Download or read book Studies Toward Total Synthesis of Amphidinolide A written by Yan Yu and published by . This book was released on 2001 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthetic Studies Toward the Total Synthesis of Amphidinolide B1 written by Wei Zhang and published by . This book was released on 2006 with total page 660 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies Toward the Synthesis of the Amphidinolides written by Brian J. Myers and published by . This book was released on 2000 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies Toward the Total Synthesis of Amphidinolide C written by Robert H. Bates and published by . This book was released on 2009 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amphidinolide C is one of the most biologically potent members of the amphidinolide family of natural products. Detailed in this thesis are studies toward the total synthesis of this complex macrolide. Three distinct syntheses of the C(1)-C(9) fragment are described. The first generation synthesis involves a diastereoselective chelate-controlled [3+2]-annulation reaction to form the C(3)-C(6) trans tetrahydrofuran. The second generation approach takes advantage of the C(4) methyl substituent to induce diastereoselectivity in an intramolecular hetero-Michael cyclization to form the same tetrahydrofuran. The third generation incorporates a non-chelate-controlled [3+2]-annulation reaction to afford the cis tetrahydrofuran product, followed by a base-promoted epimerization to the desired trans tetrahydrofuran. This route was accomplished in fewer steps than the first generation synthesis. Also described are stereoselective syntheses of the C(18)-C(34) C(10)-C(26) fragments of amphidinolide C, and the C(10)-C(29) fragment of amphidinolide F, a closely related natural product. Finally, a clear plan for the completion of the total synthesis of amphidinolide C is presented.

Download or read book Studies Towards the Total Synthesis of Amphidinolides O and P written by Matthew A. Foster and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toward a Total Synthesis of amphidinolide P and Related Studies written by Jens-Martin Herold and published by . This book was released on 2008 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finally, novel palladium-catalyzed conjugate additions of organozinc reagents to alpha,beta-unsaturated aldehydes are discussed. This methodology can be diastereoselective and can be used for the selective preparation of (E)-silyl enol ethers. The palladium-catalyzed reaction is also compared to its copper-catalyzed counterpart.

Download or read book Studies Towards the Total Synthesis of the Amphidinolide C Family of Natural Products written by Andrew P. Osnowski and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthetic Studies Toward the Total Synthesis of the Hydrophobic Domain of the Amphidinolide B type Isomers written by Hugo M. Eng and published by . This book was released on 1994 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Total Synthesis of amphidinolide W and Efforts Toward Total Synthesis of lasonolide A written by Gangli Gong and published by . This book was released on 2005 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Towards the Total Synthesis of Amphidinolide F written by Daniel A. Mills and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Part I Total Synthesis of Marine Macrolide Amphidinolide F and Synthetic Studies Toward Amphidinolide C written by Subham Mahapatra and published by . This book was released on 2013 with total page 639 pages. Available in PDF, EPUB and Kindle. Book excerpt: More than 30 members of the diverse amphidinolide family of biologically active macrolides have been isolated over last three decades. From this family, amphidinolides C and F stand among the most complex and densely functionalized affiliates. Recently, we have accomplished the first total synthesis of amphidinolide F. The all-carbon framework of amphidinolide C has been synthesized. During endeavor toward the total syntheses of amphidinolides F / C, we have uncovered a "hidden symmetry element" present in the northern and southern domains of amphidinolides F / C. The southern C1-C and northern C1-C25 tetrahydrofuran segments were derived from a common intermediate. A scalable silver-catalyzed isomerization / cyclization on propargyl-benzoate / diol furnished the common intermediate in multigram quantity. The common intermediate provided access to over half of carbon backbone of the macrocycle as well as majority of stereochemistry present in amphidinolides F / C. Two strategically different techniques have been developed for the C9-C11 diene preparation. A metal-catalyst free Weinreb amide-vinyl lithium coupling / methylenation sequence furnished the diene motif. Alternately, diastereoselective addition of a dienyl iodide derived 2-lithio-1,3-diene species to an [alpha]-oxy aldehyde installed the C9-C11 diene and secured the C8 stereochemistry in single operation. The dienyl iodide was prepared via a regioselective hydrostannylation on an enyne. A challenging alkylation between an [alpha]-branched sulfone and an [alpha]-silyloxy iodide generated the all-carbon frameworks of amphidinolides F / C. An efficient oxidative desulfurization incorporated the carbonyl moiety at C15. The protecting group on C18 alcohol was found to have significant effect on the sulfone-iodide alkylation / oxidative desulfurization sequence. Installation of chelating ethoxyethyl ether on C18 alcohol helped the successful incorporation of C15 ketone and solved the deprotection problem in advanced stage of synthesis. A detailed analytical and computational study on proline sulfonamide-catalyzed aldol reactions has been performed. The pKa value of a proline sulfonamide catalyst was determined experimentally via NMR titration technique. Computational study revealed the origin of enhanced stereoselectivity by proline sulfonamide catalysts over parent proline. The non-classical hydrogen bonding interactions were found to be responsible for improved diastereoselectivity.

