摘要:
Indoles are converted into alpha-carbolines in four steps by acylation at C-3, Boc-protection, olefination of the resulting 3-indolylaldehydes or ketones to give N-Boc-3-indolyl alkenyl oxime O-methyl ethers, which upon heating to 240 degrees C under microwave irradiation undergo loss of the Boc-group, and 6 pi-electrocyclization to alpha-carbolines, following aromatization by loss of methanol (11 examples, 30-90% yield).