Selective demethylation of 2,5-dimethoxybenzaldehyde to 5-hydroxy-2-methoxybenzaldehyde

Abstract

dified with concentrated HC1 to precipitate 1.1 g (5%) of 3b, mp 133-135°( reported3 mp 134°).B. From Base Rearrangement of lb. A mixture of 1.0 g (0.005 mol) of lb and 100 ml of 1 TV NaOH was warmed on the steam bath for 5 min or until complete solution took place. The cooled solution was acidified with concentrated HC1 to precipitate 3b: 0.80 g (86%); mp 133-135°; ir (Nujol) 1730 (acetyl C=0), 1615 cm-1 (2-pyrone C=0); uv max (95% EtOH) 212 nm (e 23,000), 300 (14,000), 320 sh (9600); mass spectrum m/e (rel intensity) 204 (60), 189 (40), 162 (20), 121 (60), 120 (60), 105 (10), 93 (15), 92 (50), 77 (25), 43 (100).4-Hydroxy-3-(l-oxopropyl)-2H-l-benzopyran-2-one (3c). A mixture of 5.5 g (0.028 mol) of methyl salicyloylacetate, 150 ml of xylene, 19.5 g (0.15 mol) of propionic anhydride, and 30 g of powdered potassium carbonate was heated with stirring at 135°for 0.5 hr. Ether (300 ml) was added to the cooled mixture and the solids were filtered and washed with ether. The filter cake was stirred with 500 njl of water, the insoluble portion was filtered, and the filtrate was acidified with concentrated HC1 to precipiate 4.8 g (78%) of 3c: mp 122-124°(reported8 mp 123°); ir (Nujol) 1720 (acyl C=0), 1610 cm"1 (2-pyrone C=0); uv max (95% EtOH) 226 nm sh (e 15,200), 301 (13,300); mass spectrum m/e (rel intensity) 218 (50), 200 (15), 189 (100), 162 (17), 121 (50), 120 (25), 105 (12), 93 (12), 92 (25), 77 (25), 43 (5).

The Selective Reaction of Aryl Halides with KOH: Synthesis of Phenols, Aromatic Ethers, and Benzofurans

“…Mp = 110-115 o C (lit. [11] 114-116 o C). 1 H NMR (400 MHz, d 6 -acetone) δ: 10.38 (s, 1H), 7.19 (d, J = 3.2 Hz, 1H), 7.06-7.14 (m, 2H), 3.90 (s, 3H).…”

“…3-Hydroxy-6-methoxybenzaldehyde (Table 1, Entry 10). [11] Using the general procedure, 3-bromo-o-anisaldehyde (106 mg, 0.500 mmol), Pd 2 dba 3 (9.2 mg, 0.010 mmol), L2 (20 mg, 0.04 mmol), KOH (60 mg, 1.0 mmol) in 1,4-dioxane (0.5 mL) and degassed water (0.3 mL) were allowed to react at 80 o C for 18 h. The crude material was purified by column chromatography (eluting with 2:1 hexanes:ethyl acetate) to give the title compound as a yellow solid (67 mg, 88%).…”

1-[2-Methoxy-5-(3-phenylpropyl)]-2-aminopropane Unexpectedly Shows 5-HT2A Serotonin Receptor Affinity and Antagonist Character

“…4-Bromo-5-hydroxy-2-methoxybenzaldehyde(15): Method I. According to a procedure described by Ulrich et al, 9 concentrated H2SO4 (20 mL) was slowly added to 4-bromo-2,5-dimethoxybenzaldehyde 19 (2.5 g, 10.20 mmol) with ice cooling, and the mixture was heated at 50-55°C for 48 h. The reaction mixture was poured into ice, and precipitated oil was extracted with Et2O (4 × 25 mL). The Et2O solution was extracted with 5% NaOH solution (75 mL), and the aqueous portion was acidified with dilute HCl and then extracted with Et2O (4 × 30 mL).…”

Total Synthesis and Structural Revision of Clavilactone D

“…However, compound 18 underwent a regioselective bromination. Thus, selective demethylation of dimethyl ether 17 with concentrated sulfuric acid provided monomethyl ether 18 . Treatment of 18 with pyridinium tribromide produced desired brominated product 19 , which was re‐methylated to 14 .…”