SYNTHESIS OF MONOETHYL-O-CARBORANES, DIETHYL-O-CARBORANES, TRIETHYL-O-CARBORANES, AND TETRAETHYL-O-CARBORANES BY ELECTROPHILIC ALKYLATION OF O-CARBORANE WITH ETHYL-BROMIDE IN THE PRESENCE OF ALCL3 AND THEIR TRANSFORMATIONS
Li. Zakharkin et al., SYNTHESIS OF MONOETHYL-O-CARBORANES, DIETHYL-O-CARBORANES, TRIETHYL-O-CARBORANES, AND TETRAETHYL-O-CARBORANES BY ELECTROPHILIC ALKYLATION OF O-CARBORANE WITH ETHYL-BROMIDE IN THE PRESENCE OF ALCL3 AND THEIR TRANSFORMATIONS, Russian chemical bulletin, 45(11), 1996, pp. 2614-2622
Optimal conditions for the preparation of 9-ethyl-, 9,12-diethyl, 8,9,
12-triethyl-, and 8,9,10,12-tetraethyl-o-carboranes under the action o
f EtBr on o-carborane in the presence of AlCl3 were determined. The be
havior of these o-carborane derivatives towards electrophilic and nucl
eophilic reagents was studied. The presence of four ethyl groups in po
sitions 8, 9, 10, and 12 of the carborane polyhedron increases the ele
ctron density on the boron atoms in positions 4, 5, 7, and 11 to the p
oint where they are able to enter into reactions of electrophilic subs
titution, and in positions 3 and 6 to the point that they become resis
tant to the action of nucleophilic reagents. Reactions of 1,2-dilithiu
m-8,9,10,12-tetraethyl-o-carborane with various electrophilic reagents
were studied.