Abstract
2-Alkylcyclopentanone phenylhydrazones (Ia, b) were refluxed with 98-100% formic acid to solely afford cis-1 : 2 : 3 : 3a : 4 : 8b-hexahydro-8b-alkyl-cyclopent (b) indoles (IVa, b) in the yields of 34% and 33%, respectively. Similar treatment of cyclopentanone phenylhydrazone with formic acid gave indoline (IVc) and indoles (IIc) and its N-formyl derivative (IIe). The reaction mechanism and stereochemistry of these products are discussed.
