(ArOCH3 of A and B), 58.0 (C-5 of B), 58.5 (C-5 of A), 61.6
(CO2CH2CH3 of A), 61.8 (CO2CH2CH3 of B), 113.7, 113.9, 118.3
and 118.4 (ArCH × 4), 124.7, 125.0, 128.0 and 128.3 (ArC ×
4), 131.6 and 132.3 (ArCH × 2), 159.2 (2 signals) (ArC × 2),
169.7, 169.9, 170.3 and 170.6 (C-2 and CO2CH2CH3 of A and B);
m/z (CI+) 372 and 370 ([M + H]+, 87 and 100%); HRMS: (CI+)
Found: [M + H]+ 370.0654, C16H20NO479Br requires 370.0654;
Anal. Calcd for C16H20NO4Br: C, 51.91; H, 5.44; N, 4.12. Found:
C, 52.10; H, 5.70; N, 3.88%.
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(1S,9R)-4-Methoxy-10-methyl-11-oxo-10-azatricyclo-[7.2.1.02,7]-
dodeca-2,4,6-triene-1-carboxylic acid ethyl ester 23. Bromide 22
(40 mg, 0.10 mmol), t-BuOK (20 mg, 0.18 mmol, freshly sublimed
at 180 ◦C and ca. 0.01 mmHg), Pd(dba)2 (6.9 mg, 0.012 mmol)
and dppp (7.4 mg, 0.018 mmol) were placed in a re-sealable
tube, dissolved in anhydrous toluene (0.5 mL, degassed by three
freeze–pump–thaw cycles) and heated at 130 ◦C for 15 h. The
reaction mixture was then cooled to r.t., diluted with saturated aq.
NH4Cl solution (2 mL) and extracted with EtOAc (3 × 2 mL). The
organic extracts were dried (Na2SO4) and concentrated in vacuo
to afford a pale brown oil which was then purified by preparative
TLC (EtOAc–hexanes 1 : 1) to afford tricycle 23 (5.8 mg, 17%) as
a colourless oil; [a]D20 +40.0 (c = 0.4, CHCl3); mmax/cm−1 (film) 1739
(s), 1695 (m), 1232 (m); dH (400 MHz, CDCl3) 1.36 (3H, t, J =
7.2, CO2CH2CH3), 2.27 (1H, d, J = 11.0, C1–CH2), 2.72 (1H,
dd, J = 11.0 and 5.5, C1–CH2), 2.83 (3H, s, NCH3), 2.94 (2H,
d, J = 2.5, C8–H), 3.78 (3H, s, ArOCH3), 3.92 (1H, dt, J = 5.5
and 2.5, C9–H), 4.32–4.42 (2H, m, CO2CH2CH3), 6.79 (1H, dd,
J = 8.5 and 2.5, C5–H), 7.01 (1H, d, J = 8.5, C6–H), 7.22 (1H,
d, J = 2.5, C3–H); dC (125 MHz, CDCl3) 14.4 (CO2CH2CH3),
27.9 (NCH3), 29.8 (C-8), 37.9 (C1–CH2), 54.6 (ArOCH3), 55.4
(C-9), 56.2 (C-1), 61.5 (CO2CH2CH3), 111.4 (C-3), 114.8 (C-5),
123.8 (C-7), 131.2 (C-6), 135.7 (C-2), 158.2 (C-4), 169.6 and
171.5 (C-11 and CO2CH2CH3); m/z (CI+) 290 ([M + H]+, 100%);
HRMS: (CI+) Found: [M + H]+ 290.1382, C16H20NO4 requires
290.1392.
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Acknowledgements
We acknowledge EPSRC and GSK for financial support of this
research programme, and Dow Pharma for providing the Rh
hydrogenation catalysts used in this study
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