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Updated: Jun 5, 2025

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Synthesis of Consecutive All-Carbon Quaternary Centers via Three-Step Reactions
Xiaolei Han1, Huazhuo Ban1, Naoki Mori1
1Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
Abstract:
Consecutive all-carbon quaternary centers were synthesized in three steps from the corresponding ketones. The three reactions were (1) Knoevenagel condensation of ketone and malononitrile to afford dicyanoalkene, (2) 1,4-addition reaction of a Grignard reagent to dicyanoalkene, and (3) oxidative transformation of a malononitrile moiety to an ester, thioester, amide, and α-nitroketone. This method was applied to the synthesis of 17α-methyl steroids with a good yield and excellent diastereoselectivity. Moreover, three consecutive all-carbon quaternary centers were also synthesized.
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