16666-80-1Relevant articles and documents
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
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.
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.
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
(+)- 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.
