Systematic Studies using 2-(1-Adamantylethynyl)pyrimidine-5-carbaldehyde as a Starting Material in Soai’s Asymmetric Autocatalysis
✍ Scribed by Mark Busch; Martin Schlageter; Daniel Weingand; Timo Gehring
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 303 KB
- Volume
- 15
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
Herein, we present a new substrate for the Soai reaction, which has an adamantylethynyl residue (1 g) and exhibits asymmetric autocatalysis, yielding products with enantiomeric excesses above 99 %. For the first time, all reactions were performed on a parallel synthesizer system to ensure identical reaction conditions. A detailed systematic study of reaction parameters was performed and we report the highest enhancements of enantiomeric excess reported so far in the Soai reaction in one reaction cycle (7.2→94.1 % ee or 3.1→92.1 % ee). Our results led to a set of reaction parameters that yield reproducible results. Therefore, our new starting material 1 g is suitable for systematic and mechanistic studies on this remarkable reaction. A series of experiments designed to quantify the amplification of enantiomeric excess demonstrated that the reaction can be used in principle as a tool for the detection of low enantiomeric excesses: under definite conditions, an unknown low enantiomeric excess (0.1–7 %) was amplified to a detectable one. A back calculation to the original value offers a new method for the determination of small enantiomeric excesses.