123rd General Meeting of the KCS

Type Symposium
Area Current Trends in Organic Chemistry Ⅰ: Synthetic Methodology and Application
Room No. Room 301+302
Time THU 16:35-17:00
Code ORGN1-3
Subject α-Vinyl Enolization of β-Chlorovinyl Ketones: Pathway Discovery and Synthetic Utility
Authors Hun young Kim
College of Pharmacy, Chung-Ang University, Korea
Abstract In contrast to other α, β-unsaturated carbonyl compounds, a mild base-promoted α-vinyl enolization of β-chlorovinyl ketones allows the generation of unique intermediate species with nucleophilic or electrophilic reactivity. We have disclosed the synthetic utilities of β-chlorovinyl ketones based on a α-vinyl enolization strategy. However, one drawback in this strategy, especially in terms of reaction efficacy, is that the planar conformation of (Z)-β-chlorovinyl ketones displays a α-vinyl enolization significantly slower than that of (E)-β-chlorovinyl ketones. The tedious separation of (E)-β-chlorovinyl ketones from (Z)-β-chlorovinyl ketones and the lack of efficient synthetic methods to (E)-β-chlorovinyl ketones became the bottleneck in the synthetic utilization of β-chlorovinyl ketones via α-vinyl enolization. To improve efficacy of this strategy, we have explored two approaches: 1) microwave-assisted thermal α-vinyl enolization of β-chlorovinyl ketones, 2) (E)-selective Friedel-Crafts acylation of alkynes to β-chlorovinyl ketones by flow chemistry. In this talk, we will present an efficient synthetic transformation of stereoisomeric β-chlorovinyl ketones using ring-expansion, ring-opening, and cycloisomerization strategies with the discovery of a microwave-assisted thermal α-vinyl enolization of β-chlorovinyl ketones. The mixtures of (E/Z)-β-chlorovinyl ketones are directly employed without separation in this thermal α-vinyl enolization approach. Also, a flow chemistry approach will be introduced as a fast, high yielding, and stereoselective synthetic route to (E)-β-chlorovinyl ketones. The (E)/(Z) isomerization under the AlCl3-promoted Friedel-Crafts reaction conditions is prevented via the product segregation strategy using a flow chemistry system.
E-mail hunykim@cau.ac.kr