Gallium Tribromide Catalyzed Coupling Reaction of Alkenyl Ethers with Ketene Silyl Acetals
作者:Yoshihiro Nishimoto、Hiroki Ueda、Makoto Yasuda、Akio Baba
DOI:10.1002/anie.201203778
日期:2012.8.6
couple: The α‐alkenylation of esters was accomplished by GaBr3‐catalyzed coupling between alkenyl ethers and ketene silyl acetals. In this reaction system, various alkenyl ethers, including those with vinyl and substituted alkenyl groups, were applicable, and the scope of applicable ketene silyl acetals was sufficiently broad. The mechanism is also discussed.
Unusual Tandem Oxidative C–C Bond Cleavage and Acetalization of Chalcone Epoxides in the Presence of Iodine in Methanol
作者:Shriniwas Samant、Balaso Jadhav
DOI:10.1055/s-0033-1339134
日期:——
of chalcone epoxides is observed where chalcone epoxides on heating with iodine in methanol leads to α,α-dimethoxyacetophenones, through C–C bondcleavage followed by acetalization of the formyl group. The process occurs through ring opening of the chalcone epoxide by methanol to form β-methoxy alcohol, cleavage of the C–C bond in the latter to form α-ketoaldehyde, and acetalization of the formyl group
Catalytic enantioselective reactions. Part 16. Oxazaborolidine-catalyzed asymmetric borane reduction of α-keto acetals
作者:Byung Tae Cho、Yu Sung Chun
DOI:10.1039/a903335a
日期:——
Asymmetricreductions of α-keto acetals using various oxazaborolidines and borane reagents as catalyst and the hydride source, respectively, were compared. The reduction catalyzed by Corey’s CBS reagents with N-phenylamine–borane reagents provided α-hydroxy acetals with very high enantioselectivities for most aromatic analogues.
Madelung; Oberwegner, Justus Liebigs Annalen der Chemie, 1931, vol. 490, p. 201,210, 225
作者:Madelung、Oberwegner
DOI:——
日期:——
Asymmetric reduction of α-keto acetals with potassium 9-O-(1,2-isopropylidene-5-deoxy-D-xylofuranosyl)-9-boratabicyclo[3.3.1]nonane. Enantioselective synthesis of α-hydroxy acetals with high optical purities
作者:Byung Tae Cho、Yu Sung Chun
DOI:10.1016/0957-4166(94)80142-8
日期:1994.7
Asymmetric reduction of alpha-keto acetals with a chiral borohydride, potassiun 9-O-(1,2-isopropylidene-5-deoxy-alpha-D-xylofuranosyl)-9-boratabicyclo[3.3.1]nonane in THF at -78 degrees C provided the corresponding alpha-hydroxy acetals with 87-99% ee.