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Studies on the Carbon Zip Reaction of 2‐Oxocycloalkane‐1‐carbonitriles
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Titel: |
Studies on the Carbon Zip Reaction of 2‐Oxocycloalkane‐1‐carbonitriles |
In: | Helvetica Chimica Acta, 68, 1985, 7, S. 1986-1997 |
veröffentlicht: |
Wiley
|
Umfang: | 1986-1997 |
ISSN: |
1522-2675 0018-019X |
DOI: | 10.1002/hlca.19850680723 |
Zusammenfassung: | <jats:title>Abstract</jats:title><jats:p>As a part of continuing interest in the zip reaction, we present the results on a carbon ring‐enlargement reaction of activated ketones with a CN group as a charge stabilizer. Two series of (1‐cyano‐2‐oxocy‐cloalkyl)alkanoates were prepared from 8‐ and 12‐membered cyano‐ketones <jats:bold>1</jats:bold> and <jats:bold>2</jats:bold>, respectively, namely the propanoates <jats:bold>3</jats:bold> and <jats:bold>4</jats:bold>, the butanoates <jats:bold>6</jats:bold>, <jats:bold>8</jats:bold> and <jats:bold>9</jats:bold> as well as the pentanoates <jats:bold>12</jats:bold> and <jats:bold>15</jats:bold>. While treatment with <jats:italic>t</jats:italic>‐BuOK of the former two homologous esters resulted in both ring enlargement and competitive transesterification, the pentanoates <jats:bold>12</jats:bold> and <jats:bold>15</jats:bold> afforded mostly the diastereoisomeric mixtures of bicyclic alcohols <jats:bold>20a</jats:bold>–<jats:bold>c</jats:bold> and <jats:bold>31a</jats:bold>,<jats:bold>b</jats:bold>, respectively, which remained intact on further exposure to base. It was shown that – apart from the base used (<jats:italic>t</jats:italic>‐BuOK) <jats:italic>vs.</jats:italic> Li(i‐Pr)<jats:sub>2</jats:sub>N – the distribution of products was greatly influenced by the ring size of substrates. This is further illustrated by treatment of ketones <jats:bold>34</jats:bold> and <jats:bold>35</jats:bold> with <jats:italic>t</jats:italic>‐BuOK. While the former rearranged smoothly to diketone <jats:bold>36</jats:bold>, no reaction at all took place with the latter. The behavior of the substrates is discussed in terms of steric and energetic reasons.</jats:p> |
Format: | E-Article |
Quelle: | Wiley (CrossRef) |
Sprache: | Englisch |