Synthesis of 1-Chloroalkynes from Alkynylsilanes Using Trichloroisocyanuric Acid as Chlorinating Agent

Vilhelmsen MieHøjer. Andersson AsbjørnSune. Nielsen MogensBrøndsted. Synthesis  2009,  1469 

When revisiting the reaction conditions and the product composition of the previously reported chlorination reaction, we found that the reaction products are, in the case of unsubstituted and donor-substituted arylalkynes (R = H, OMe, t-Bu), not exclusively the reported chloroalkynes but to a large extent also chlorinated ketones.

Corrected products and yields under various conditions for the chlorination of p-RC₆H₄C≡CSiMe₃ using trichloro­isocyanuric acid (TCCA) and silver nitrate are provided here. These should replace Scheme  [²] and Table  [¹] in the original paper. We apologize for the mistake and for any inconvenience it may have caused.

Scheme 2

Table 1 Corrected Products and Yields Obtained from Chlorination of p-RC₆H₄CºCSiMe₃

R (starting material)	Scalea	TCCAb	AgNO3 c	Conditionsd	Product yields (%)
CN (1)	1.53	1.03	0.10	0 ˚C for 5 h	2 (93)
CN (1)	1.59	1.03	0.19	H2O (19 equiv); 0 ˚C for 30 min, then 40 ˚C for 24 h	2 (84)
CN (1)	1.54	1.07	0.20	H2O (20 equiv); 0 ˚C for 30 min, then µw for 5 min	2 (98)
H (3a)	1.82	1.00	0.10	0 ˚C for 5 h, then r.t. for 19 h	3b (23)
H (3a)	1.02	1.08	0.21	0 ˚C for 30 min, then reflux for 20 h	3 (7); 3b (34); 3c (8)
H (3a)	1.02	1.09	0.20	0 ˚C for 30 min, then µw for 5 min	3 (<20); 3b (8); 3c (10)
OMe (4)	1.54	1.00	-	Bu4NF (1 M soln in THF; 0.68 equiv); 0 ˚C for 70 min, then r.t. for 30 min	5 (11); 6 (25)
OMe (4)	1.59	1.07	0.09	0 ˚C for 30 min, then 40-50 ˚C for 72 h	6 (31); 4c (27); 4d (21)
OMe (4)	1.03	1.07	0.20	0 ˚C for 30 min, then reflux for 20 h	6 (29); 4c (37)
OMe (4)	1.03	1.08	0.19	0 ˚C for 30 min, then µw for 5 min	6 (26); 4c (24)
NO2 (8a)	1.38	1.10	0.21	H2O (20 equiv); 0 ˚C for 30 min, then 40 ˚C for 24 h	8 (50)
NO2 (8a)	1.40	1.12	0.21	H2O (20 equiv); 0 ˚C for 5 min, then µw for 5 min	8 (42)
NO2 (8a)	1.00	1.12	0.20	0 ˚C for 30 min, then reflux for 20 h	8 (76)
NO2 (8a)	1.00	1.10	0.20	0 ˚C for 30 min, then µw for 5 min	8 (>99)
t-Bu (9a)	1.08	1.13	0.23	H2O (20 equiv); 0 ˚C for 30 min, then 40 ˚C for 30 min	9 (43); 9b (57)
t-Bu (9a)	0.84	1.11	0.20	H2O (20 equiv); 0 ˚C for 5 min, then µw for 5 min	9 (26); 9b (58)
t-Bu (9a)	0.97	1.13	0.21	0 ˚C for 30 min, then reflux for 20 h	9b (34); 9c (23)
t-Bu (9a)	1.02	1.08	0.20	0 ˚C for 30 min, then µw for 5 min	9b (19); 9c (<13)
a Amount of p-RC6H4CºCSiMe3 in mmol. b Molar equivalents of TCCA relative to p-RC6H4CºCSiMe3. c Molar equivalents of AgNO3 relative to p-RC6H4CºCSiMe3. d µw = microwave heating at 150 ˚C.