反应详情

Following the General Procedure of Description 8, MeTiCl3 was freshly prepared prior to use from commercial titanium tetrachloride (TiCl4) (10.0 mL, 17.3 g, 91.0 mmol) and methyl lithium (MeLi) (1.6 M in Et2O, 57.0 mL, 91.0 mmol) in anhydrous diethyl ether (Et2O) (400 mL). A solution of 2-methyl-4-nitro-benzaldehyde (5j) (12.4 g, 75.01 mmol) in anhydrous Et2O (200 mL) was added. Aqueous work-up afforded 13.7 g (99% yield) of the target compound (5k) 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: ˜0.47 (EtOAc/Hxn=1:2 v/v). 1H NMR (300 MHz, CDCl3): δ 8.41 (d, J=2.4 Hz, 1H), 8.00 (dd, J=8.4, 2.4 Hz, 1H), 7.27 (d, J=9.0 Hz, 1H), 5.16 (q, J=6.3 Hz, 1H), 2.43 (s, 3H), 1.96 (br. s, 1H), 1.50 (d, J=6.3 Hz, 3H) ppm. The analytical data correspond to the data of compound (5b) of Method A.

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