Download or read book Part I written by Liang Lu and published by . This book was released on 2010 with total page 786 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structural architecture present in marine toxin azaspiracid - 20 stereocenters, 9 rings, 3 separated spirocenters - has attracted considerable synthetic attention. Our efforts toward the synthesis of azaspiracid have led to the completion of both C1-C26 northern and C27-C40 southern halves. Herein, the synthesis of southern FGHI ring system is described. The key steps included an Andrus anti-aldol coupling to furnish the C32, C33 stereocenters, an acid-catalyzed ketalization to furnish FG rings, and a Yb(OTf)3-mediated spiroaminal formation to generate I ring. The first total synthesis of cytotoxic macrolides amphidinolide B1 and the proposed structure of amphidinolide B2 have been accomplished. The key developed protocols include a metal catalyst-free sequence for the synthesis of the diene subunit, a non-chelation-controlled aldol coupling to install the C18 stereocenter, an efficient macrocyclization of the 26-membered lactone ring, and the incorporation of the labile allylic epoxide moiety. The unique structure of the highly substituted diene functionality represents significant synthetic challenges. A Wittig / HWE reaction sequence yielded the C13-C15 diene moiety in good yield in excellent diastereoselectivity. Subsequent Sharpless epoxidation and Red-Al-mediated regionselective epoxide opening gave the C16 tertiary alcohol. The protecting groups on C21 were discovered to have significant effects on the aldol reaction between C9-C18 aldehyde and C19-C25 methyl ketone. Although chelating groups such as PMB, Bn afforded 18S isomer as a single diastereomer, the removal of these groups has proven problematic. Non-chelating silyl group generated 18R isomer in 8:1 dr at -100°C, while the 18S stereomer was obtained at -40°C in 1.2:1 dr. A spontaneous intramolecular Wadsworth-Emmons olefination established the 26-membered macrocycle. The oxidation and in situ elimination of a selenide moiety proceeded smoothly in the presence of free alcohols using TMSOOTMS. The first total synthesis of amphidinolide B1 and the proposed structure of amphidinolide B2 were accomplished in 29 linear steps. Additionally, We discovered that the initially proposed structure of amphidinolide B2 was incorrect.

Download or read book Progress Towards the Total Synthesis of Amphidinolide E written by Andrew Frederick Nolting and published by . This book was released on 2006 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Studies Toward Synthesis of Lasonolide A Total Synthesis and Structural Determination of Dispongin A and B written by Kailas Bhalchandra Sawant and published by . This book was released on 2007 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Progress Towards the Total Synthesis of Amphidinolide C written by Nicholas A. Morra and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A second generation catalyst for the Mukaiyama oxidative cyclization for the formation of trans-THF rings is described. Co(nmp)2, displays increased stability to the reaction conditions, resulting in lower catalyst loadings, lower reaction temperatures, and significantly higher purity and yields of the products. Three procedures have been developed with this new water-soluble catalyst that greatly simplifies the post-reaction purification, making this procedure the premier method of forming trans-THF rings. This new catalyst has been applied towards the total synthesis of the potently bioactive macrocycle, Amphidinolide C. Herein we report the successful synthesis of several fragments of the natural product, and our attempts at coupling them to complete the synthesis. The C(1)-C(9) was achieved via two routes, both utilizing the highly effective oxidation catalyst Co(nmp)2 to form the methyl substituted trans-THF ring. Synthetic highlights include a regioselective Shi epoxidation, and the design and introduction of a novel Lewis acid (BF2OBn×OEt2) to facilitate a stereoselective reductive epoxide opening. The C(18)-C(34) fragment was also achieved via two routes, culminating in both the shortest (11 steps) and highest yielding (26% overall yield) approaches to this segment. Synthetic highlights of this fragment include a selective methylation of a diyne, and a highly selective alkynylation of a THF aldehyde, achieving excellent dr (>20:1) without the addition of an external chiral compound. Advanced intermediates comprising the entirety of the carbon backbone of the molecule have been synthesized, which in theory could complete the total synthesis in as few as two bond forming steps.

Download or read book Towards the Total Synthesis of Amphidinolide C written by Guang Yang and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Total Synthesis of Amphidinolide E and Amphidinolide E Stereoisomers written by Porino J. Va and published by . This book was released on 2007 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed in the following thesis are stereocontrolled syntheses of four amphidinolide E stereoisomers: amphidinolide E, 2- epi -amphidinolide E, 19- epi -amphidinolide E, and 2- epi -19- epi -amphidinolide E. Preliminary studies targeting amphidinolide E led to the inadvertent syntheses of 2- epi -amphidinolide E and 2- epi -19- epi -amphidinolide E due to an unexpected and highly selective C2 inversion during the modified Yamaguchi esterification step involving the (2 S, 3 S) (CO) 3 Fe-complexed dienoic acid. Ultimately, this C2 inversion phenomenon was discovered and use of the (2 S, 3 R) (CO) 3 Fe-complexed dienoic acid enabled the syntheses of amphidinolide E and 19- epi -amphidinolide E. Featured in the synthetic route is the synthesis of the tetrahydrofuran core of amphidinolide E through a highly diastereoselective [3+2] annulation reaction. Also noteworthy, are the synthesis of the 19-membered macrocycle via a ring closing metathesis reaction and use of the (CO) 3 Fe-unit as a diene protecting group to enable an efficient esterification of the hindered alcohol substrate.