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. 2018 Jun 5;14:1317–1348. doi: 10.3762/bjoc.14.113

Table 5.

Thermal cycloaddition of sydnones with internal non-symmetrical alkynes.

graphic file with name Beilstein_J_Org_Chem-14-1317-i058.jpg
entry R1 R2 R3 R4 conditions ratio
a:b		 yield [%]a ref.
1 Ph H Me Ph xylene, 135–140 °C, 20 h n.d. 83/– [1–2]
2 Ph H COOEt Ph toluene, 95 °C, 84 h n.d. 82–83/– [1–2]
3 4-Cl-Ph H COOEt Ph xylene, reflux, 3 h n.d. 92/– [2]
4 4-MeO-Ph H COOEt Ph xylene, reflux, 3 h n.d. 83/– [2]
5 4-Me-Ph H COOEt Ph xylene, reflux, 3 h n.d. 98/– [2]
6 Bn H COOEt Ph xylene, reflux, 16 h n.d. 46/– [2]
7 Ph Ph COOEt Ph p-cymene, 160 °C, 16 h n.d. 87/– [2]
8 Ph Me COOEt Ph xylene, 110 °C, 8 h 100:0 82 [1–2]
9 Ph H COMe Ph chlorobenzene, 130 °C, 12 h 100:0 100 [1–2]
10 Ph H COPh Ph xylene, 135–140 °C, 16 h 100:0 82 [1–2]
11 Me H COPh Ph o-DCB, reflux, 144 h 69:31 99 [16]
12 Ph H CN Cl chlorobenzene, 110 °C, 10 h n.d. 15/20 [66]
13 Ph H SO2Ph Me toluene, 100 °C, 24 h 100:0 58 [68]
14 Ph H SO2Ph Ph toluene, 100 °C, 24 h 100:0 73 [68]
15 Ph H COOMe CH(OMe)2 toluene, reflux, 60 h 21:79 84 [99]
16 Bn H COOMe CH(OMe)2 toluene, reflux, 72 h 19:81 80 [99]
17 Bn H COOMe CHO toluene, reflux, 18 h 72:28 90 [99]
18 Ph H COOMe CHO toluene, reflux, 18 h 66:34 93 [99]
19 Bn H COOMe CH2OH toluene, reflux, 72 h 50:50 75 [99]
20 Ph H COOMe CH2OH toluene, reflux, 48 h 60:40 79 [99]
21 Ph H CF3 4-MeO-Ph xylene, 120 °C, 48–72 h 93:7 56 [100]
22 Ph H CF3 4-NO2-Ph xylene, 120 °C, 48–72 h 93:7 93 [100]
23 Ph H CF3 4-MeS-Ph xylene, 120 °C, 48–72 h 93:7 90 [100]
24 Ph H CF3 2-Cl-Ph xylene, 120 °C, 48–72 h 94:6 92 [100]
25 Ph H CF3 4-MeSO2-Ph xylene, 120 °C, 48–72 h 92:8 86 [100]
26 Ph H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 93:7 75 [100]
27 4-Cl-Ph H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 93:7 90 [100]
28 4-MeO-Ph H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 93:7 84 [100]
29 Bn H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 91:9 65 [100]
30 t-Bu H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 93:7 58 [100]
31 Me H CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 92:8 92 [100]
32 Ph Me CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 84:16 75 [100]
33 Ph 4-Cl-Ph CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 60:40 57 [100]
34 Ph Br CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 71:29 73 [100]
35 Ph MeS CF3 4-Cl-Ph xylene, 120 °C, 48–72 h 43:57 62 [100]
36 t-Bu H COOEt Et xylene, reflux, 72 h n.d. 38/8 [101]
37 Ph H PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 74 [102]
38 Ph H 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 80 [102]
39 Ph H 4-Cl-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 72 [102]
40 4-MeO-Ph H PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 73 [102]
41 4-MeO-Ph H 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 74 [102]
42 4-MeO-Ph H 4-Cl-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 73 [102]
43 4-Me-Ph H PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 79 [102]
44 4-Me-Ph H 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3-4 h 100:0 83 [102]
45 4-Me-Ph H 4-Cl-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h 100:0 75 [102]
46 Me H COOEt CF3 xylene, 100 °C, 4 h n.d. 18/25 [103]
