Chiral CO<sub>2</sub>-Synthons via Catalytic Asymmetric Hetero-Diels−Alder Reactions of Ketomalonate and Dienes
作者:Sulan Yao、Mark Roberson、Frank Reichel、Rita G. Hazell、Karl Anker Jørgensen
DOI:10.1021/jo990696i
日期:1999.9.1
A catalytic enantioselective approach for the formation of chiral CO(2)-synthons is presented. The described methodology is based on the reaction of dienes with diethyl ketomalonate using C(2)-symmetric bisoxazolines as the chiral ligands and copper(II) and zinc(II) as the Lewis acids. For cyclic dienes the reaction proceeds in good yield and with up to 93% ee for 1,3-cyclohexadiene, while for cyclopentadiene
Cyclohexenyl nucleosides: Synthesis of cis-4-(9H-purin-9-yl)-2-cyclohexenylcarbinols
作者:Michael J. Konkel、Robert Vince
DOI:10.1016/0040-4020(95)00926-4
日期:1996.1
Syntheses of the title compounds were accomplished in 6–7 steps, starting from cyclohexadiene and chlorosulphonyl isocyanate. The key step of the strategy involves a palladium coupling of cyclohexenyl dicarbonate 8 with either 6-chloropurine or 2-amino-6-chloropurine.