16666-80-1Relevant academic research and scientific papers
Sequential application of stereoselective syn-oxidation methodologies to natural product synthesis: A potentially biomimetic approach to the C12-C21 bistetrahydrofuran region of monensin
McDonald, Frank E.,Schultz, Colleen C.
, p. 16435 - 16448 (1997)
The preparation of an all-Z-triene corresponding to an acyclic premonensin triene is described. In analogy to the Townsend syn- oxidative cyclization hypothesis for natural product biosynthesis, a sequence of regioselective and enantioselective syn-dihydr
Two new convenient syntheses of 14C-squalene from turbinaric acid
Philippe, Nicolas,Rivron, Luc,De Bruin, Béatrice,Schofield, Joseph,Roy, Sébastien
, p. 878 - 884 (2018)
Carbon-14 labeled (6E,10E,14E,18E)-2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene, also known as squalene, was synthesized as a tool for pharmacokinetic studies. Two simple and efficient labeling approaches were developed to give [2-14/
A new [2 + 2] functionalization of C60 with alkyl-substituted 1,3- butadienes: A mechanistic approach. Stereochemistry and isotope effects
Vassilikogiannakis, Georgios,Chronakis, Nikos,Orfanopoulos, Michael
, p. 9911 - 9920 (1998)
The stereochemistry and secondary isotope effects of the [2 + 2] photocycloaddition of trans,trans- (7), cis,cis- (8), and cis,trans-2,4- hexadiene (9), 2,5-dimethyl-2,4-hexadiene (1), and its deuterated analogues 1-d1, 1-d6, and tra
ELECTRON TRANSFER IN THE REACTION OF BENZALDEHYDE WITH A NONSTABILIZED YLIDE
Yamataka, Hiroshi,Nagareda, Katsushi,Hanafusa, Terukiyo,Nagase, Shigeru
, p. 7187 - 7190 (1989)
The Wittig reaction of benzaldehyde with isopropylidenetriphenylphosphorane was sugested to proceed via a single electron transfer mechanism on the basis of 14C kinetic isotope effect and substituent effect experiments.
A new method for generating organosilanones
Zemlyansky, N. N.,Borisova, I. V.,Shestakova, A. K.,Ustynyuk, Yu. A.,Chernyshev, E. A.
, p. 2126 - 2127 (1994)
A new method for the generation of organosilanones by the reaction of betains, R3P+-CR1R2-SiR3R4-S-, with (Et3Sn)2O was suggested. - Key words: organosilicon-phosphorus betaine; organosilan
Competitive Reactions of Alkylidenetriphenylphosphoranes and Methylsulfinyl Carbanion with 3-Methylenespiroundeca-1,4-diene
Murray, Diane F.
, p. 4860 - 4864 (1983)
Treatment of 3-methylenespiroundeca-1,4-diene (3) with methylenetriphenylphosphorane in Me2SO provides 3-ethylidenespiroundeca-1,4-diene (4) as the major product in 33percent yield.The expected cyclopropane product dispirotrideca-4,12-diene is obtained in only 1-2percent yield.Control experiments show that 4 arises from the reaction of the methylsulfinyl carbanion.Indeed, when 3 is treated with a Me2SO solution of the methylsulfinyl carbanion, multiple additions of the methylsulfinyl carbanion occur.The competition between the Wittig reagent and the methylsulfinyl carbanion in reaction with 3 can be shifted to favor the formation of cyclopropane products by increasing the nucleophilicity of the Wittig reagent by alkyl substitution at the carbanionic center.Thus, treatment of 3 with ethylidenetriphenylphophorane in Me2SO gives 4 and 1-methyldispirotrideca-4,12-diene in yields of 28percent and 17percent, repectively, and reaction of 3 with isopropylidenetriphenylphosphorane in Me2SO gives 1,1-dimethyldispirotrideca-4,12-diene in 64percent yield and less than a 1percent yield of 4.
Catalytic Systems for Production of 1-Hexene by Selective Ethylene Trimerization
Afanas’ev, V. V.,Bespalova, N. B.,Cheredilin, D. N.,Kozlova, G. A.,Senin, A. A.,Sheloumov, A. M.
