Abstract A new, efficient synthesis of thiopyrylium tetrafluoroborate (C 5 H 5 S+ BF 4−) is described. It is based on the three-step sequence ethyl vinyl sulfide [RIGHTWARDS ARROW] propargyl vinyl sulfide [RIGHTWARDS ARROW] 2H-thiopyran [RIGHTWARDS ARROW] C 5 H 5 S+ BF 4− in an overall yield of 54%. Preparations of C 5 H 5 S+ BPh 4−, C 5 H 5 S+ I−, and C 5 H 5 S+ CF 3 SO 3−(TfO−) are also described. The latter is the subject ...
