926905-41-1Relevant articles and documents
Syntheses of (R)-(+)-cibenzoline and analogues via catalytic enantioselective cyclopropanation using (S)-phenylalanine-derived disulfonamide
Miura, Tsuyoshi,Murakami, Yasuoki,Imai, Nobuyuki
, p. 3067 - 3069 (2006)
Cyclopropanation of 3,3-diaryl-2-propen-1-ols 1 with Et2Zn and CH2I2 proceeded in the presence of a catalytic amount of (S)-2-(methanesulfonyl)amino-1-(p-toluenesulfonyl)amino-3-phenylpropane 2 to afford the corresponding
1-[(E)-2-arylethenyl]-2,2-diphenylcyclopropanes: Kinetics and mechanism of rearrangement to cyclopentenes
Mulzer, Johann,Huisgen, Rolf,Arion, Vladimir,Sustmann, Reiner
, p. 1359 - 1388 (2011/10/09)
Kinetic measurements for the thermal rearrangement of 2,2-diphenyl-1-[(E)- styryl]cyclopropane (22a) to 3,4,4-triphenylcyclopent-1-ene (23a) in decalin furnished ΔHρm{{-{isom}^{ne }}}$=31.0±1.2kcal mol-1 and ΔSρm{{-{isom}^{ne }}}$=-6. 0±2.6e.u. The lowering of ΔHa‰ by 20kcal mol-1, compared with the rearrangement of the vinylcyclopropane parent, is ascribed to the stabilization of a transition structure (TS) with allylic diradical character. The racemization of (+)-(S)-22a proceeds with ΔHρm{{-{rac}^{ne }}}$=28.2±0.8kcal mol -1 and ΔSρm{{-{rac}^{ne }}}$=-5±2e.u., and is at 150° 106 times faster than the rearrangement. Seven further 1-(2-arylethenyl)-2,2-diphenylcyclopropanes 22, (E)- and (Z)-isomers, were synthesized and characterized. The (E)-compounds showed only modest substituent influence in their krac (at 119.4°) and kisom (at 159.3°) values. The lack of solvent dependence of rate opposes charge separation in the TS, but a linear relation of log krac with log p.r.f., i.e., partial rate factors of radical phenylations of ArH, agrees with a diradical TS. The ring-opening of the preponderant s-trans-conformation of 22 gives rise to the 1-exo-phenylallyl radical 26 that bears the diphenylethyl radical in 3-exo-position, and is responsible for racemization. The 1-exo-3-endo-substituted allylic diradical 27 arises from the minor s-gauche-conformation of 22 and is capable of closing the three- or the five-membered ring, 22 or 23, respectively. The discussion centers on the question whether the allylic diradical is an intermediate or merely a TS. Quantum-chemical calculations by Houk etal. (1997) for the parent vinylcyclopropane reveal the lack of an intermediate. Can the conjugation of the allylic diradical with three Ph groups carve the well of an intermediate? Copyright
The use of 1,2-O-isopropylidene-α-d-xylofuranose as a chiral auxiliary in asymmetric cyclopropanation reactions
Vega-Perez, Jose M.,Perinan, Ignacio,Iglesias-Guerra, Fernando
experimental part, p. 1065 - 1072 (2009/09/30)
The stereoselective synthesis of cyclopropylmethylidene acetals derived from 1,2-O-isopropylidene-d-xylofuranose, as a chiral auxiliary, is described. The Simmons-Smith cyclopropanation reaction of the corresponding alkenylidene derivatives with CH2
Convenient preparation of optically active cibenzoline and analogues from 3,3-diaryl-2-propen-1-ols
Koyata, Naka,Miura, Tsuyoshi,Akaiwa, Yoko,Sasaki, Hisashi,Sato, Rie,Nagai, Takuya,Fujimori, Hirohisa,Noguchi, Takuya,Kirihara, Masayuki,Imai, Nobuyuki
experimental part, p. 2065 - 2071 (2010/01/16)
(R)-(+)-Cibenzoline (95% ee) was synthesized in two steps from (+)-2,2-diphenylcyclopropylmethanol 3a (98% ee), which was oxidized with IBX in DMSO, followed by treatment with ethylenediamine in the presence of I2 and K2CO3/sub
