2-(2-Oxo-1-phthalimidoethylidenyl)-1,3-dithiolane. An Unexpected Product from an Attempted Cleavage of a Dithiolane with Ceric Ammonium Nitrate

Abstract

Currently, there is considerable interest in the synthesis of peptide derivatives bearing an aldehyde at the C-terminal position in place of the carboxyl group^1,2. This interest may have arisen from, and been intensified by, the identification of several peptide aldehydes as products of microbiological fermentation broths³. Synthetic routes to this type of compound require considerable development. Conventional peptide synthetic procedures are not directly applicable to an unprotected amino aldehyde residue due to the reactivity of the latter. The general synthetic strategy will probably require the generation or unmasking of the aldehyde group as the last step in the preparation of such “peptidals”. Thus far the few syntheses published in this area have relied either on the hydrolysis of an aldehyde derivative such as a semicarbazone ^{3a, 4}, or on the Pfitzner-Moffatt oxidation of a terminal primary alcohol group².