Boron tribromide → ethyl(E)-3-{2-[3-(1-adamantyl)-4-hydroxyphenyl]-5-pyrazinyl}-2-propenoate

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Reaction Steps

A solution of ethyl(E)-3-{2-[3-(1-adamantyl)-4-benzyloxyphenyl]-5-pyrazinyl}-2-propenoate (477 mg, 0.96 mmol), 1.0 M boron tribromide (3.86 mmol) in CH2Cl2 (3.86 mL), and CH2Cl2 (13 mL) was stirred at −78° C. under argon for 2 h, quenched with water (50 mL), and extracted with EtOAc (100 mL, 50 mL, and 30 mL). The extracts were washed (brine) and dried. After solvent removal at reduced pressure, the residue was purified on silica gel (20% to 33% EtOAc/hexane) to give 367 mg (94%) of ethyl(E)-3-{2-[3-(1-adamantyl)-4-hydroxyphenyl]-5-pyrazinyl}-2-propenoate as a yellow solid, mp 212-215° C. IR 3352, 2843, 1686 cm−1; 1H NMR (CDCl3) δ 1.35 (t, J=7.3 Hz, 3H, OCH2CH3), 1.79 (bs, 6H, AdCH2), 2.10 (bs, 3H, AdCH), 2.18 (bs, 6H, AdCH2), 4.29 (q, J=7.3 Hz, 2H, OCH2CH3), 5.32 (s, 1H, OH), 6.77 (d, J=8.5 Hz, 1H, 5-ArH), 6.97 (d, J=15.9 Hz, 1H, CH═CHCO), 7.71 (d, J=15.9 Hz, 1H, CH═CHCO), 7.75 (dd, J=8.5 Hz, 2.4 Hz, 1H, 6-ArH), 7.98 (d, J=2.4 Hz, 1H, 2-ArH), 8.62 (d, J=1.2 Hz, 1H, 3-PyrH), 8.97 ppm (d, J=1.2 Hz, 1H, 6-PyrH). HRMS calcd C25H28N2O3 [M+H]+ 405.2173. found 405.2181.

Provenance & Evidence