Zink, Markus Peter;
Wolf, Hans Richard;
Müller, Ernst Peter;
Schweizer, Wolfhard Bernd;
Jeger, Oskar
Photochemische Reaktionen. 83. Mitteilung. Verbindungen der 3,4‐Dihydrojonon‐Reihe als Modelle zur Photochemie γ, δ‐ bzw. δ, ϵ‐ungesättigter Ketone und Aldehyde
You can manage bookmarks using lists, please log in to your user account for this.
Media type:
E-Article
Title:
Photochemische Reaktionen. 83. Mitteilung. Verbindungen der 3,4‐Dihydrojonon‐Reihe als Modelle zur Photochemie γ, δ‐ bzw. δ, ϵ‐ungesättigter Ketone und Aldehyde
Contributor:
Zink, Markus Peter;
Wolf, Hans Richard;
Müller, Ernst Peter;
Schweizer, Wolfhard Bernd;
Jeger, Oskar
Description:
<jats:p><jats:bold>Compounds of the 3,4‐dihydro‐ionone series as models for the photochemistry of γ, δ‐ and δ,ϵ‐ unsaturated ketones and aldehydes</jats:bold>.</jats:p><jats:p>The photochemistry of γ, δ‐ and δ,ϵ‐unsaturated carbonyl compounds of the dihydro‐ionone series has been studied, with special attention to the investigation of oxetane formation <jats:italic>versus</jats:italic> hydrogen abstraction.</jats:p><jats:p>UV.‐irradiation of the dihydro‐β‐ionone compounds with structure <jats:bold>A</jats:bold> (<jats:bold>1</jats:bold>, <jats:bold>7</jats:bold>, <jats:bold>14</jats:bold>, <jats:bold>18</jats:bold>, <jats:bold>24</jats:bold>, <jats:bold>29</jats:bold>) led to isomeric ethers with structures <jats:bold>B</jats:bold> (<jats:bold>2</jats:bold>, <jats:bold>8</jats:bold>, <jats:bold>15</jats:bold>, <jats:bold>19</jats:bold>, <jats:bold>25</jats:bold>, <jats:bold>30</jats:bold>), <jats:bold>C</jats:bold> (<jats:bold>3</jats:bold>, <jats:bold>9</jats:bold>, <jats:bold>16</jats:bold>, <jats:bold>20</jats:bold>, <jats:bold>26</jats:bold>, <jats:bold>31</jats:bold>) and <jats:bold>D</jats:bold> (<jats:bold>4</jats:bold>, <jats:bold>21</jats:bold>, <jats:bold>27</jats:bold>), isomeric bicyclic alcohols with structure <jats:bold>E</jats:bold> (<jats:bold>5</jats:bold>, <jats:bold>10</jats:bold>, <jats:bold>17</jats:bold>, <jats:bold>22</jats:bold>, <jats:bold>28</jats:bold>), and photoreduction products with structure <jats:bold>F</jats:bold> (<jats:bold>6</jats:bold>, <jats:bold>11</jats:bold>, <jats:bold>12</jats:bold>, <jats:bold>13</jats:bold>). Photolysis of dihydro‐γ‐ionone (<jats:bold>32</jats:bold>) gave a complex mixture containing fragmentation product <jats:bold>35</jats:bold>, hydrocarbon <jats:bold>36</jats:bold>, β‐ambrinol (<jats:bold>34</jats:bold>), oxetane <jats:bold>33</jats:bold>, as well as dihydro‐β‐ionone (<jats:bold>1</jats:bold>) and three of its photoproducts (<jats:bold>2</jats:bold>, <jats:bold>3</jats:bold>, <jats:bold>5</jats:bold>). The dihydro‐α‐ionone compounds <jats:bold>37</jats:bold> and <jats:bold>40</jats:bold> gave mixtures of fragmentation products and the oxetanes <jats:bold>38</jats:bold> and <jats:bold>41</jats:bold>. Irradiation of the side‐chain homologues <jats:bold>42</jats:bold> and <jats:bold>45</jats:bold> yielded <jats:bold>43</jats:bold>, which photo‐cyclizes to <jats:bold>44</jats:bold>. In contrast, <jats:bold>3</jats:bold>, <jats:bold>4</jats:bold>‐dihydro‐3′,4′‐dehydro‐β‐ionone (<jats:bold>46</jats:bold>) gave merely the isomeric open‐chain triene‐ketone <jats:bold>47</jats:bold>.</jats:p><jats:p>The structures assigned to the ethers <jats:bold>2</jats:bold>, <jats:bold>3</jats:bold>, <jats:bold>33</jats:bold>, <jats:bold>38</jats:bold> and to the alcohols <jats:bold>5</jats:bold>, <jats:bold>10</jats:bold>, <jats:bold>13</jats:bold> could be confirmed by chemical reactions and mutual interconversions. The structure of the ether <jats:bold>21</jats:bold> had to be established by X‐ray analysis, details of which are described.</jats:p><jats:p>A novel intramolecular hydrogen transfer is involved in formation of ethers <jats:bold>B</jats:bold>. The photocyclization <jats:bold>A → D</jats:bold> probably proceeds by addition of the carbonyl‐C atom to the double bond (<jats:bold>A → h</jats:bold>), followed by methyl (1 → 2)‐shift (<jats:bold>h → i</jats:bold>). Process <jats:bold>A → h</jats:bold> may also be involved in formation of compounds of type <jats:bold>C</jats:bold> and <jats:bold>E</jats:bold>.</jats:p>