As req'd by a certain Bee...
Total synthesis of mimosamycin
H Fukumi, H Kurihara, H Mishima. Chem Pharm Bull 26(7) (1978) 2175-2180.
[...]
3-methoxy-4-methylbenzaldehyde - 4-methyl-3-nitrobenzaldehyde (110 g) was added at once to a solution of SnCl2.2H2O (450 g) in 35% HCl (600 mL). The reaction was highly exothermic. As soon as the inner temperature of the reaction mixture reached at 100°C, the mixture was cooled to 0-5°C with ice-cooling. The resulting precipitates (stannic complex of 3-amino-4-methylbenzaldehyde) were filtered off and used to the following diazotization reaction without purification. To the suspended mixture of the complex in 35% HCl (600 mL) was added dropwise at 4-5°C a solution of NaNO2 (46 g) in H2O (50 mL) for 50 min. The mixture was stirred at the same temperature for 2 h, and the resulting pale yellow precipitates were filtered off. A solid of the dizaonium salt was added in portions to refluxing water (1.71) over 30 min and after evolution of nitrogen gas ceased, the mixture was cooled and extracted with DCM. Concentration of DCM extracts gave a crude product, which was purified by DCM elution through a short silica gel layer and by recystallization from benzene. Yield of 3-hydroxy-4-methylbenzaldehyde [1] was 54.5 g (60%). To a solution of 3-hydroxy-4-methylbenzaldehyde (10.6 g) in 2 N NaOH (60 mL) was added dropwise at 40-45°C Me2SO4 (15.9 g) for 10 min. The mixture was stirred at the same temperature for 1 h, cooled to 20°C and extracted with ether (150 mL). Usual work-up and recrystallization from n-hexane gave colorless needles (8.6 g, 88.5%) of 3-methoxy-4-methylbenzaldehyde, which melted at 45-46°C (lit [2] bp 101-103°C/10^-4 mmHg).
[1] NV Sidgwick e.a. JCS 123 (1923) 2819
[2] K Tsuda e.a. Chem Pharm Bull 10 (1962) 856.