ISSN:
0009-2940
Keywords:
Alkylation, reductive
;
Cycloannulation, regio- and stereoselective
;
Calculations, MMPMI
;
Valence isomerizations
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Reductive Transformations, 18[2]. - Cycloannulation and Bridging of Cyclooctatetraene[1]Reductive alkylations of cyclooctatetraene (1) with biselectrophiles have hitherto been described as proceeding solely under 1,2-cycloannulation. Using different alkylating agents with varying chain lengths, conformational mobility, and leaving groups we succeeded in achieving regio- and stereoselective reactions of the intermediate monoalkyl monoanion 3. By systematic variation of the biselectrophiles the subtle competition of 1,2- versus 1,4- and of 1,n-cis- versus 1,n-trans-cyclization is elucidated. It is shown that the regio- and stereoselectivity are controlled mainly by the structure of the alkylating reagents while other parameters such as solvent or leaving group do not play an important role. Reductive alkylation of 1 provides an easy access to a large number of compounds which may be oxidized to new cyclooctatetraene systems or serve as substrates for further skeletal rearrangements. - X- ray structure analyses are performed for compounds 15, 27 a, 28, and 29.
Additional Material:
12 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911241226
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