Electroytic partial fluorination of organic compounds. 52. Regio- and diastereoselective anodic fluorination of thiazolidines

Anodic fluorination of N-benzoyl, N-acethyl-, and N-formylthiazolidine deri ved from L-cysteine was carried out in dimethoxyethane (DME) and acetonitri le containing various supporting fluoride salts using an undivided cell. Hi ghly regioselective fluorination proceeded to provide the corresponding 5-m onofluorinated thiazolidine derivatives in good yields in DME, and the dias tereoselectivitiy was moderate to high regardless of the supporting fluorid e salts. The diastereoselectivitiy of the fluorination was greatly affected by the bulkyness of the subsitituent on the nitrogen atom, and N-benzoylth iazolidine gave much higher diastereoselectivity compared with N-formyl der ivative. The fluorination of the thiazolidines was not achieved by commerci ally available fluorinating reagents such as N-fluoropyridinium salts.