47 Ph H SnBu3 SiMe3 toluene, reflux 100:0 80 [78]
48 Ph H SiMe2Ph SiMe3 toluene, reflux n.d. 63/34 [78]
49 Ph H COMe SiMe3 toluene, reflux n.d. 81/16 [78]
50 Ph H BPin Ph xylene, reflux, 4 h 98:2 58 [79,81]
51 Ph H BPin Bu xylene, reflux, 4 h 71:29 64 [79,81]
52 Ph H BPin Me3Si xylene, reflux, 4 h 67:33 76 [79,81]
53 4-MeO-Ph H BPin Ph xylene, reflux, 4 h 98:2 58 [79]
54 4-NO2-Ph H BPin Ph xylene, reflux, 4 h 98:2 70 [79]
55 4-MeO-Ph H BPin Bu xylene, reflux, 4 h 83:17 55 [79]
56 4-NO2-Ph H BPin Bu xylene, reflux, 4 h 83:17 62 [79]
57 4-MeO-Ph H BPin Me3Si xylene, reflux, 4 h 67:33 61 [79]
58 4-NO2-Ph H BPin Me3Si xylene, reflux, 4 h 60:40 83 [79]
59 3-Py H BPin Ph xylene, reflux, 16 h >98:2 60 [84]
60 3-Py H BPin Me3Si xylene, reflux, 16 h 57:43 70 [81,84]
61 3-Py H BPin n-Bu mesitylene, reflux, 16 h 71:29 56 [84]
62 4-Me-Ph CHO PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 79/– [104]
63 4-Me-Ph CHO 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 74/– [104]
64 4-Me-Ph Br 4-MeO-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 62/– [104]
65 4-MeO-Ph Br 4-MeO-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 69/– [104]
66 4-Me-Ph Br PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 73/– [104]
67 4-Me-Ph Br 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 66/– [104]
68 4-MeO-Ph Br 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 63/– [104]
69 Ph Br 4-Me-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 72/– [104]
70 4-MeO-Ph MeCO PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 74/– [104]
71 4-MeO-Ph MeCO 4-MeO-PhCO 5-NO2-furan-2-yl xylene, reflux, 3–4 h n.d. 73/– [104]
72 Ph H 4-Me-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 71/– [105]
73 Ph H 4-MeO-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 73/– [105]
74 4-Me-Ph H PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 75/– [105]
75 4-Me-Ph H 4-Me-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 73/– [105]
76 Ph H 4-Cl-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 72/– [105]
77 4-Me-Ph H 4-Cl-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 77/– [105]
78 4-MeO-Ph H 4-Cl-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 78/– [105]
79 Ph H PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 80/– [105]
80 4-MeO-Ph H PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 75/– [105]
81 4-MeO-Ph H 4-Me-PhCO 5-NO2-thiophen-2-yl xylene, reflux, 3–4 h n.d. 76/– [105]
82 CH2CH2CH2 p-Tos Bu anisol, reflux, 0.5 h n.d. 90/– [106]
83 CH2CH2CH2 p-Tos Ph anisol, reflux, 0.5 h n.d. 89/– [106]
84 Ph 4-Me-Ph BPin Me3Si o-DCB, reflux, 48 h 100:0 48 [80]
85 Ph 4-NO2-Ph BPin Me3Si o-DCB, reflux, 48 h 100:0 70 [80]
86 Me H BPin Ph mesitylene, reflux, 48 h >98:2 53 [81]
87 Bn H BPin Ph xylene, reflux >98:2 62 [81]
88 Ph Ph BPin Ph o-DCB, reflux, 48 h >98:2 59 [81]
89 Ph Ph BPin Me3Si o-DCB, reflux, 48 h >98:2 73 [81]
90 Me Ph BPin Me3Si o-DCB, reflux, 48 h >98:2 68 [81]
91 Ph Me BPin Ph o-DCB, reflux, 48 h >98:2 53 [81]
92 Ph iPr BPin Ph o-DCB, reflux, 48 h >98:2 38 [81]
93 Ph Me BPin Me3Si o-DCB, reflux, 48 h >98:2 56 [81]
94 Ph iPr BPin Me3Si o-DCB, reflux, 48 h >98:2 43 [81]
95 4-NO2-Ph Me BPin Ph o-DCB, reflux, 18 h >98:2 67 [81]
96 4-NO2-Ph iPr BPin Ph o-DCB, reflux, 24 h >98:2 45 [81]
