反应详情

Following the General Procedure of Description 8, MeTiCl3 was freshly prepared prior to use from commercial titanium tetrachloride (TiCl4) (4.73 mL, 8.17 g, 43.1 mmol) and methyl lithium (MeLi) (1.6 M in Et2O, 26.9 mL, 43.0 mmol) in anhydrous diethyl ether (Et2O) (230 mL). A solution of 2-methyl-4-nitro-benzaldehyde (7b) (7.11 g, 43.0 mmol) in anhydrous Et2O (200 mL) was added. Aqueous work-up afforded 7.0 g (90% yield) of the target compound (7c) as a yellow solid. The material was of sufficient purity to be used directly in the next step without further isolation and purification procedures. Rf: ˜0.24 (EtOAc/Hxn=1:2 v/v). 1H NMR (300 MHz, CDCl3): δ 8.07 (dd, J=8.7, 2.7 Hz, 1H), 7.99 (d, J=2.4 Hz, 1H), 7.72 (d, J=9.0 Hz, 1H), 5.18 (q, J=6.6 Hz, 1H), 2.42, (s, 3H), 1.92-1.88 (br. m, 1H), 1.47 (d, J=6.3 Hz, 3H) ppm.

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