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

Anodic fluorination of N-benzoyl, N-acethyl-, and N-formylthiazolidine derived from L-cysteine was carried out in dimethoxyethane (DME) and acetonitrile containing various supporting fluoride salts using an undivided cell. Highly regioselective fluorination proceeded to provide the corresponding 5-monofluorinated thiazolidine derivatives in good yields in DME, and the diastereoselectivitiy was moderate to high regardless of the supporting fluoride salts. The diastereoselectivitiy of the fluorination was greatly affected by the bulkyness of the subsitituent on the nitrogen atom, and N-benzoylthiazolidine gave much higher diastereoselectivity compared with N-formyl derivative. The fluorination of the thiazolidines was not achieved by commercially available fluorinating reagents such as N-fluoropyridinium salts.

Alkylation reaction of phosphorus oxyacids.

Alkylation reactions of phosphorus oxyacids (i.e. phosphoric acid, phosphorous acid, hypophosphorous acid) were examined by means of several methods for the synthesis of the corresponding esters. These reactions were applied to the synthesis of oligonucleotide having phosphotriester bond or phosphonate diester bond.