97 4-NO2-Ph Me BPin Me3Si o-DCB, reflux, 18 h >98:2 80 [81]
98 4-NO2-Ph iPr BPin Me3Si o-DCB, reflux, 24 h >98:2 69 [81]
99 CH2CH2CH2 BPin Me3Si xylene, reflux, 24 h
o-DCB, 180 °C, 24 h		 >98:2
100:0		 21
66		 [81]
[107]
100 CH2CH2CH2CH2 BPin Me3Si xylene, reflux, 24 h >98:2 79 [81]
101 CH2CH2CH2CH2 BPin Ph xylene, reflux, 24 h >98:2 70 [81]
102 CH2CH2CH2 BPin Ph o-DCB, 180 °C, 72 h 50:50 51 [107]
103 CH2CH2CH2CH2 graphic file with name Beilstein_J_Org_Chem-14-1317-i059.jpg 4-F-Ph mesitylene, 165 °C, 18 h n.d. 46/– [108]
104 CH2CH2CH2CH2 graphic file with name Beilstein_J_Org_Chem-14-1317-i060.jpg 4-F-Ph mesitylene, 165 °C, 18 h n.d. 66/– [108]
105 graphic file with name Beilstein_J_Org_Chem-14-1317-i061.jpg graphic file with name Beilstein_J_Org_Chem-14-1317-i062.jpg 4-F-Ph mesitylene, 140 °C, 4 h n.d. 30/– [108]
106 graphic file with name Beilstein_J_Org_Chem-14-1317-i063.jpg graphic file with name Beilstein_J_Org_Chem-14-1317-i064.jpg 4-F-Ph mesitylene, 140 °C, 4 h n.d. 45/– [108]
107 graphic file with name Beilstein_J_Org_Chem-14-1317-i065.jpg graphic file with name Beilstein_J_Org_Chem-14-1317-i066.jpg 4-F-Ph mesitylene, 160 °C, 24 h n.d. 12/– [108]
108 CH2SCH2 graphic file with name Beilstein_J_Org_Chem-14-1317-i067.jpg 4-F-Ph mesitylene, 160 °C, 48 h n.d. 13/– [108]
109 4-Cl-Ph H Me graphic file with name Beilstein_J_Org_Chem-14-1317-i068.jpg mesitylene, 140 °C, 18 h n.d. 13/– [109]
110 Ph H graphic file with name Beilstein_J_Org_Chem-14-1317-i069.jpg Me3Si o-DCB, μ-wave, 200 °C, 2 h n.d. 55/9 [84]
111 Ph I COOEt Br toluene, reflux, 18 h 76:24 52/16 [110]
112 Me I COOEt Br xylene, reflux, overnight 58:42 50/37 [110]
113 Bn I COOEt Br xylene, reflux, overnight 59:41 39/27 [110]
114 4-F-Ph I COOEt Br xylene, reflux, overnight 75:25 48/16 [110]
115 4-MeO-Ph I COOEt Br xylene, reflux, overnight 75:25 63/21 [110]
116 4-MeO-Ph I COOt-Bu Br xylene, reflux, overnight 77:23 43/13 [110]
117 4-MeO-Ph I COOEt I xylene, reflux, overnight 60:40 58/28 [110]
118 4-MeO-Ph Br COOEt I xylene, reflux, overnight – 0/0 [110]
119 CH2CH2CH2CH2 4-Py 4-F-Ph mesitylene, 165 °C, 16 h n.d. 27/– [85]
120 Ph H COOEt Br toluene, reflux, 18 h 46:54 41/48 [111]
121 4-Me-Ph H COOEt Br toluene, reflux, 18 h 44:56 41/49 [111]
122 4-MeO-Ph H COOEt Br toluene, reflux, 18 h 41:59 33/49 [111]
123 4-F-Ph H COOEt Br toluene, reflux, 18 h 47:53 38/43 [111]
124 Ph CF3 COOMe Me o-DCB, 180 °C, 24 h 85:15 90 [32]
125 Ph CF3 Ph n-Bu o-DCB, 180 °C, 24 h 52:48 62 [32]
126 Ph CF3 BPin Me3Si o-DCB, 140 °C, 48 h 90:10 68 [32]
127 Ph CF3 BPin n-Bu o-DCB, 140 °C, 72 h >98:2 55 [32]
128 Me 3,4,5-
triMeO-Ph		 BPin Me3Si xylene, 180 °C, 24 h 83:17 92 [89]
129 Bn 3,4,5-
triMeO-Ph		 BPin Me3Si xylene, 180 °C, 24 h 90:10 66 [89]
130 Me 3-BnO-
4-MeO-Ph		 BPin Me3Si xylene, 180 °C, 24 h 80:20 73 [89]
131 Bn 3-BnO-
4-MeO-Ph		 BPin Me3Si xylene, 180 °C, 24 h 90:10 64 [89]
132 Ph 4-Me-Ph BPin Me3Si xylene, 180 °C, 48 h >98:2 74 [91]
133 Ph 2-Py BPin Me3Si xylene, 180 °C, 48 h >98:2 52 [91]
134 Ph 2-thienyl BPin Me3Si xylene, 180 °C, 48 h 88:12 64/6 [91]
135 Me 4-Me-Ph BPin Me3Si xylene, 180 °C, 48 h >98:2 55 [91]
136 4-EtO-Ph 4-MeO-Ph BPin Me3Si xylene, 180 °C, 48 h 88:12 74 [91]

aIsolated overall yield or isolated yields of both regioisomers a/b. n.d. – not determined.