KBS1: Bridging of cyclam
Prepared according to a previously described method. Cyclam (1.05 g, 5.2 mmol) was dissolved in water (80 mL) and formaldehyde (37%, 0.8 mL, 10.6 mmol, 2 equiv.) was added. The mixture was stirred at 0 °C for one hour before being filtered in vacuo and washed with ice cold water (3 x 20 mL) to yield bridged cyclam as a white powder (0.877 g, 78%).
m.p. 104 – 107 °C (lit. 106 – 108 °C).
LRMS (ESI+) m/z 225.2 [M + H]+.
1H NMR (300 MHz, CDCl3) δ 5.43 (dt, J = 10.9, 2.3 Hz, 2H), 3.22 – 3.08 (m, 4H), 2.89 (d, J = 10.9 Hz, 2H), 2.87 – 2.79 (m, 3H), 2.68 – 2.55 (m, 4H), 2.41 – 2.34 (m, 6H), 1.18 (dtt, J = 13.5, 3.6, 1.6 Hz, 2H).
Spectroscopic values were in agreement with those reported in the literature.
Earlier attempts are not on GitHub.
KBS1-2 - 62%