| abstract |
The present invention relates to a method for preparing structural analogues of tetracyclic, pentacyclic, and polycyclic ergoline alkaloids, in four steps, from an indole-3-carboxaldehyde, wherein the method includes the following two key steps: a step of coupling an N-protected 4-iodized 3-fluorinated indolic analogue with an unsaturated dipolarophilic function promoter, in particular an organostannic compound, thus leading to 3-formyl-4-alkenylindole or 3-formyl-4-alkynylindole. Said intermediates comprise an aldehyde function, which is converted into azomethine ylide, as well as a dipolarophilic unsaturated function that enables the dipolar reaction [3+2] of the second key step. The cyclization reaction, i.e. cycloaddition, is performed with an α-amino-functionalized compound, for example an α-aminoester compound, and, after condensation and cycloaddition, results in anticipated tetracyclic, pentacyclic, and polycyclic indoles. |