1730-25-2Relevant articles and documents
Electronic Control of Stereoselectivity. 11. Long-Range Modulation of Stereoselection in Diels-Alder Cycloadditions of N-Methyltriazolinedione to Aryl-Substituted 9-Butadienylidenebenzonorbornenes
Paquette, Leo A.,Klinger, Francois
, p. 272 - 275 (1982)
Three 9-butadienylidenebenzonorbornenes (4a-c) have been synthesized and their ability to enter into Diels-Alder reaction examined.Although these substances are unreactive to a host of dienophiles, tetracyanoethylene enters into addition with 4b and 4c.However, these reactions do not allow for examination of the stereoselectivity question.When recourse was made to the more reactive N-methyltriazolinedione reagent, adducts 9 and 10 were produced in the following syn/anti ratios: 4a, 49:51; 4b, 24:76; 4c, 24:76.The chemical shifts of the N-methyl groups in the urazole segments of these adducts proved quite divergent and conducive to reliable structural assignment.The results are interpreted in terms of zwitterion intervention, with charge delocalization into the aromatic ring where this is feasible (the tetrafluoro example excluded).Because of this long-range homoaromatic stabilization, closure of the second C-N bond from the anti direction is kinetically favored.
Synthesis of trans,trans,cis-fused tetracyclic skeleton via radical domino cyclization
Furuta, Miyu,Hanaya, Kengo,Sugai, Takeshi,Shoji, Mitsuru
, p. 2316 - 2322 (2017)
Limonoids are characterized by a polycyclic structure and show a wide variety of bioactivities. In particular, mesendanin L, 12-hydroxyamoorastatone, and meliatoosenin F have unique structures containing a trans-A/B/C and cis-C/D-fused tetracyclic skeleton. We synthesized the core structure of these limonoids via Mn(OAc)3 and Cu(OAc)2-mediated radical domino cyclization of an acyclic tetraene precursor having a terminal β-keto ester. To the best of our knowledge, this is the first example of the radical-mediated construction of a 6/6/6/5-membered tetracyclic skeleton.
Characterization of typical potent odorants in raw and cooked Toona sinensis (A. Juss.) M. Roem. by instrumental-sensory analysis techniques
Yang, Wenxi,Cadwallader, Keith R.,Liu, Yuping,Huang, Mingquan,Sun, Baoguo
, p. 153 - 163 (2019/01/26)
Toona sinensis (A. Juss.) M. Roem. (TS) possesses a unique and pleasant flavor and is consumed as a popular seasonal vegetable in certain parts of eastern and southeastern Asia. The potent odorants in raw and cooked TS were identified by combined sensory and instrumental analysis techniques, including sensory descriptive aroma profiling and two complimentary volatile isolation methods combined with gas chromatography-olfactometry (GC-O) techniques. Highly volatile odorants were determined by static headspace dilution analysis (SHDA)-GC-O, while those of intermediate- and semi-volatility were determined by solvent-assisted flavor evaporation-aroma extract dilution analysis (SAFE-AEDA). Among the numerous odorants identified by SHDA and SAFE-AEDA, (E,E)-bis-(1-propenyl) disulfide was found to be predominant in both raw and cooked TS. In agreement with results of sensory descriptive analysis, hexanal, (Z)-3-hexenal, (E)-2-hexenal and (Z)-3-hexen-1-ol contributed green, grassy and leafy aroma notes; while hydrogen sulfide, methyl thiirane, (E,E)-bis-(1-propenyl) disulfide and (E,Z)-bis-(1-propenyl) disulfide contributed pungent, sulfurous and alliaceous notes in TS.
A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins
Boukattaya, Fatma,Caillé, Julien,Ammar, Houcine,Rouzier, Florian,Boeda, Fabien,Pearson-Long, Morwenna S. M.,Bertus, Philippe
, p. 906 - 916 (2016/03/12)
A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.
