HETEROCYCLES

■ CATALYTIC ASYMMETRIC INTERMOLECULAR C–H INSERTION OF 1,4-CYCLOHEXADIENE WITH α-ALKYL-α-DIAZOESTERS USING CHIRAL DIRHODIUM(II) CARBOXYLATES

Takayuki Goto, Tomohiro Onozuka, Yuhei Kosaka, Masahiro Anada, Koji Takeda, and Shunichi Hashimoto*

*Laboratory of Synthetic and Industrial Chemistry, Graduate School of Life Science, Division of Life Science, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12, Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan

Abstract

The first example of dirhodium(II) complex-catalyzed asymmetric intermolecular C–H insertion with α-alkyl-α-diazoesters is described. The reaction of 1,4-cyclohexadiene with 2,4-dimethyl-3-pentyl α-alkyl-α-diazoacetates under catalysis by dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate], Rh2(S-PTTL)4, or dirhodium(II) tetrakis[N-tetrafluorophthaloyl-(S)-tert-leucinate], Rh2(S-TFPTTL)4, gave the corresponding C–H insertion products with enantioselectivities of up to 86% ee, albeit in low to modest yields.