One-carbon ring-expansion of 2-substituted cyclohexanones via lithium- and magnesium β-oxido carbenoid rearrangement: a new synthesis of 2,7-disubstituted and 2,2,7-trisubstituted cycloheptanones |
| |
Authors: | Tsuyoshi Satoh Shu Tanaka Naoyuki Asakawa |
| |
Institution: | Department of Chemistry, Faculty of Science, Tokyo University of Science, Ichigaya-Funagawara-Machi, Shinjuku-ku, Tokyo 162-0826, Japan |
| |
Abstract: | Lithium α-sulfinyl carbanion of 1-chloroethyl p-tolyl sulfoxide was reacted with 2-substituted cyclohexanones to afford adducts in good yields. The adducts were treated with LDA or t-BuMgCl to give lithium or magnesium alkoxides, which were treated with t-BuLi or i-PrMgCl to afford one-carbon ring-expanded 2,7-disubstituted cycloheptanones through β-oxido carbenoids. Interestingly, 2,3-disubstituted cycloheptanones were obtained in a trace amount or were not obtained at all. The enolate intermediates of this reaction were found to be able to get trapped with electrophiles to give 2,2,7-trisubstituted cycloheptanones in moderate to good yields. This method is very useful for the synthesis of 2,7-disubstituted cycloheptanones and 2,2,7-trisubstituted cycloheptanones from 2-substituted cyclohexanones in only two steps. |
| |
Keywords: | Sulfoxide β-Oxido carbenoid rearrangement One-carbon ring-expansion 2 7-Disubstituted cycloheptanone 2 2 7-Trisubstituted cycloheptanone |
本文献已被 ScienceDirect 等数据库收录! |
|