, p. 55 - 68 (2020/02/25)
Abstract: New chromium complexes with diphosphine ligands have been obtained by the reaction of chromium(III) hexahydrate and diphosphines in acetone. The structure of chromium(III) complex 4 containing water molecule and 1,2-bis(diphenylphosphino)benzene as ligands and that of two chromium(III) complexes (12 and 13) with 1,2-bis(diphenylphosphino)benzene ligands containing alkenyl substituents in the ortho-position of one of the phenyl groups at the phosphorous atom have been determined using X-ray diffraction analysis. The catalytic properties of the obtained complexes in the composition of catalytic systems for ethylene trimerization have been studied. It has been shown that the obtained series of catalytic systems manifests high activity in the process of ethylene trimerization to 1-hexene, with the process selectivity exceeding 94%. The highest value of productivity amongst known selective catalytic systems for trimerization was achieved using a chromium complex 13 bearing the 2-methylprop-1-enyl group at the ortho-position of one of the phenyl groups. The influence of temperature, pressure, the nature of the solvent and the composition of the catalytic system on the parameters of the process of ethylene trimerization to form 1-hexene has been determined.
Annulated and bridged tetrahydrofurans from alkenoxyl radical cyclization
Schur, Christine,Kelm, Harald,Gottwald, Thomas,Ludwig, Arne,Kneuer, Rainer,Hartung, Jens
supporting information, p. 8288 - 8307 (2015/01/09)
4-Pentenoxyl radicals sharing two or more carbon atoms with a cycloalkane cyclize in a predictable manner stereoselectively and regioselectively to afford in solutions of bromotrichloromethane cycloalkyl-fused or -bridged 2-bromomethyltetrahydrofurans in up to 95% yield. Stereoselectivity in alkenoxyl radical ring closures arises from cumulative steric effects. The substituent positioned the closest to the alkene carbon, which is being attacked by the oxygen radical, exerts the strongest stereodirecting effect. This principal inductor guides 5-exo-cyclization 2,3-trans- or 2,4-cis-selectively. The substituent located further from the attacked π-bond is the secondary inductor. A secondary inductor in the relative trans-configuration enhances stereodifferentiation by the primary inductor; a cis-configured secondary inductor decreases this effect. A secondary inductor is not able to overrule the guiding effect of a similar sized primary inductor. Intramolecular 4-pentenoxyl radical additions to a cyclohexene-bound exo-methylene group or to endocyclic double bonds proceed cis-specifically, as exemplified by synthesis of a diastereomerically pure bromobicyclo[2.2.1]heptyl-annulated tetrahydrofuran from the verbenylethyloxyl radical. According to theory, the experimental 2,3-cis-specificity in alkoxyl radical cyclization to an endocyclic π-bond arises from strain associated with the 2,3-trans-ring closure. This journal is
Photocycloaddition of biscyclopropyl alkenes to C60: An unprecedented approach toward cis-1 tricyclic-fused fullerenes
Tzirakis, Manolis D.,Alberti, Mariza N.,Orfanopoulos, Michael
, p. 3364 - 3367 (2011/09/12)
A novel, simple, and entirely regioselective tandem cycloaddition of biscyclopropyl-substituted alkenes to [60]fullerene has been revealed. This reaction affords cis-1 tricyclic-fused organofullerenes bearing the hitherto elusive 5-4-5 fused tricyclic ring system.
(+)- And (-)-mutisianthol: First total synthesis, absolute configuration, and antitumor activity
Bianco, Graziela G.,Ferraz, Helena M. C.,Costas, Arinice M.,Costa-Lotufo, Leticia V.,Pessoa, Claudia,De Moraes, Manoel O.,Schreins, Marcus G.,Pfaltz, Andreas,Silva Jr., Luiz F.
supporting information; experimental part, p. 2561 - 2566 (2009/09/25)
The first synthesis of the natural product (+)-mutisianthol was accomplished in 11 steps and in 21% overall yield from 2-methylanisole. The synthesis of its enantiomer was also performed in a similar overall yield. The absolute configuration of the sesquiterpene (+)-mutisianthol was assigned as (15,37?). Key steps in the route are the asymmetric hydrogenation of a nonfunctionalized olefin using chiral iridium catalysts and the ring contraction of 1,2-dihydronaphthalenes using thallium(III) or iodine(III). The target molecules show moderate activity against the human tumor cell lines SF-295, HCT-8, and MDA-MB-435.