FLAME-RETARDANT PROCESSED RESIN OBTAINED WITH A REACTIVE FLAME RETARDANT
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Page/Page column, (2014/01/18)
A reactive flame retardant which imparts excellent flame retardancy to resins even when added in a small amount and can be prevented from bleeding out; and a flame-retardant processed resin obtained with the flame retardant. The reactive flame retardant is, for example, an organophosphorus cyclic compound which is represented by the following general formula (I) and has at least one unsaturated group at ends of R 1 to R 4 . The flame-retardant processed resin is obtained by solidifying a resin composition containing this organophosphorus cyclic compound and then reacting the compound by heating or irradiation with a radiation.
Dynamic kinetic asymmetric cross-benzoin additions of β-stereogenic α-keto esters
Goodman, C. Guy,Johnson, Jeffrey S.
supporting information, p. 14698 - 14701 (2014/12/11)
The dynamic kinetic resolution of β-halo α-keto esters via an asymmetric cross-benzoin reaction is described. A chiral N-heterocyclic carbene catalyzes the umpolung addition of aldehydes to racemic α-keto esters. The resulting fully substituted β-halo glycolic ester products are obtained with high levels of enantio- and diastereocontrol. The high chemoselectivity observed is a result of greater electrophilicity of the α-keto ester toward the Breslow intermediate. The reaction products are shown to undergo highly diastereoselective substrate-controlled reduction to give highly functionalized stereotriads.
PROCESS FOR IXABEPILONE, AND INTERMEDIATES THEREOF
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Paragraph 0234, (2014/09/29)
The present invention relates to a novel process of making ixabepilone, ixabepilone derivatives and analogues, and intermediates thereof.
Development of a scalable process for DG-041, a potent EP3 receptor antagonist, via tandem heck reactions
Zegar, Siead,Tokar, Christopher,Enache, Livia A.,Rajagopol, Venkat,Zeller, Wayne,O'Connell, Matthew,Singh, Jasbir,Muellner, Frank W.,Zembower, David E.
, p. 747 - 753 (2012/12/29)
DG-041 is a small molecule antagonist of the EP3 receptor for prostaglandin E2 that is in clinical development for treatment of peripheral artery disease (PAD). Originally produced using a six-step synthetic procedure, process optimization led to development of a four-step sequence that is readily scalable. The key step in the optimized sequence contains two sequential Heck reactions, involving an intramolecular Heck cyclization followed by an intermolecular Heck coupling, performed in one pot to produce a highly substituted indole core.
Stereoselective polycyclisations of allyl and enyne silanes: Evidence for bicyclo[3.2.0]hept-1(7)ene structure
Oba, Gabriel,Moreira, Georges,Manuel, Georges,Koenig, Max
, p. 324 - 330 (2007/10/03)
The intramolecular copper(I)-catalyzed [2 + 2]-photocycloaddition of diphenyldiallysilane (1) (or tetraallylsilane (4)) led to sila-3-bicyclo[3.2.0]heptane (3) (or to spiro analogous 6) in the cis (or cis-cis) configuration whereas the α,ω-diiodide (2) obtained by cyclozirconation of 1 (or from the homologous tetraiodide 5) followed by addition of n-BuLi, produced the sila-3-bicyclo[3.2.0]heptane (3) (or to the spiro analogous 6) in the trans (or trans-trans configuration). The same cyclozirconation reaction, starting from the hetero enyne 7, selectively led to the highly strained silacyclobutene moiety 15 which represents the first stable hetero bicyclo[3.2.0]hept-1(7)ene skeleton, hypothetical intermediate in methathesis reactions.
First total synthesis of natural 6-epiplakortolide e.
Jung, Mankil,Ham, Jungyeob,Song, Jueun
, p. 2763 - 2765 (2007/10/03)
[reaction: see text] Natural 6-epiplakortolide E was first synthesized from readily available 1-bromo-10-phenyldecane in 10 steps by using singlet oxygen-mediated Diels-Alder reaction to form cyclic peroxide followed by a directed iodolactonization to give the peroxylactone core.
