The Reduction of Carbonyl Compounds with Dicyclopentylzinc: A New Example of Asymmetric Amplifying Autocatalysis
A previously unknown reduction of carbonyl compounds with dicyclopentylzinc is reported. Aldehydes react in mild conditions yielding corresponding primary alcohols and cyclopentene. Although cyclohexanone and acetophenone are inert to dicyclopentylzinc, a variety of heterocyclic ketones reacted read...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-12-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/24/23/17048 |
| Summary: | A previously unknown reduction of carbonyl compounds with dicyclopentylzinc is reported. Aldehydes react in mild conditions yielding corresponding primary alcohols and cyclopentene. Although cyclohexanone and acetophenone are inert to dicyclopentylzinc, a variety of heterocyclic ketones reacted readily, yielding reasonable to high yields of corresponding secondary alcohols. When the reaction was catalyzed with (–)-(1<i>R</i>,2<i>S</i>)-ephedrine, 3-acetylpyridine (<b>10</b>) resulted in a high yield of (<i>S</i>)-1-(pyridin-3-yl)ethanol (<b>19</b>) with >99% ee. 5-Acetyl-2-bromopyridine (<b>11</b>) also provided the corresponding optically active alcohol <b>20</b>, albeit with a much lower optical yield. When 10% of <b>19</b> with 92% ee was used as an autocatalyst, 55% yield of the same compound was obtained, with 95% ee and 96% ee in two independent experiments. A three-stage reaction sequence starting from “no chirality” reaction yielded <b>19</b> with 6% ee. Thus, amplifying autocatalysis was detected in the reaction of ketone <b>10</b> with dicylopentylzinc. |
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| ISSN: | 1661-6596 1422-0067 |