Reaction SMILES: Br[CH2:2][C:3]([NH:5][C@:6]12[CH2:41][CH2:40][C@@H:39]([C:42]([CH3:44])=[CH2:43])[C@@H:7]1[C@@H:8]1[C@@:21]([CH3:24])([CH2:22][CH2:23]2)[C@@:20]2([CH3:25])[C@@H:11]([C@:12]3([CH3:38])[C@@H:17]([CH2:18][CH2:19]2)[C:16]([CH3:27])([CH3:26])[C:15]([C:28]2[CH:37]=[CH:36][C:31]([C:32]([O:34][CH3:35])=[O:33])=[CH:30][CH:29]=2)=[CH:14][CH2:13]3)[CH2:10][CH2:9]1)=[O:4].C(N(CC)C(C)C)(C)C.Br.[C@H:55]12[CH2:61][C@H:58]([NH:59][CH2:60]1)[CH2:57][S:56]2(=[O:63])=[O:62]>C1COCC1.CO>[O:62]=[S:56]1(=[O:63])[CH2:57][C@@H:58]2[CH2:61][C@H:55]1[CH2:60][N:59]2[CH2:2][C:3]([NH:5][C@:6]12[CH2:41][CH2:40][C@@H:39]([C:42]([CH3:44])=[CH2:43])[C@@H:7]1[C@@H:8]1[C@@:21]([CH3:24])([CH2:22][CH2:23]2)[C@@:20]2([CH3:25])[C@@H:11]([C@:12]3([CH3:38])[C@@H:17]([CH2:18][CH2:19]2)[C:16]([CH3:27])([CH3:26])[C:15]([C:28]2[CH:37]=[CH:36][C:31]([C:32]([O:34][CH3:35])=[O:33])=[CH:30][CH:29]=2)=[CH:14][CH2:13]3)[CH2:10][CH2:9]1)=[O:4]
Reactant: C=C(C)[C@@H]1CC[C@]2(NC(=O)CBr)CC[C@]3(C)[C@H](CC[C@@H]4[C@@]5(C)CC=C(c6ccc(C(=O)OC)cc6)C(C)(C)[C@@H]5CC[C@]43C)[C@@H]12
Reactant: O=S1(=O)C[C@@H]2C[C@H]1CN2
Agent: Br
Solvent: C1CCOC1
Solvent: CCN(C(C)C)C(C)C
Solvent: CO
Product: C=C(C)[C@@H]1CC[C@]2(NC(=O)CN3C[C@@H]4C[C@H]3CS4(=O)=O)CC[C@]3(C)[C@H](CC[C@@H]4[C@@]5(C)CC=C(c6ccc(C(=O)OC)cc6)C(C)(C)[C@@H]5CC[C@]43C)[C@@H]12
Temperature: 155 °C
Reaction time: 5 h
Yield: 62.7 %

Procedure:
To a solution of methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(2-bromoacetamido)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)benzoate (95 mg, 0.143 mmol) in THF (2 mL) in a microwave reaction tube was added N,N-di-iso-propylethylamine (0.125 mL, 0.715 mmol) followed by (1S,4S)-2-thia-5-azabicyclo[2.2.1]heptane 2,2-dioxide, hydrobromide (98 mg, 0.429 mmol). The resulting slurry was heated to 155° C. in a microwave. After 5 h, the reaction mixture was diluted with MeOH (1 mL), filtered and purified by a reverse phase prep-HPLC using Prep HPLC method 1 to give methyl 4-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(2-((1S,4S)-2,2-dioxido-2-thia-5-azabicyclo[2.2.1]heptan-5-yl)acetamido)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)benzoate as a white solid (65.5 mg, 61% yield) after drying in a vacuum oven overnight at 50° C. LC/MS: m/e 731.3 (M+H)+, 2.88 min (method 1). 1H NMR (400 MHz, CHLOROFORM-d) δ 7.92 (d, J=8.3 Hz, 2H), 7.19 (d, J=8.3 Hz, 2H), 6.93 (s, 1H), 5.29 (d, J=4.9 Hz, 1H), 4.80 (s, 1H), 4.65 (s, 1H), 3.90 (s, 3H), 3.81 (br. s., 1H), 3.64 (br. s., 1H), 3.59 (d, J=11.2 Hz, 1H), 3.45 (d, J=16.1 Hz, 1H), 3.29 (d, J=12.7 Hz, 1H), 3.23 (d, J=16.1 Hz, 1H), 3.07 (dd, J=12.5, 2.9 Hz, 2H), 2.72-2.58 (m, 2H), 2.56-2.38 (m, 3H), 2.11 (dd, J=17.1, 6.4 Hz, 1H), 1.92-1.75 (m, 2H), 1.71 (s, 3H), 1.65 (d, J=5.6 Hz, 2H), 1.59-1.40 (m, 8H), 1.40-1.20 (m, 4H), 1.13 (d, J=13.0 Hz, 2H), 1.03 (s, 3H), 1.01 (s, 3H), 0.98 (s, 3H), 0.92 (s, 6H). 13C NMR (101 MHz, CHLOROFORM-d) δ168.0, 167.1, 148.9, 148.5, 146.2, 130.0, 128.4, 127.9, 123.9, 110.6, 64.4, 62.2, 61.0, 59.8, 59.4, 54.3, 52.6, 51.9, 49.2, 49.0, 48.0, 42.0, 41.6, 40.5, 38.5, 37.4, 36.2, 35.1, 34.5, 33.2, 29.6, 29.4, 28.7, 27.2, 25.0, 21.3, 21.0, 19.6, 19.1, 16.4, 15.7, 14.4