ISSN:
0009-2940
Keywords:
Carbenoids
;
Halogen-metal exchange
;
Stereoisomerisation
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The diastereomeric carbenoids 6 are generated at -125°C from the dibromocyclopropane 5 by halogen-metal exchange and trapped by electrophiles. Since the resulting carbenoids 6 equilibrated by halogen-metal exchange with their precursor dibromo compound 5, the product ratios depend strongly on the reaction conditions used. Normal addition of n-butyllithium favors equilibration giving “thermodynamic ratios” of the carbenoids. Inverse addition of 5 to tert-butyllithium approaches the “kinetic ratio” of carbenoids, which is revealed in reactions in which the carbenoids are trapped in situ by alcohols. The carbenoids 6 have been found to be configurationally stable at -125°C. They undergo rapid equilibration at temperatures above -78°C before decomposition sets in at -60°C.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240544
