Design and syntheses of macrocyclic hosts containing convergent hydroxy groups

Metal‐Free Dehydration of Glucose to 5‐(Hydroxymethyl)furfural in Ionic Liquids with Boric Acid as a Promoter

“…Deuterium-labeling studies elucidated that the isomeriza-The ability to form stable complexes with fructose has further been utilized as a method of enriching fructose in the isomerization of glucose to fructose by the enzyme glucose isomerase. [24] Boric acid is also known to catalyze several reactions with important synthetic applications such as esterifications, [25] cyclization reactions [26] and decarboxylations. [27] So far no successful dehydrations of glucose to HMF with the aid of boric acid have been reported.…”

Axially Chiral Synthons for Dendrimer Synthesis

“…The monoester R,S-3 was alternatively prepared by deprotection of methyl phenacyl ester (see below). Analogously, methylation of known racemic [42][43][44] as well as chiral 45 2,2′-dihydroxy-1,1′-binaphthalene-3-carboxylic acid its methyl ester proceed under known 40 conditions giving R,S-, R-, and S-4 in 89, 94, and 83% yields, respectively. Hydrolyses of esters were performed using potassium hydroxide in methanol.…”

“…The method is a modification of known procedure 40 and diester 2 was isolated in 88% yield for R-2, and 93% yield for S-2. Racemic 2 was prepared from known dimethyl 2,2′-dihydroxy-1,1′-binaphthalene-3,3′-dicarboxylate 39 using methyl iodide and potasium carbonate in anhydrous acetone.…”

Selective Synthesis of [2+2] Macrocyclic Schiff Bases from Chiral 1,4‐Diamines

“…18 The high selectivity of the non-templated method for this type of macrocycles was deduced from the ESI-MS spectral analyses, wherein two primary ion peaks were assigned to the molecular ion peak and its half version, respectively. The preparation of macrocycles 2a-2c was realized in the presence of a boric ion as a template, which has been used by Pierre 8 and Hisaeda. 9 The ESI-MS data displayed that the [2＋2] cyclization products were selectively formed, which was considered to be attributable to the 'covalent template' effect described by Pierre.…”