction of the C3-C17 advanced intermediate 36. A two-carbon homologation completed the construction of the polypropionate fragment 38. The completion of the synthesis of the two macrolide antibiotics was accomplished by the union of two principal fragments that was achieved with an intermolecular palladium-(0) catalyzed cross-coupling reaction between the terminal vinylstannanes of the individual spiroketals 3a and 3b and the polypropionate fragment 4. The individual carboxylic acids 46 and 47 were cyclized to their respective macrocyclic lactones 48 and 49 under Yamaguchi reaction conditions. Deprotection of these macrolides completed the synthesis of the rutamycin B and oligomycin C.
