128571-74-4Relevant academic research and scientific papers
Chiral γ-(tetrahydropyranyloxy)allylstannane: a new chiral reagent for the asymmetric synthesis of syn 1,2-diols
Kadota, Isao,Kobayashi, Katsumi,Okano, Hiroshi,Asao, Naoki,Yamamoto, Yoshinori
, p. 615 - 623 (2007/10/02)
(2R,3S)-3-Allyloxy-3,4,5,6-tetrahydro-2H-pyran-2-methanol was prepared in high yield from tri-O-acetyl-D-glucal, an easily available and cheap chiral source.The hydroxy group was protected as the t-butyldiphenylsilyl ether, and the allyl group was converted to the corresponding allyl stannane via formation of allyl carbanion and subsequent trapping with tributylstannyl chloride.The γ-alkoxy allyl stannane 1 bearing the (2R,3S)-2--3,4,5,6-tetrahydro-2H-pyran-3-yloxy auxiliary at the allyl terminus was prepared by this procedure.The reaction of 1 with aldehydes in the presence of AlCl3*OEt2 or AlCl3 gave the corresponding syn adducts 2 with high diastereoselectivities; the ratio of syn/anti > 97:3.The diastereomeric excess of the syn adducts 2, that is, the ratio 2/(2 + the (S,S) isomer of 2), varied from 85 to 94percent.Removal of the protecting group of 2 gave the (R,R) diols 3.The high diastereo- and enantioselectivity in the formation of the (R,R) isomer is accounted for by an anti S'E transition state 18. allylstannane / γ-alkoxyallylstannane / asymmetric synthesis / syn-1,2-diol / Lewis acid / allylstannane-aldehyde condensation / γ-(tetrahydropyranyloxy)allylstannane / anti S'E
Asymmetric Synthesis of Syn 1,2-Diols via the Reaction of Aldehydes with Chiral γ-(Tetrahydropyranyloxy)allylstannanes
Yamamoto, Yoshinori,Kobayashi, Katsumi,Okano, Hiroshi,Kadota, Isao
, p. 7003 - 7005 (2007/10/02)
Asymmetric synthesis of syn 1,2-diols 3 has been accomplished via the reaction of the chiral γ-alkoxy-substituted allylstannane 1 with aldehydes in the presence of AlCl3 or AlCl3*OEt2, followed by a five-step operation to remove the chiral auxiliary.
METHOXYCHLORINATION AND DIMETHOXYLATION OF ALKENES. THE REACTIONS OF SUBSTITUTED STYRENES WITH PHENYLSELENENYL CHLORIDE IN METHANOL
Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Bartoli, Donatella
, p. 2261 - 2272 (2007/10/02)
The addition of PhSeCl to α- and β-substituted styrenes in methanol is regio- and stereospecific and affords the products of methoxyselenenylation.These compounds further react with PhSeCl to give the deselenenylation products.In the case of α-substituted styrenes, 1-methoxy, 2-chloroalkanes are produced, whereas with β-substituted styrenes the major reaction products are the 1,2-dimethoxyalkanes and the 2,2-dimethoxyalkanes in which phenyl migration has occured.It is shown that these reactions proceed through the intermediate formation of the alkyl phenylselenium dichlorides, PhCR(OMe)CHR1SeCl2Ph, which evolve with different mechanisms depending on the structure of the starting alkenes.
Photochemical Electron-transfer Reaction between Aromatic Olefins and Metal Ions. Dependence of the Reaction Course on the Structure of the Olefins
Kojima, Masanobu,Sakuragi, Hirochika,Tokumaru, Katsumi
, p. 521 - 524 (2007/10/02)
To investigate the photochemical electron transfer from aromatic olefins to copper(II) or iron(III) ions, a series of substituted styrenes (1) was irradiated in the presence of copper(II) or iron(II) salts in methanol, which gave dimethoxylated monomers (2) and one or more of three types of dimethoxylated dimers .The formation of these products are reasonably attributed to the participation of hte cation radicals of the olefins generated by electron transfer from excited olefins to the methal ions.Substituents on the substrates are found to govern the reaction products.
