title: A Highly diastereoselective synthesis of (1R)-(+)-camphor-based chiral allenes and their asymmetric hydroboration-oxidation reactions.
abstract: Synthesis of camphor derived chiral allenes and their hydroboration-oxidation reactions are described. Reaction of (1R)-(+)-camphor with alkynyllithium followed by the reduction of the resulted propargyl alcohol derivatives using AlH3 furnished chiral allenes 2a-g in excellent yields with high diastereoselectivity. Reduction of the propargyl alcohols with aluminum hydride proceeded through selective intermolecular anti-addition of hydride ion. The stereochemistry of the chiral allenes 2 was assigned based on lanthanide shift studies and chemical correlations. Diastereoselectivity was observed in the hydroboration-oxidation of 2 which produced a mixture of (E,R) and (E,S) stereoisomers in a ratio of 6:1 to 18:1.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan 300, Republic of China.
authors.forename: Shang-Cheng
authors.initials: SC
authors.lastname: Hung
authors.forename: Yen-Fang
authors.initials: YF
authors.lastname: Wen
authors.forename: Jia-Wen
authors.initials: JW
authors.lastname: Chang
authors.forename: Chun-Chen
authors.initials: CC
authors.lastname: Liao
authors.forename: Biing-Jiun
authors.initials: BJ
authors.lastname: Uang