The Regioselective 4-Benzylation of 2,4-Dihydroxybenzaldehyde

Assembled Dendritic Titanium Catalysts for Enantioselective Hetero‐Diels–Alder Reaction of Aldehydes with Danishefsky's Diene

“…[8] The reaction between 1-methoxy-3-(trimethylsilyloxyl)buta-1,3-diene (Danishefsky×s diene) 11 and aldehydes 12 provides a powerful access to 2-substituted 2,3-dihydro-4H-pyran-4-ones (13), a class of heterocycles with extensive synthetic applications in both natural and non-natural products. [9,10] Seebach and co-workers have reported that a cross-linked dendritic salen±Cr III catalyst promotes the HDA reaction of Danishefsky×s diene with aldehydes to give the corresponding adducts with less than 80 % ee and in 82 % conversion.…”

“…[13,14] A mixture of dendritic benzyl bromide (1.00 equiv), 2,4-dihydroxybenzaldehyde or 2,5-dihydroxybenzaldehyde (1.2 equiv), dried potassium carbonate (1.5 equiv), and potassium iodide (0.1 equiv) in dry acetonitrile was heated to reflux and stirred vigorously under argon atmosphere for 10 h. The mixture was allowed to cool and then concentrated to dryness under reduced pressure. The residue was partitioned between 1 n aqueous HCl and CH 2 Cl 2 , and the aqueous layer was extracted with CH 2 Cl 2 .…”

Application of a Newly Synthesized Calixarene in Metal Ions Extraction

“…As the yield was very low, KI was added to the reaction mixture to increase the rate of the reaction. This approach was attempted based on a study by Mendelson et al [34], who noted that iodide ion was necessary to accelerate the reaction. Unfortunately, addition of KI only increased the product to 2%.…”

Catechol–bisphosphonate conjugates: New types of chelators for metal intoxication therapy

“…The polybenzyloxy phenylalkenylaldehydes 1 [4] were condensed with tetraethyl bisphosphonates catalyzed by titanium tetrachloride and N-methylmorpoline at room temperature [5]. The obtained alkenylidene bisphosphonates 3 were then hydrogenated with Pd/C to give polybenzyloxy phenylalkyl bisphosphonates 4.…”