Radikalinduzierte intramolekulare 1, 4‐Verschiebung einer Formylgruppe

Radical-induced Intramolecular 1,4-Transfer of a Formyl Group A further example of a radical-induced intramolecular shift of a functional group in steroids is described. In analogy to the sequence leading to the 1, 4-transfer of cyano groups [3], 11 β-nitrite photolysis was used to generate the appropriate C (18) radical in the 20-hydroxy-11 β-nitrosyloxy-pregnene-21-al 6. Intramolecular addition of the radical center to the double-bond of the specially adjacent aldehyde function, followed by fragmentation of the intermediate cyclic alkoxy radical and subsequent oxidation lead directly to the rearranged 18-formyl compound 10.