ISSN:
0947-6539
Keywords:
allylsilanes
;
catalysis
;
cyclizations
;
oxidations
;
palladium
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Palladium-catalyzed oxidation of cyclic 1,3-dienes 3, 5, 9, 11, and 13, with an allylsilane group in the side chain, led to an intramolecular 1,4-syn-addition to the conjugated diene through a carbocyclization. Acyclic trienesilanes 7 also underwent analogous 1,4-oxidations. The reaction was carried out in acetone-acetic acid (2:1) with a slight excess of LiCl. p-Benzoquinone was employed as the oxidant and Li2PdCl4 as the catalyst. The reaction proceeds through an intramolecular trans addition of the allylsilane to a (π-diene)palladium complex to produce a bicyclic (π-allyl)palladium intermediate. Subsequent trans attack by chloride at the π-allyl intermediate gives the product. The intermediate (π-allyl)palladium complex was isolated and fully characterized. It was unambiguously demonstrated that the allylsilane had attacked the coordinated double bond trans to palladium (trans-carbopalladation). The use of CuCl2 as the oxidant, instead of p-benzoquinone, gave a less stereoselective addition, but interestingly, with the opposite stereochemistry.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19970030320
Permalink
