Tylosin Derivatives: V. Electrochemical Opening of Oxirane Ring

In the preceding paper we described the chemical deepoxidation of 1 with dissolving metal (Zn). Reductive oxirane cleavage was accompanied by simultaneous allylic rearrangement giving 10,13-dihydro-13-hydroxy desmycosin (5). It is noteworthy that preparation of 1 consists of two steps: oxidation of the 12,13-double bond with m-chloroperbenzoic acid with simultaneous formation of N-oxide, and reduction of the N-oxide with Ph sub(3)P. Until now, electrochemical reduction of conjugated epoxy ketones has been described only in the case of steroid compounds. In this paper we report electrochemical reduction of 1 at mercury electrode. The mechanism of reduction has been investigated by cyclic voltammetry and preparative scale electrolysis has been carried out for the isolation and identification of products.