ISSN:
0009-2940
Keywords:
Silene, neopentyl-
;
Me3SiO substituents
;
Cycloaddition reactions
;
Silaethene derivatives
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Silaheterocycles, XXV[1]. - (Me3SiO)2Si—CHCH2tBu: A Siloxy-Functionalized Synthetic Equivalent for Dichloroneopentylsilene(Me3SiO)2Si—CHCH2tBu (4) is obtained by the reaction of (Me3SiO)2Si(Cl)CH=CH2 (2) with LitBu. The reaction proceeds via the α-lithiated species 3, which can be intercepted by trimethylsilyl triflate to give 5. Silaethene 4 dimerizes to the E/Z-isomers of disilacyclobutane 7 and adds to Me3SiOMe to give 6. The reactivity of 4 resembles that of Cl2Si—CHCH2tBu (1): A [4 + 2] cycloadduct is obtained from the reaction with anthracene, and with 1,3-cyclohexadiene and 1,3-cycloheptadiene mixtures of monosilacyclobutanes (10 and 12) and bicyclic Diels-Alder adducts (9 and 11) are available. Exclusive [2 + 2] cycloaddition reactions take place with styrene (formation of 13), 2,3-dimethyl-1,3-butadiene (→19), and 1,3-butadiene (→21). With quadricyclane only the product (14) originating from a [2 + 2 + 2] cycloaddition is formed, while with 2,5-norbornadiene the [2 + 2] and [2 + 2 + 2] cycloadducts (14 and 15) are formed. In addition the ene products (16, 18, 20, 22) are isolated in some cases from side reactions. - The tendency of 1 and 4 to preferably participate in [2 + 2] cycloaddition reactions is ascribed to the polarity of the Si—C bond and the additional influence of the π donor ligands at silicon. These factors enable a stepwise [2 + 2] reaction in which the primary zwitterionic intermediates B are cyclized to yield the SiC four-membered ring compounds.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931261004
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