An improved and scale-up synthesis of 6-hydroxybenzofuran

Studies toward the Total Synthesis of Parvifolals A/B: An Intramolecular o-Quinone Methide [4 + 2]-Cycloaddition To Construct the Central Tetracyclic Core

“…Thus, our initial aim was set to synthesize the advanced intermediate 3 . In this direction, the starting benzofuran 4 (7) and the coupling partner 5 (8) have been synthesized according to known literature procedures. The cross-coupling of 4 and 5 has been executed according to Docuhet’s protocol for direct C2–H arylation.…”

“…Thus, our initial aim was set to synthesize the advanced intermediate 3 . In this direction, the starting benzofuran 4 and the coupling partner 5 have been synthesized according to known literature procedures. The cross-coupling of 4 and 5 has been executed according to Docuhet’s protocol for direct C2–H arylation. , Under the established conditions that consists of using Pd­(OAc) 2 (5 mol %) and KOAc (2 equiv) in dry N , N -dimethylacetamide (DMA) at 130 °C for 24 h, the cross-coupling reaction of 4 and 5 gave the required product 6 in 31% yield, where 58% of 4 was recovered (Scheme ).…”

“…A suspension of benzofuran 4 (7) (1.00 g, 6.75 mmol), bromoaldehyde 5 (8) (1.98 g, 8.10 mmol), Pd(OAc) 2 (75 mg, 0.37 mmol), and KOAc (1.32 g, 13.50 mmol) in dry DMA (10 mL) was heated at 130 °C for 24 h in a sealed tube. The reaction mixture was cooled, treated with water, and extracted with EtOAc (3 × 50 mL).…”

Synthesis of N-Pyridin-2-ylmethyl and N-Quinolin-2-ylmethyl ­Substituted Ethane-1,2-diamines

“…Treatment of 4 with either aluminum trichloride (refluxing in 1,2-dichloroethane) or sodium dodecane-1-thiolate (up to 140 °C) did not give any desired product. 33 Finally, HBr (48%) was used for this reaction and the demethylated product 5 was successfully obtained in good yield. 34 Analogue 5 was esterified in methanol to give methyl ester 6 and subsequently reacted with BOC-aminoethylbromide to afford intermediate 7, which was then treated with excess ethylenediamine to form 8.…”

4-, 5-, 6-, and 7-Hydroxybenzofuran: a unified strategy for a two-step synthesis of versatile benzofuranic building blocks

“…The starting cyclic compound can be a diphenol, a methoxyphenol, 1,4-benzoquinone, hydroquinone or cyclohexanedione, in which a two-carbon unit must be inserted to obtain the oxygenated heterocycle, [16][17][18][19][20][21][22][23][24] or, alternatively, a hydroxy-or methoxy-substituted salicylaldehyde, which needs the insertion of only one carbon instead. [25][26][27][28] Almost all the syntheses require at least three steps. The overall yields are all lower than 55%, except that of 6-HBF from 4-methoxysalicylaldehyde (73%), which is claimed in a paper dedicated to the improvement of 6-HBF synthesis.…”