Synthesis of Natural Polyacetylenes Bearing Furan Rings
摘要:
The first total syntheses of four new polyacetylene compounds have been achieved using convergent routes, which involved Cadiot-Chodkiewicz copper-catalyzed cross-coupling reactions to sp-sp centers as the key steps. 19-Furan-2-ylnonadeca-5,7-diynoic acid (1), 19-furan-2-ylnonadeca-5,7-diynoic acid methyl ester (2), 2-pentacosa-7,9-diynylfuran (3), and 21-furan-2-ylhenicosa-14,16-diyn-1-ol (4) were stable and could be readily identified, isolated, and purified in high overall yields.
Gold(I)-Catalyzed Intramolecular [4+3]-Cycloaddition Reactions with Furan Propargyl Esters as the Substrates: Carbenoid vs. Stabilized Allyl Cation
作者:Benjamin Gung、Ryan Conyers、Josh Wonser
DOI:10.1055/s-0033-1338946
日期:——
The tricyclic ring system with an oxabicyclo[3.2.1]octadiene and a fused six-membered ring was produced efficiently using the readily available propargyl esterfuran substrate in the presence of a Au(I) complex. The reaction involves a tandem 3,3-rearrangement of the propargyl ester followed by an intramolecular [4+3]-cycloaddition reaction. Both the primary ligand of the gold complex (N-heterocyclic
Amino Acid Derived Enamides: Synthesis and Aminopeptidase Activity
作者:Richard R. Cesati、Greg Dwyer、Reinaldo C. Jones、Megan P. Hayes、Padmaja Yalamanchili、David S. Casebier
DOI:10.1021/ol7025729
日期:2007.12.1
Recently developed copper-catalyzed coupling methodology has been applied to the Synthesis of amino acid derived enamides. Bond formation proved to be strongly influenced by protection strategy and vinyl iodide substitution while tolerant of limited side chain functionality. Assessment of aminopeptidase activity revealed a preference for (E)-1,2-disubstituted constructs.
A Domino Diels–Alder Approach toward the Tetracyclic Nicandrenone Framework
作者:Emily G. Mackay、Marck Nörret、Leon S.-M. Wong、Ignace Louis、Andrew L. Lawrence、Anthony C. Willis、Michael S. Sherburn
DOI:10.1021/acs.orglett.5b02412
日期:2015.11.20
The tetracarbocyclic framework of the nicandrenone natural products is formed in one step from a linear precursor via a domino intramolecular Diels-Alder/intramolecular furan Diels-Alder/aromatization sequence. The approach represents a new 0 -> ABCD strategy for the preparation of aromatic steroids.
Rhodium carbenoid mediated cyclizations of o-alkynyl-substituted .alpha.-diazoacetophenones
作者:Albert Padwa、Keith E. Krumpe、Jamal M. Kassir
DOI:10.1021/jo00044a032
日期:1992.8
o-Alkynyl-substituted alpha-diazoacetophenones undergo facile cyclization to indenone derivatives upon treatment with catalytic quantities of Rh(II) carboxylates. A variety of structural influences were encountered by varying the nature of the substituent group attached to the alkyne carbon atom. The cyclization reaction involves addition of a rhodium stabilized carbenoid onto the acetylenic pi-bond to generate a vinyl carbenoid. The vinyl carbenoid was found to undergo both CH and CC migration as well as delta-CH insertion into the alkyl backbone. Different catalysts were shown to result in significant variation in the product ratios for these reactions. Treatment of o-(5-(allyloxy)-1-pentynyl)-alpha-diazoacetophenone with rhodium(II) mandelate afforded 2-(2-propen-1-yl)-2-(1-oxo-1H-indenyl)-2,3,4,5-tetrahydrofuran in high yield. The formation of this compound involves initial formation of a vinyl carbenoid which reacts with the neighboring oxygen atom to give an oxonium ylide which subsequently undergoes a 2,3-sigmatropic rearrangement. When 2-ethynyl-alpha-diazoacetophenone is used, only products derived from 6-endo closure are observed. Substituted o-alkynyl alpha-diazoacetophenones give products derived from 5-exo cyclization. The mode of ring closure is controlled by both steric and electronic factors.
HARWOOD, LAURENCE M.;LEEMING, SARAH A.;ISAACS, NEIL S.;JONES, GERAINT;PIC+, TETRAHEDRON LETT., 29,(1988) N 39, C. 5017-5020
作者:HARWOOD, LAURENCE M.、LEEMING, SARAH A.、ISAACS, NEIL S.、JONES, GERAINT、PIC+