Kshetra M. Biswas, R. Dhara, Sumita Roy
1984
Citations
0
Influential Citations
8
Citations
Journal
Tetrahedron
Abstract
Abstract Reduction of the indole-1-carboxaldehydes ( 1a - 1f ) with borane /THF gives the 1-methylindoles ( 4 ) in 42-91-% yields together with the di(indolylmethyl)ethers ( 8 ), the indolyl-methyl indolines ( 7 ), the unsymmetric ether( 10 ) and the indolenine ( 11 ) as the minor products, except 7a . This appears to be the first report on the formation of symmetric ethers in the borane/THF reduction of an oxygen function. The formation of 7a and 7b from 1a and 1b implies that electrophilic substitution takes place primarily at position 3 of 3-substituted indoles, 1c - 1f did not form the corresponding 7 probably because of steric hindrance. These results are discussed in relation to the mechanisms of borane/THF reduction, origin of the different products and electrophilic substitution in 3-substituted indoles.