19915-11-8Relevant articles and documents
Palladium(0)-catalyzed cyclization-carbonylation of 2,7-octadienyl acetate and homologues
Terakado, Masahiko,Murai, Kouya,Miyazawa, Masahiro,Yamamoto, Keiji
, p. 5705 - 5718 (1994)
The palladium(0)-catalyzed carbonylations, in acetic acid as a necessary solvent, of 2,7-octadienyl acetate and homologues via π-allylpalladium species were preceded by their intramolecular olefin insertion to form mixtures of cis/trans-2-vinylcyclopentylacetyl- and cis/trans-cyclohexylacetylpalladium intermediates, which undergo further the intramolecular (5-exo) Heck reaction to give bicyclo-[3.3.0] and [4.3.0] skeletons, respectively, except for one case affording trans-2-vinylcyclopentylacetic acid as a major product.
A synthetic approach to 5/5/6-polycyclic tetramate macrolactams of the discodermide type
Bodenschatz, Kevin,St?ckl, Julia,Winterer, Markus,Schobert, Rainer
, (2021/05/31)
A flexible synthetic route to the 16-membered tetramate-embedding macrocyclic scaffold present in various polycyclic tetramate macrolactams (PTMs) was developed which differs from the seminal synthesis of ikarugamycin by Boeckman Jr. in protecting groups and the order of connections. We also devised a short approach to various stereoisomers of the 5/5/6-tricarbocyclic motif found in discodermide and other PTMs, starting from the Weiss’ diketone.
The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
, p. 13695 - 13700 (2020/08/24)
The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
Stereoselective synthesis of (2E,4Z)-dienamides employing (triphenylphosphoranylidene)ketene
Pachali, Steffen,Hofmann, Christine,Rapp, Georg,Schobert, Rainer,Baro, Angelika,Frey, Wolfgang,Laschat, Sabine
supporting information; experimental part, p. 2828 - 2835 (2009/09/29)
The three-component reaction between ylide Ph3PCCO, amines and aldehydes is known to afford selectively (￡)-a,ssunsaturated amides. We applied a variant of this methodology to the preparation of (2B,4Z)-dienamides 11 utilizing the phosphonium s
A method for synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones with one-carbon ring expansion and its application to a formal synthesis of racemic 1-desoxyhypnophilin
Kashima, Hiroaki,Kawashima, Tadashi,Wakasugi, Daisuke,Satoh, Tsuyoshi
, p. 3953 - 3963 (2007/10/03)
A method for synthesis of 2-cyanobicyclo[3.3.0]oct-1-en-3-ones and 2-substituted bicyclo[3.3.0]oct-1-en-3-ones was developed by assembly of three components, cyclobutanones, chloromethyl p-tolyl sulfoxide, and nitriles, with one-carbon ring expansion of t
A novel synthesis of bicyclo[3.3.0]oct-1-en-3-ones from cyclobutanones through [chloro(p-tolylsulfinyl)methylidene]cyclobutanes with ring expansion
Kawashima, Tadashi,Kashima, Hiroaki,Wakasugi, Daisuke,Satoh, Tsuyoshi
, p. 3767 - 3770 (2007/10/03)
Treatment of [chloro(p-tolylsulfinyl)methylidene]cyclobutanes, which were synthesized from cyclobutanones and chloromethyl p-tolyl sulfoxide in three steps in high overall yields, with excess cyanomethyllithium gave enaminonitriles in high yields. Heating
Synthetic Applications in Radical/Radical Cationic Cascade Reactions
Rinderhagen, Heiko,Mattay, Jochen
, p. 851 - 874 (2007/10/03)
Oxidative photoinduced electron transfer (PET) reactions have been performed with various cyclic cyclopropyl(vinyl) silyl ethers bearing an olefinic or acetylenic side chain. The reactions result in bi- to tetracyclic ring systems via a fragmentation-radical/radical cationic addition reaction pathway with well defined ring juncture. The mode of cyclisation (endo/exo) can be partially controlled by addition of nucleophiles due to the suppression of radical cationic reaction pathways. Quantum chemical calculation of the cyclisation transition states underline the experimentally found selectivities. Additional mechanistic studies concerning the saturation step reveal that the final radical is saturated mostly by the solvent and traces of water in the solvent.
Syntheses and biological evaluation of vinblastine congeners.
Kuehne, Martin E,Bornmann, William G,Marko, Istvan,Qin, Yong,LeBoulluec, Karen L,Frasier, Deborah A,Xu, Feng,Mulamba, Tshilundu,Ensinger, Carol L,Borman, Linda S,Huot, Anne E,Exon, Christopher,Bizzarro, Fred T,Cheung, Julia B,Bane, Susan L
, p. 2120 - 2136 (2007/10/03)
Sixty-two congeners of vinblastine (VLB), primarily with modifications of the piperidine ring in the carbomethoxycleavamine moiety of the binary alkaloid, were synthesized and evaluated for cytotoxicity against murine L1210 leukemia and RCC-2 rat colon cancer cells, and for their ability to inhibit polymerization of microtubular protein at 10(7) M concentrations was found for L1210 inhibition by these compounds, with the most active 1000x as potent as vinblastine.
First example of an enone-alkene [2 + 2 + 2] photocycloaddition: 1,3-photocycloaddition of tetramethylethylene across 2,7-cyclooctadienone
Matlin, Albert R.,Lin, Susanne C.,Patel, Hiren R.,Chai, Minghui
, p. 303 - 305 (2008/03/11)
(equation presented) Irradiation of cyclooctadienone (1) in the presence of tetramethylethylene (TME) produces 9,10,10-tetramethyl-11-oxatricyclo[6.3.0.01,7]undec-2-ene (7) in 33% yield. This reaction is the first example of a 1,3-cycloaddition of an alkene across an enone system. This novel cycloaddition suggests that there is substantial interaction between the carbonyl carbon and the β-enone carbon in the triplet excited state of 1.
Bicyclo[3.3.0]octanone Formation by Fe(III) mediated ring expansion- transannular cyclisation reactions of cyclopropyl ethers
Booker-Milburn,Dainty, Richard F.
, p. 5097 - 5100 (2007/10/03)
Substituted bicyclo[5.1.0]octene derivatives undergo facile Fe(III) mediated radical ring expansion-transannular cyclisation reactions to give the corresponding bicyclo[3.3.0]octanones.
