Electrocyclic Reactions of Siloles: A Combined Experimental and Theoretical Study. Issue 16 (11th March 2014)

• Record Type: Journal Article
• Authors: Meyer‐Wegner, Frank; Wender, Josef H.; Falahati, Konstantin; Porsch, Timo; Sinke, Tanja; Bolte, Michael; Wagner, Matthias; Holthausen, Max C.; Lerner, Hans‐Wolfram
• Is Part Of: Chemistry. Volume 20:Issue 16(2014)
• Page Start: 4681
• Page End: 4690
• Publication Date: 2014-03-11
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201302544
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The reaction of 4‐chloro‐1, 2‐dimethyl‐4‐supersilylsila‐1‐cyclopentene (<bold>2 a</bold>) with Li[N<italic>i</italic>Pr<sub>2</sub>] at −78 °C results in the formation of the formal 1, 4‐addition product of the silacyclopentadiene derivative 3, 4‐dimethyl‐1‐supersilylsila‐1, 3‐cyclopentadiene (<bold>4 a</bold>) with 2, 3‐dimethyl‐4‐supersilylsila‐1, 3‐cyclopentadiene (<bold>5 a</bold>). In addition the respective adducts of the Diels–Alder reactions of <bold>4 a</bold>+<bold>4 a</bold> and <bold>4 a</bold>+<bold>5 a</bold> were obtained. Compound <bold>4 a</bold>, which displays an s‐<italic>cis</italic>‐silacyclopentadiene configuration, reacts with cyclohexene to form the racemate of the [4+2] cycloadduct of <bold>4 a</bold> and cyclohexene (<bold>9</bold>). In the reaction between <bold>4 a</bold> and 2, 3‐dimethylbutadiene, however, <bold>4 a</bold> acted as silene as well as silacyclopentadiene to yield the [2+4] and [4+2] cycloadducts <bold>10</bold> and <bold>11</bold>, respectively. The constitutions of <bold>9</bold>, <bold>10</bold>, and <bold>11</bold> were confirmed by NMR spectroscopy and their crystal structures were determined. Reaction of 4‐chloro‐1, 2‐dimethyl‐4‐<italic>tert‐</italic>butyl‐4‐silacyclopent‐1‐ene (<bold>2 c</bold>) with KC<sub>8</sub> yielded the corresponding disilane (<bold>12</bold>), which was characterized by X‐ray crystal structure analysis (triclinic, <italic>P</italic><tex-math notation="tex"><![CDATA[$\bar 1$]]></tex-math><inline-graphic xlink:href="ark:/27927/pgg58fgx5gr" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" />). DFT calculations are used to unveil the mechanistic scenario underlying the observed reactivity.</p> </abstract>