XYIII SIX reaction was complete within a minimum period. The reaction of XIX with L-or D- cysteine in warm 6 hydrochloric acid under nitrogen for 24 hours afforded the I,-and D-forms of 111 with equal but opposite rotation, indicating that no appreciable racemization had occurred during the condensation. This preparation of 111 was based on a similar reaction used to prepare the S-thyminylcysteine." That a much higher yield of L-I11 than D-I11 was ...