Compound 16

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InChIKey DBHRKAFVWRKTKR-BNHYGAARSA-N

Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.

A solution of 580 mg (2.87 mmol, 1 eq.) chloro pyrrolizidine 15 and 990 mg (7.18 mmol, 2.5 eq.) K₂CO₃ in MeOH (30 mL) was stirred in a microwave reactor for 10 min at 150 °C/300 W. 10 g silica was added and the reaction mixture was concentrated in vacuo. The crude product was purified by flash column chromatography (CHCl₃:MeOH = 10:1) to yield 429 mg (2.58 mmol, 90%) azide 16 as a yellow oil (one spot on TLC). TLC (CHCl₃:MeOH:NH₄OH = 9:1:0.2), R_f = 0.67 (KMnO₄). ¹H NMR (CDCl₃, 400 MHz): δ= 4.47 (dd, J=1.8, 4.5 Hz, 1H), 4.15 (s, 1H), 4.06 (s, 1H), 3.49 (d, J=11.7 Hz, 1H), 3.31 (s, 1H), 3.14–3.10 (m, 1H), 3.02–2.97 (m, 1H), 2.45 (d, J=11.7 Hz, 1H), 2.10–2.05 (m, 1H), 2.02–1.96 (m, 1H). ¹³C NMR (CDCl₃, 100 MHz): δ= 82.1, 74.4, 69.6, 66.4, 61.2, 54.8, 33.7. IR (Diamond-ATR, neat) ν_max: 2940, 2103, 1354, 1310, 1263, 1097, 1050, 1006, 958, 849, 791, 724 cm^-1. [α]²⁵ _D – 49.2° (c= 0.44, CHCl₃). HRMS (ESI) calcd for C₇H₁₀N₄O [M+H]⁺: 167.0927; found: 167.0928.