Table 2.

Electrophile-mediated cyclization of N-propargylthioureas 55.

Entry	R	Reaction conditions	E+	56 Yield (%)	57 Yield (%)
1	H	I2 (2 equiv), DCM, 0 °C	I+	–	20
2	Ph	I2 (2 equiv), DCM, 0 °C	I+	18	25
3	4-OMe-Ph	I2 (2 equiv), DCM, 0 °C	I+	59	traces
4	Ph	NBS (1.1 equiv), DCM, rt	Br+	–	67
5	4-OMe-Ph	NBS (1.1 equiv), DCM, rt	Br+	–	68
6	4-Cl-Ph	NBS (1.1 equiv), DCM, rt	Br+	–	44
7	H	PhSeCl (1 equiv), DCM, 0 °C	PhSe+	–	45
8	Ph	PhSeCl (1 equiv), DCM, 0 °C	PhSe+	56	traces
9	4-OMe-Ph	PhSeCl (1 equiv), DCM, 0 °C	PhSe+	73	–
10	4-Cl-Ph	PhSeCl (1 equiv), DCM, 0 °C	PhSe+	51	–
11	H	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		–	–
12	Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		81	–
13	Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		60	–
14	Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		57	–
15	4-OMe-Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		76	–
16	4-OMe-Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		59	–
17	4-OMe-Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		58	–
18	4-Cl-Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		57	–
19	4-Cl-Ph	ArCH(OR1)2 (1.5 equiv), TMSOTf (1 equiv), DCM, −10 °C		65	–