Synthesis of 4-Arylpyridines and Substituted β-Carbolines via 1,4-Grignard-Addition to Pyridinecarboxamides.

Article abstract of DOI:10.1016/0040-4020(95)00596-Z

2,5-Pyridinedicarboxamides 1 and 2, 5-bromo-3-pyridinecarboxamide 7 and 3-hydroxy-2,5-pyridinedicarboxamide 9 undergo 1,4-addition with Grignard reagents to give the 2,4,5- or 3,4,5- and 2,3,4,5-substituted pyridines 3-6, 8 and 10 after oxidation with NCS or oxygen.After selective transformation of amides 5 and 8 to carbamates 17 and 19, a modified intramolecular Golberg amide arylation furnishes the β-carbolines 22 and 24 in good yields.